First Asian Record of the Genus Parvulobathynella (Malacostraca: Bathynellacea)

with Description of Two New Species from Southeastern India and Amendment of
the Generic Diagnosis
Author(s): Yenumula Ranga Reddy, Elia Bandari, and Venkateswara Rao Totakura
Source: Journal of Crustacean Biology, 31(3):485-508.
Published By: The Crustacean Society
DOI: http://dx.doi.org/10.1651/10-3435.1
URL: http://www.bioone.org/doi/full/10.1651/10-3435.1

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JOURNAL OF CRUSTACEAN BIOLOGY, 31(3): 485-508, 2011

FIRST ASIAN RECORD OF THE GENUS PARVULOBATHYNELLA (MALACOSTRACA:

BATHYNELLACEA) WITH DESCRIPTION OF TWO NEW SPECIES FROM SOUTHEASTERN INDIA
AND AMENDMENT OF THE GENERIC DIAGNOSIS

Yenumula Ranga Reddy, Elia Bandari, and Venkateswara Rao Totakura

(RRY, corresponding author, yrangareddy@yahoo.com; VRT, tvrav@yahoo.com) Department of Zoology, Acharya Nagarjuna University,
Nagarjunanagar 522 510, India;
(EB, elijahalc@gmail.com) Department of Zoology, Andhra Loyola College, Vijayawada 520 008, India

ABSTRACT
The genus Parvulobathynella Schminke, 1973a, presently contains six species: three each from South America and Africa. Two new
species of this genus, viz. Parvulobathynella distincta n. sp. and Parvulobathynella projectura n. sp., collected in the interstitial banks of
the Rivers Krishna and Godavari in the southeastern India, are described and illustrated and their taxonomic position in the genus
Parvulobathynella is discussed. To accommodate the Indian species, the generic diagnosis of Parvulobathynella is amended based,
among other things, on the mandibular features such as the size and arrangement of molar teeth. The salient morphologic characters and
their various states in the species of Parvulobathynella are reviewed. A note on the ecology and biogeography of the species is added.
The monophyletic status of the family Leptobathynellidae is also briefly discussed.
KEY WORDS: Bathynellacea, Leptobathynellidae, Parvulobathynella, stygofauna
DOI: 10.1651/10-3435.1

INTRODUCTION paper, besides giving an illustrated description of the two

new species, evaluates the morphologic characters and their
Out of over 250 species and subspecies of the order
various states in the species of this genus. Amongst the
Bathynellacea Chappuis, 1915, only 11 species are
mandibular characters, the size and arrangement of molar
described from India until now, which include eight species
teeth are found to be highly unique to the genus, the
of the genus Habrobathynella Schminke, 1973a, one
diagnosis of which is amended to accommodate the new
species each of Atopobathynella Schminke, 1973a, and
Indian species. The phylogenetic relationships of Lepto-
Chilibathynella Noodt, 1963a, all belonging to Parabathy-
bathynellidae vis-à-vis Parabathynellidae are briefly dis-
nellidae Noodt, 1965, and one species of Serbanibathynella
cussed. Also, notes on the ecology and the biogeography of
Ranga Reddy and Schminke, 2005 in Bathynellidae
the species of Parvulobathynella are added.
Grobben, 1904. With the exception of the cave-dwelling
Chilibathynella, all the Indian taxa inhabit the coastal
deltaic belt of the Rivers Krishna, Godavari, and Pennar in MATERIAL AND METHODS
the southeastern peninsular India. The specimens studied were sorted from core samples collected from the
Parvulobathynella Schminke, 1973a, belongs to Lepto- sandy river banks. A rigid PVC tube (length c. 70 cm, diameter 11 cm) was
bathynellidae Noodt, 1965, as resurrected by Serban used for coring. The cores, taken from the sediment surface to a depth of
(1980). Following Cho and Schminke (2001), this genus 30-50 cm, were pooled in a bucket and stirred well with habitat water. The
contains six species: P. ypacaraiensis (Noodt, 1963b), P. supernatant was filtered through bolting-silk plankton net (mesh size
70 mm), and the filtrate fixed in 5% formaldehyde.
riegelorum (Noodt, 1965), P. camposicola (Jakobi, 1961), Specimens were sorted into 70% alcohol and later transferred into
P. pentodonta (Serban and Coineau, 1982), P. duodecima glycerol. Dissection was carried out in glycerol under a binocular
Cho and Schminke, 2001, and P. octacantha Cho and stereomicroscope at a magnification of 903. Drawings were made with
Schminke, 2001. While the first three species are known the aid of a drawing tube mounted on a Leica DM 2500 Trinocular
Research Microscope, equipped with UCA condenser, IC objective prism
from South America, the last three are from Africa. and 1-23 magnification changer. Permanent preparations were mounted
Investigations under the auspices of an ongoing major in glycerol. The type material of Parvulobathynella distincta n. sp. is
research project on the biodiversity of subterranean deposited in the National Zoological Collections of the Zoological
groundwaters of India, with special reference to Copepoda Survey of India, Kolkata, India, and also in the National Museum of
and Bathynellacea, have yielded two new bathynellacean Natural History, Paris (Muséum national d’Histoire naturelle, prefix
MNHN), and that of Parvulobathynella projectura n. sp. in the latter
species, which can be assigned to Parvulobathynella. The repository.
new species were collected in the interstitial banks of the Abbreviations used in the figures of the male thoracopod VIII: bexp 5
Krishna and Godavari Rivers in the southeastern India. This basexopod; dlb 5 dentate lobe; enp 5 endopod; and ilb 5 inner lobe.

485
486 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Fig. 1. Map showing the distribution of Parvulobathynella distincta n. sp. and P. projectura n. sp. in India.

SYSTEMATICS on proximal endite and 5 claws and 2 weak outer setae on

distal endite. Maxilla 2- or 3-segmented, with strong
Order Bathynellacea Chappuis, 1915
terminal claw. Uropodal endopod with 3 setae and 1 large
Leptobathynellidae Noodt, 1965
distinct spine and 1 small spine. Pleotelson without setae.
Parvulobathynella Schminke, 1973a Type species: Parvulobathynella ypacaraiensis (Noodt,
Amended Diagnosis.—Molar teeth of mandible moderately 1963)
large, similar in size and lying as a group but with narrow Other species: P. riegelorum (Noodt, 1965), P. camposicola
interspaces; tooth of ventral edge slightly smaller than or (Jakobi, 1961), P. pentodonta (Serban and Coineau, 1982), P.
equal to molar teeth and occurring either close to pars duodecima Cho & Schminke, 2001, P. octacantha Cho &
molaris or almost halfway between pars molaris and pars Schminke, 2001, P. distincta n. sp., and P. projectura n. sp.
incisiva; palp originating at about the level of tooth of
ventral edge. Male thoracopod VIII rod-like or rectangular Parvulobathynella distincta n. sp.
in shape; basis with 1 seta; dentate lobe smooth or (Figs. 2-7)
denticulate, sometimes protruded. Caudal furca rounded
terminally and armed with 1 large terminal and 2 small Type Locality.—River Godavari at Kapileswarapuram
inner spines. Labrum generally spinulose; spinules mostly (16u47928.50N, 82u03933.80E; elevation 34.3 m; tempera-
backwardly directed. Antennule and antenna 6- and 5- ture 24uC; pH 7.0), which is 35 km from Rajahmundry
segmented, respectively. Maxillule with 4 spiniform setae town, South India.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 487

Fig. 2. Parvulobathynella distincta n. sp., paratype female. A, habitus, lateral. B, head, ventral.
488 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Fig. 3. Parvulobathynella distincta n. sp., A, C-E, I-K, Holotype female. B, Allotype male and F-H, L, paratype female. A, antennule, dorsal. B, first
segment of antennule, lateral. C, antenna, ventral. D, labrum, ventral. E, mandible, lateral. F-G, pars molaris, lateral. H, pars incisiva, dorso-lateral. I,
paragnaths, ventral. J, maxillule, lateral. K-L, maxilla, lateral.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 489

Fig. 4. Parvulobathynella distincta n. sp., holotype female. A-E, Th. I-V.

490 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Fig. 5. Parvulobathynella distincta n. sp., A-D, holotype female, E-F, paratype female. A-B, Th. VI-VII. C, Th. VIII, ventral. D-F, Th. VIII, lateral.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 491

Fig. 6. Parvulobathynella distincta n. sp., A, holotype female. B-C, paratype female. A, pleotelson, ventral. B, same, lateral. C, uropod, dorsal.
492 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Fig. 7. Parvulobathynella distincta n. sp., A-E, Th. VIII, allotype male. A, latero-external. B, latero-internal. C, posterior. D, anterior. E, ventral.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 493

Material Examined.—Holotype female, dissected on 8 Antenna (Fig. 3C): 5-segmented, bent backwards be-
slides (C5870/2/a-h); allotype male, whole-mounted on 1 tween segments 1 and 2, extending up to midlength of head,
slide (C5871/2); 1 female paratype, dissected on 8 slides in lateral view (Fig. 2A) and reaching 83% of antennular
(C5872/2/1i-viii/a-h); 2 female paratypes dissected on 3 length. Combined length of segments 1-3 equalling that of
slides each (C5872/2/2i-iii/a-c; C5872/2/3i-iii/a-c); and 1 segments 4-5. Second segment armed with 1outer seta.
female paratype whole-mounted on 1 slide (C5873/2); Third and fourth segments subequal in length, each with 1
deposited in the National Zoological collections of the long simple seta at inner distal corner. Fifth segment with 2
Zoological Survey of India, Kolkata. Five undissected terminal simple setae and 1 thick subterminal plumose seta.
female paratypes, preserved in alcohol (MNHN-Sy53); 1 Labrum (Fig. 3D): small, elliptical in outline, carrying
female paratype, whole-mounted on 1 slide (MNHN-Sy54); 10 long, somewhat curved and backwardly directed
1 female paratype, dissected on 3 slides [(MNHN-Sy55(a- spinules; medial spinules longer than lateral ones.
c)]; 1 male paratype, dissected on 3 slides [(MNHN- Mandible (Fig. 3E-H): pars incisiva with 4 teeth,
Sy56(a-c)]; deposited in the National Museum of Natural proximal-most tooth lying opposite to the rest. Tooth of
History, Paris; 15 October 2006. ventral edge defined at base and close to proximal-most
Other Localities: 1 female paratype, dissected on 3 slides tooth of pars incisiva. Pars molaris consisting of 3 discrete,
[MNHN-Sy57(a-c)]; 1 female, whole-mounted, and 1 somewhat unequal teeth and located away from pars
female in alcohol, in V. R. Totakura’s collection; River incisiva. Palp lying at level of tooth of ventral edge, 1-
Godavari at Dhawaleswaram (16u56978.30N, 81u46970.20E; segmented, with 1 simple seta about 5 times as long as
elevation 40.3 m; temperature 27uC; pH 7.5) in East palp.
Godavari District, Andhra Pradesh, South India, 20 July Paragnaths (Fig. 3I): subtriangular, with a slight projec-
2008. Twenty-three female and 2 male paratypes in alcohol tion on each side distally.
in 1 vial (MNHN-Sy64) and 15 females in V.R. Totakura’s Maxillule (Fig. 3J): proximal endite small, slightly
collection; River Godavari at Atreyapuram village (tem- longer than wide, with 4 claw-like similar terminal spines.
perature 27uC; pH 7.0) in East Godavari District, Andhra Distal endite slender and subcylindrical, 3 times as long as
Pradesh, South India, 20 July 2008 (Fig. 1). All material wide, with 2 long claws (1 terminal and 1 subterminal), 3
collected by V. R. Totakura. unequal inner claws and 2 unequal simple setae on outer
distal margin.
Diagnosis.—Uropodal sympod 3 times as long as wide and
Maxilla (Fig. 3K-L): 2-segmented. Proximal segment
with 2 long similar spines. Uropodal endopod dilated and
somewhat rectangular and unarmed. Distal segment 3.3
spinulose at mid-inner margin and armed with 1 long
times as long as wide and armed with prehensile apical
subterminal spine. Labrum with 10 spinules on free margin.
claw and 9 setae, of which 1 seta occurring on small
Aesthetasc on antennular segment 5 shorter than segment 6,
proximal inner protuberance; claw slender, smooth and
and those on segment 6 equal in length. Pars incisiva of
longer than distal segment.
mandible with 4 teeth, proximal-most tooth lying opposite
Thoracopods I-VII (Figs. 4A-E, 5A-B): well developed,
to the other teeth.
length gradually increasing from Th I-IV; Th V-VII almost
Description of Adult Female (Holotype).—Total length similar in size. Th I-III without epipod. Th IV-VII each
0.60 mm. Body slender, elongate, 11 times longer than bearing 1-segmented, club-shaped epipod, about 0.6 times
maximum width (Fig. 2); cuticle thin and imperforate. In as long as basis. Basis on all thoracopods without inner
lateral view, pleomeres wider than thoracic segments. Head marginal seta. Exopod 2-segmented, as long as endopod on
1.2 times as long as wide and equalling the combined Th I and 1.3 times as long as endopod on Th II-VII. On all
length of first 2 thoracic segments. thoracopods, segment 1 of exopod with 1 barbed seta on
Antennule (Fig. 3A): 6-segmented, 33% longer than inner distal margin and 1 row of spinules; segment 2 with 1
head. Length of first 3 segments 1.7 times as long as last 3 terminal barbed and 1 subterminal plumose setae and 1 row
segments; segment 3 shortest. First segment with 1 small of spinules at base of subterminal plumose seta. Endopod 4-
simple seta at inner distal corner, 1 long dorsal simple seta segmented; segments 2 and 3 with 1 row of spinules each
subdistally and 1 small dorsal simple seta at outer distal on distal inner margin; setal formula: 0+0/0+1/0+0/2(1).
margin, 2 ventral plumose setae on subdistal outer margin. Thoracopod VIII (Fig. 5C-F): small, plate-like and
In male, 1 additional seta on dorsal surface (Fig. 3B). rounded in lateral view, but subtriangular in ventral view.
Second segment with 3 plumose setae on outer distal Pleopod 1: absent.
margin in a row and 1 ventro-medial plumose seta at Uropod (Fig. 6A): sympod 3 times as long as wide,
midlength. Third segment with 1 long simple seta and 1 bearing 2 similar, relatively long serrulate spines on
small plumose seta at outer distal corner. Inner flagellum slightly dilated inner distal margin. Exopod almost
short, somewhat rounded with 3 unequal simple setae. cylindrical, 4 times as long as wide, measuring 56% of
Fourth segment with stout apophysis overreaching mid- sympod length and armed with 1 long terminal and 1 short
length of next segment and bearing 2 slightly subequal subterminal barbed setae. Endopod nearly twice as long as
plumose setae and 1 short plumose seta beside apophysis; wide, 40% of sympod length, somewhat dilated and fringed
stub seta absent. Fifth segment with 1 simple seta, 1 with 1 row of spinules at mid-length of inner margin;
aesthetasc at outer distal corner, 2 simple setae at inner armature consisting of 3 plumose setae (1 dorso-medial, 1
distal corner. Sixth segment with 4 unequal simple setae terminal and 1 subterminal), 1 greatly reduced terminal
and 3 equal aesthetascs. spine and 1 relatively long spine at subterminal inner angle.
494 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Pleotelson (Fig. 6A): without any armature. sympod only 1.8 times as long as wide with 2 short spines;
Anal operculum (Fig. 6A): concave. endopod with very short, backwardly directed, subterminal
Caudal furca (Fig. 6A-B): subquadrate and rounded spine. Caudal furca sub-conical. Labrum smooth. All
terminally in ventral view, but conical in lateral view; armature elements of maxillule except outer setae modified
twice as long as maximum width, bearing 1 stout, into short, sturdy spines. Maxilla with distinct prominence
proximally dilated, terminal spine with finely serrulate on inner margin. Antennule with greatly reduced aesthe-
lateral margins and 2 small unequal spines on inner margin; tascs on segments 5 and 6; aesthetasc on segment 5
2 dorsal plumose setae, of which outer seta twice as long as occurring at inner instead of outer distal corner.
inner one; 1 row of fine spinules on ventral distal margin.
Furcal organ small and pointed. Description of Female (Holotype).—Total length 0.63 mm.
Body elongate, cuticle thin and imperforated, 12 times
Description of Male (Allotype).—Total length 0.53 mm. longer than maximum width (Fig. 8). Thoracic and pleonal
Body and all appendages except thoracopod VIII as in female. segments each with rounded protuberance at postero-lateral
Thoracopod VIII (Fig. 7A-E): small, somewhat obovate angle (mid-dorsal view of protuberance as shown in
in lateral views (Fig. 7A, B) and rectangular in anterior and Fig. 12A). Head 35% longer than wide and 1.4 times as
posterior views (Fig. 7C, D); 1.4 times as long as maximum long as first 3 thoracic segments combined.
width. Protopod of moderate size. Outer lobe not Antennule (Fig. 9A): 6-segmented, 12.8% longer than
discernible. Inner lobe shorter than dentate lobe. Dentate head. Length of first 3 segments 1.4 times as long as last 3
lobe smooth. Basis not defined at base and with 1 subdistal segments; segment 3 shortest. First segment with 2 ventral
seta. Exopod fused to basis, forming plate-like and apically plumose setae at outer distal corner, 1 small ventro-distal
denticulate basexopod. simple seta, 1 long dorsal simple seta in distal half and 1
ventral plumose seta subdistally. Second segment with 3
Variation.—Body size 0.59-0.68 mm in female and 0.53- dorsal plumose setae on outer distal margin and 1 ventral
0.64 mm in male. The relative size of molar teeth of plumose seta at outer distal corner. Third segment with 1
mandible is variable as shown in Fig. 3E-G. The terminal simple seta and 1 small, ventral plumose seta at outer distal
claw of maxilla (Fig. 3K-L), the uropodal exopod (Fig. 6A, corner. Inner flagellum somewhat rectangular with 3
C) and the female Th. VIII (Fig. 5D-F) are subject to some unequal simple setae. Fourth segment with stout apophysis
variation in shape, as illustrated. overreaching mid-length of next segment and carrying 2
Etymology.—The specific epithet alludes to the unusual unequal plumose setae and 1 long plumose seta beside
position of the proximal-most tooth of pars incisiva of the apophysis. Fifth segment with 1 simple seta at outer distal
mandible; derived from the Latin adjective distinctus 5 corner, 1 long ventral seta on distal margin, 1 short seta and
distinct. The name agrees in gender with the (feminine) 1 small aesthetasc at inner distal corner. Sixth segment with
generic name. 4 long, terminal simple setae and 3 tiny but equal
aesthetascs at outer distal corner.
Antenna (Fig. 9B): 5-segmented, bent backwards, extend-
Parvulobathynella projectura n. sp. ing up to mid-length of head in lateral view and reaching
(Figs. 8-13) 68% of antennular length. Combined length of segments 1-3
equalling that of segments 4-5. Second segment with 1 small
Type Locality.—River Godavari at Kotipalli village seta at outer distal corner. Third segment somewhat dilated
(16u41933.50N, 82u03945.50E; elevation 10.8 m; tempera- and subequal to segment 4 in length, each with 1 long simple
ture 28uC; pH 7.5) in East Godavari District, Andhra seta at inner distal corner. Segment 5 with 2 terminal simple
Pradesh, South India. setae and 1 thick subterminal plumose seta.
Labrum(Fig. 9C): broadly triangular in outline; free
Material Examined.—Holotype female, dissected on 3
margin smooth, produced in ventral view but folded in
slides [MNHN-Sy58(a-c); allotype male, dissected on 3
dorsal view (Fig. 9D).
slides [MNHN-Sy59(a-c)]; 4 female paratypes: 1 female
whole-mounted (MNHN-Sy60), 3 females (dissected on 3 Mandible (Fig. 9E-F): pars incisiva with 3 teeth; position
slides each) in V. R. Totakura’s collection, 13 March 2008. of proximal-most tooth normal. Tooth of ventral edge
Three female paratypes, dissected on 3 slides each defined at base and located halfway between pars molaris
[MNHN-Sy61(a-c), MNHN-Sy62(a-c), MNHN-Sy63(a- and pars incisiva. Pars molaris consisting of 3 unequal teeth
c)], 6 females in alcohol in 1 vial (MNHN-Sy65), River in a group but with narrow interspaces; distinct gap present
Godavari, Kotipalli village (16u41933.50N, 82u03945.50E; between pars molaris and pars incisiva. Palp lying at the
elevation 10.8 m; temperature 23uC; pH 7.5), East level of tooth of ventral edge, 1-segmented, carrying 1
Godavari, Andhra Pradesh, South India, 04 March 2008. long, simple seta, 2.5 times as long as palp.
Eight females in V. R. Totakura’s collection, River Paragnaths (Fig. 9G): as in P. distincta n. sp. except for
Godavari, Kotipalli village (16u41933.50N, 82u03945.50E; disto-lateral projections being shorter.
elevation 10.8 m; temperature 24uC; pH 7.5), East Maxillule (Fig. 9H-I): proximal endite small, 1.5 times
Godavari, Andhra Pradesh, South India, 30 April 2008 as long as wide, with 4 short, blunt spines at inner distal
(Fig. 1). All material collected by V. R. Totakura. corner. Distal endite slender, subcylindrical, twice as long
as wide and armed with 2 terminal and 3 inner short,
Diagnosis.—Thoracic and abdominal segments each with modified claws and 2 slightly unequal simple setae on outer
rounded protuberance at postero-lateral angle. Uropodal distal margin.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 495

Fig. 8. Parvulobathynella projectura n. sp. paratype female, habitus.

496 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Fig. 9. Parvulobathynella projectura n. sp., A-C, E, H, J, holotype, female. D, F-G, I, paratype, female. A, antennule, dorsal. B, antenna, lateral. C,
labrum, ventral. D, same, dorsal. E, mandible, dorso-lateral. F, same, ventro-lateral. G, paragnaths, ventral. H, maxillule, lateral. I, same, dorsal. J,
maxilla, lateral.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 497

Fig. 10. Parvulobathynella projectura n. sp., holotype female. A-E, Th. I-V.
498 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Fig. 11. Parvulobathynella projectura n. sp., A-C, holotype female. D-E, paratype female. A-B, Th. VI-VII. C-E, Th. VIII, lateral. F, same, ventral.

Maxilla (Fig. 9J): 2-segmented. Proximal segment un- Pleopod 1: absent.

armed. Distal segment 3 times as long as wide and armed Uropod (Fig. 12A-B): sympod stout, 1.8 times as long as
with prehensile apical claw and a total of 9 setae, of which wide and with 2 short similar spines on distal inner margin.
1 seta occurring on a distinct proximal inner protuberance; Exopod cylindrical, 3 times as long as wide, 73% of
claw sturdy, shorter than distal segment, and distal third of sympod length, bearing 1 terminal and 1 subterminal
inner margin with tiny spinules. barbed setae. Endopod oblong in outline, about as long as
Thoracopods I-VII (Figs. 10A-E, 11A-B): as in P. exopod, only slightly dilated and fringed with 1 row of
distincta. spinules at midlength of inner margin; armature consisting
Thoracopod VIII (Fig. 11C-F): small and crescentic in of 3 plumose setae (1 dorso-medial, 1 terminal and 1
lateral view and somewhat conical in ventral view subterminal), 1 greatly reduced terminal spine and 1 very
(Fig. 11F). short, posteriorly directed spine at subterminal inner angle.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 499

Fig. 12. Parvulobathynella projectura n. sp., A, holotype female. B-C, paratype, female. A, pleotelson, lateral. B, pleotelson, ventral. C, anal
operculum, dorsal.
500 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

noun projectura 5 bulge, protuberance. The name agrees

in gender with the (feminine) generic name.

DISCUSSION
Interspecies Relationships
(Table 1)
Before discussing the relationships of the two new
species within Parvulobathynella, it is necessary to explain
why the diagnosis of this genus has to be amended. This
genus was established by Schminke (1973a) for three South
American species, viz., P. ypacaraiensis (type species), P.
camposicola, and P. riegelorum. Its original definition
reads (in translation) thus: ‘‘Maxillule with 4 short, equal
setae on a rudimentary projection of proximal endite; distal
endite with 5 claws, of which the distal 3 in one group, the
other 2 distinctly proximal, and outer margin with 2 weak
setae. Maxilla two-segmented, prehensile, with 1 strong
terminal claw; proximal segment with 1 inner marginal seta
[sic]. Mandible with 4 small teeth proximal of pars incisiva.
Labrum with smooth or setaceous free margin. Antenna
five-segmented, segment 2 with or without [sic] outer
marginal seta. Furca rounded terminally, with 1 terminal
spine and 2 spines or rather setae on inner margin.
Antennule six-segmented. Uropodal endopod with 1-2
articulate spines. Pleotelson without setae.’’ Note that all
the original principal criteria of Parvulobathynella are
Fig. 13. Parvulobathynella projectura n. sp., A-D, Th. VIII, allotype essentially the same as those of the other five genera of
male. A, latero-external. B, latero-internal. C, anterior. D, posterior. Leptobathynellidae except for some differences in the
armature elements of the maxillule (Table 2).
Pleotelson (Fig. 12A-B): without setae. Cho and Schminke (2001), when describing two new
Anal operculum (Fig. 12A, C): slightly concave. species from South Africa besides redescribing the South
Caudal furca (Fig. 12A-B): sub-conical in dorsal view, American P. ypacaraiensis and P. riegelorum, rightly
1.2 times as long as maximum width, with 2 plumose setae observed that the original definition of Parvulobathynella
on dorsal surface, 2 spines on inner margin and 1 spine on was based ‘‘solely on plesiomorphic characters.’’ Accord-
the apex; 1 row of fine ventral spinules at the base of ingly, the same authors underscored the following charac-
terminal spine and 1 row of larger ventral spinules close to ters as diagnostic of the members of Parvulobathynella: 1)
proximal inner spine. Furcal organ small and pointed. pars incisiva is ‘‘distinct’’ from the rest of the mandible, 2)
maxilla has a prehensile claw, 3) male thoracopod VIII is
Description of Male (Allotype).—Total length 0.62 mm. ‘‘rod-shaped,’’ 4) uropodal sympod has two diagonally
Body and all appendages except thoracopod VIII as in arranged spines, and 5) labrum is ‘‘setaceous.’’ And yet, the
female. two new Indian species bring into question the reliability of
Thoracopod VIII (Fig. 13A-D): relatively small, some- all these characters as generic criteria and hence the
what obovate in latero-external and latero-internal views amendment of the genus definition.
(Fig. 13A, B) and rectangular in anterior and posterior Initially, we mistook the two new Indian species for the
views (Fig. 13C, D); 1.5 times as long as maximum width. members of the closely related Neotropical genus Brasili-
Protopod of moderate size; outer lobe not discernible; inner bathynella Jakobi, 1958, because the existing morphologic
lobe small, conical, shorter than dentate lobe. Dentate lobe gap between this genus and Parvulobathynella is rather
balloon-like in latero-external view (Fig. 13A), broad and narrow. However, a detailed study of the mandible and
plate-like with minute denticles apically in anterior and labrum has revealed that the new taxa can more correctly
posterior views (Fig. 13C-D). Basis fused to protopod and be assigned to Parvulobathynella but in an amended form
with 1 subdistal seta. Exopod fused to basis, forming (see above). For the time being, it is advisable to maintain
basexopod, which is plate-like and denticulate apically. the status quo of these two genera on the basis of the subtle
Variation.—Body size of female 0.58-0.63 mm, mean 0.62 differences in the mandibular details, the number of
(n 5 6). The shape and size of the female Th VIII also vary endopodal segments on thoracopod I, and the armature of
but slightly (Fig. 11C-E). uropodal endopod (see also Table 2).
As one would expect, P. distincta and P. projectura
Etymology.—The specific epithet alludes to the protuber- are more closely related to each other than to the
ance at the postero-lateral angle of each of the thoracic and South American and African congeners. The chief points
abdominal segments of the body; derived from the Latin of resemblance between the two Indian species are:
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 501

Fig. 14. Biogeographical distribution of the currently recognized species of Parvulobathynella.

1) uropodal endopod has only a single row of spinules at puny slender body is no doubt a decisive advantage for
mid-length of the inner margin, 2) aesthetascs on the interstitial mode of life; but then it is characteristic not only
antennular segment 6 are equal in size, 3) maxilla has nine of Parvulobathynella, but also of almost all other taxa of
instead of ten setae, and 4) thoracopod VIII female is the Leptobathynellidae – arguably the most derived
primitively large. Also, the mandible has a reduced number assemblage in Bathynellacea. At the other end of the
of either three or four teeth on pars incisiva. Within body-size spectrum is the Australian Billibathynella hum-
Leptobathynellidae, P. distincta stands out by the proximal- phreysi Cho, 2005 – as yet the most primitive parabathy-
most tooth of pars incisiva lying opposite to the other three nellid, with a body length of 6.3 mm. According to Noodt
teeth just like the human thumb versus fingers. The other (1965), the enormous body size might have developed
relationships can be understood from Table 1. secondarily in adaptation to free water.
Morphologically, the species of Parvulobathynella So far, the nature of the integument has not been
constitute an extremely homogeneous group within Bath- described for most bathynellaceans. Generally the integu-
ynellacea. We have, therefore, reviewed here the chief ment, both of the body and limbs, is thick owing to heavy
morphologic characters and their various states in seven chitinisation in most Parabathynellidae whereas it is thin in
species of Parvulobathynella including the Ivorian P. Bathynellidae (Schminke, personal communication). Both
pentodonta (Serban and Coineau, 1982) and the two new P. distincta and P. projectura have thin integument. It is
Indian congeners. [Parvulobathynella camposicola with its worth investigating whether the habitat factors such as
rather incomplete original account is a ‘species inquirenda’ sand-grain size are related to the nature of the integument.
so it is not considered here for comparison.]
Antennule.—The first segment bears an additional dorsal
Body Size and Integument.—As the stem of the generic seta in the males of all the species except P. projectura and
term Parvulobathynella suggests, the animals are small in perhaps P. pentodonta. Invariably, the fifth and sixth
size, being less than 1 mm in body length (Table 1). This segments have 1 and 3 aesthetascs, respectively, but the
 502

Table 1. Comparison of morphological features of Parvulobathynella ypacaraiensis, P. riegelorum, P. duodecima, P. octacantha, P. pentodonta, P. distincta n. sp., and P. projectura n. sp. aes 5
aesthetasc(s); seg 5 segment.

P. ypacaraiensis P. riegelorum P. duodecima P. octacantha P. pentodonta P. distincta n. sp. P. projectura n. sp.

Author description Cho and Schminke, Cho and Schminke, Cho and Schminke, Cho and Schminke, Serban and Coineau, Present study Present study
2001 2001 2001 2001 1982
Total body length: range in mm
= 0.6-0.8 0.5-0.7 0.63 0.65 0.65-0.80 0.52-0.65 0.62
R 0.6-0.8 0.5-0.7 0.62-0.63 ? ? 0.59-0.68 0.58-0.63
Antennule
Additional dorsal seta on seg 1 of = present present absent present ? present absent
Apophysis length vs. seg 5 0.5 0.7 0.5 0.6 0.8 0.8 0.8
Length of aes on seg 5 vs. seg 6 longer longer longer shorter longer shorter much shorter
Relative lengths of aes on seg 6 unequal unequal unequal unequal unequal equal equal
Labrum
No. of spinules 28 24 12 18 21 10 0
No. of lateral teeth 2 2 2 2 0 0 0
Mandible
Nature of pars incisiva notched vaguely notched fused fused fused fused fused
No. of teeth on pars incisiva 5 5 5 5 5 4 3
Orientation of proximal-most tooth
vs. other teeth
Proximal tooth of pars molaris parallel parallel parallel parallel parallel perpendicular parallel
bifurcate simple with denticle bifurcate bifurcate simple simple
Maxillule
Armature on proximal endite 4 spiniform setae 4 spiniform setae 3 spiniform setae 3 spiniform setae 4 spiniform setae 4 spiniform setae 4 short spines
+ 1 short spine + 1 short spine
Armature on distal endite 5 claws, 2 setae 5 claws, 2 setae 5 claws, 2 setae 5 claws, 2 setae 5 claws, 2 setae 5 claws, 2 setae 5 spines, 2 setae
Maxilla
JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

Seg 3 and terminal claw distinct distinct distinct distinct fused fused fused
No. of setae on seg 2 (& 3) 10 10 10 10 10 9 9
Inner protuberance on seg 2 vague absent absent small absent small large
Thoracopod III
Epipod absent present present absent present absent absent
Thoracopod VIII =
Dentate lobe smooth, not smooth, not smooth, smooth, smooth, not smooth, not denticulate, not
protruded protruded protruded protruded protruded protruded protruded
Exopod ? ? ? ? smooth denticulate denticulate
Thoracopod VIII R shape ‘‘stub’’ ‘‘stub’’ ‘‘stub’’ ? finger-like subtriangular crescentic
Caudal furca
Length/maximum width 1.5 1.7 2.1 1.5 1.8 2.1 1.2
Inner spines: proximal vs. distal shorter equal equal shorter Shorter shorter equal
Length of terminal spine vs. distal 13 23 23 23 1.33 1.63 1.83
inner spine
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 503

India, Andhra Pradesh,

relative lengths of the aesthetascs vary between the species

River Godavari at
P. projectura n. sp.
(Table 1). All the aesthetascs in P. projectura are strikingly
reduced in size. The fourth segment bears apophysis of

distinct
2.1:1
1.8
varying length not only in species of Parvulobathynella,

Kotipalli
but also in all other taxa of Leptobathynellidae as well.
Antenna.—The segmentation, relative lengths of the
segments and their setation are similar in all the species

Kapileswarapuram
of Parvulobathynella, as in the Cteniobathynella-group
P. distincta n. sp.

Pradesh, River
(exception two-segmented in Habrobathynella) (see
distinct

Godavari at
India, Andhra
1.1:1
3

Drewes and Schminke, 2007). The segments, however,

are relatively dilated in P. projectura.
Labrum.—Schminke (1973a) recognised three types of
labra in Parabathynellidae based on the nature of their free
Ndouci and Lamto

margin: dentate, setaceous, and smooth. [Here the term

P. pentodonta

‘spinulose’ is more appropriate than ‘‘setaceous’’ to

River between
Ivory Coast, Nzi
fused
1.5:1

describe the diminutive spines, which are only rigid

3

cuticular elements without ‘a hollow central core.’]

According to Cho and Schminke (2001), the ‘‘setaceous’’
labrum can be treated as a synapomorphic feature of
Parvulobathynella. However, P. projectura has a perfectly
smooth labrum – perhaps the most derived condition in this
Natal, sandbank
at Sandspruit, a
P. octacantha

genus. Cho (1995) also observed ‘‘different conditions’’ in

distinct
1.6:1
South Africa,

the chaetotaxy of the labra in Parvulobathynella as well as

3

stream

Leptobathynella.
Mandible.—The pars incisiva is notched but not ‘‘distinct
from the rest of the mandible’’ in Parvulobathynella
ypacaraiensis, whereas it is completely fused to the
Clanwilliams and
P. duodecima

mandibular body in all other species including the Indian

Kaapprovinsie,
Olifants River
distinct
1.7:1

congeners. As already mentioned, the proximal-most tooth

2.9

South Africa,

between

of pars incisiva in P. distincta is unique in that it lies

Klawer

perpendicular to the other teeth.

Maxillule.—The armature is essentially the same in all
species of Parvulobathynella except that the distalmost seta
Peralillo, sandbank

on the first endite of P. duodecima and P. octacantha is

of Rio Chopa, a
P. riegelorum

Chile, Fundo El
distinct

transformed into a short spine. Parvulobathynella projec-

1.6:1
2.9

tura shows an interesting character state in that all the

armature elements save the outer setae of the second endite
stream

are modified into short, sturdy claw-like structures,

somewhat reminiscent of the condition seen in Acantho-
bathynella knoepffleri Coineau, 1967. The number of
armature elements on the proximal and distal endites and
P. ypacaraiensis

Lake Ypacarai
distinct

sandbank of

also the origin of the outer setae on distal endite show

Paraguay, San
Bernardino,
1.4:1
3.2

certain differences between the leptobathynellid genera

(Table 2). Further studies are needed to establish whether
these differences are really valid at genus level.
Maxilla.—All the genera of Leptobathynellidae are char-
acterised by a terminal prehensile claw as well as an
Sympod length/ maximum width

unarmed proximal segment, another synapomorphy of the

Length of endopod vs. spur
Identity of spur of endopod

family. Generally, the claw is longer than or equal to the

second segment, but it is clearly shorter in P. projectura.
Biogeography and habitat

Also, the claw is either distinct from or fused to the third

Table 1. Continued.

segment (Table 2). The second segment bears one seta at

about its mid-inner margin, the point that corresponds to
the junction between the ancestral segments 2 and 3; this
seta is borne on a distinct protuberance in P. projectura, a
Uropod

plesiomorphy. The size of the protuberance varies between

the species (Table 1).
 504

Table 2. Principal morphologic differences between the genera of the Leptobathynellidae.

Lepto-bathynella Brasili-bathynella Parvulo-bathynella Acantho-bathynella Odonto-bathynella Califo-bathynella

Author description Noodt, 1972 Schminke, 1973a Cho and Schminke, 2001 Coineau and Serban, 1973 Delamare and Serban, 1979 Cho, 1997
Chaetotaxy normal normal normal modified normal normal
Antenna
Inner seta on segment 2 present? absent present absent absent present
Labrum
Ornamentation of free ? spinulose generally smooth dentate dentate/spinulose
margin
spinulose
Mandible
Size of pars incisiva small small small large large small
Tooth of ventral edge small large small small large small
Rudiment of pars molaris absent absent absent present absent absent
Position of palp opposite to tooth of opposite to pars molaris opposite to tooth of below pars incisiva opposite tooth of opposite tooth of
ventral edge ventral edge ventral edge ventral edge
Maxillule
Proximal endite 1 4 4 4 2 1
No. of armature elements 4 5 5 5 5 5
Distal endite outgrowth margin margin margin margin margin
No. of claws
Origin of outer setae
Maxilla
JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

No. of segments 2 2 3-Feb 2 2 3

Mid-inner seta of segment 2 present? absent present present present absent
Thoracopod I
No. of endopodal segments 4 3 4 4 4 4
Uropod
Exopodal setae 2 2 2 2 3 2
Endopodal armature elements 5 3 5 3 3 4
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 505

Thoracopods I-VII.—Epipod is present on thoracopod III in well. This is in sharp contrast to Habrobathynella wherein
P. riegelorum, P. duodecima, and P. pentodonta, but it is the ten known congeners display five distinct character
absent in other species. Otherwise there are no definitive states of the spine row (Ranga Reddy and Totakura, 2010).
species-specific differences. In general, the segmentation as Regarding the arrangement of sympod spines, it must be
well as armature of thoracopods I-VII is identical in all the pointed out that both spines generally appear to be diagonal
leptobathynellid genera barring Brasilibathynella, in which in the lateral view, but in a straight line in the dorsal view
the endopod of thoracopod I has only three segments of the uropod. Hence, insofar as Leptobathynellidae, the
instead of four. armature elements and their arrangement on the uropodal
sympod are of little diagnostic help at genus level and, to a
Thoracopod VIII, Male.—This complex penile appendage large extent, at species level as well.
is greatly reduced in size. Hence, to discern the subtle The uropodal exopod is somewhat slenderer than
details of its various component parts is indeed a tricky job. endopod and armed with two setae, one apical and one
For most species the details of this appendage are subapical, in all the taxa of Leptobathynellidae except O.
incomplete. However, based on the published figures and amazonica, which has three setae, one proximal and two
descriptions, we briefly deal with the important characters apical. This is yet another plesiomorphic feature of
and their various states. Odontobathynella. The number of armature elements on
With protopod being large and elongate, this appendage the uropodal endopod varies between three and five in the
is somewhat ‘‘rod-like’’ or rectangular, but the shape could leptobathynellid genera (Table 2). In most of the para-
widely vary between the congeners. In both the new bathynellid taxa, the uropodal endopod is drawn out into a
species, the appendage is either rectangular or oval dagger-shaped spinous process (‘‘spur’’), which is appar-
depending on the angle of view. So is the shape in ently a primitive character state. Within Parvulobathynella,
Leptobathynella richerti brasiliensis Noodt, 1972 as well as a similar primitive condition is seen only in P. pentodonta
Odontobathynella amazonica Delamare Deboutteville and whereas all other species have a distinct spine (Table 1).
Serban, 1979. The outline of the appendage is somewhat
conical in Acanthobathynella knoepffleri. All in all, the Caudal Furca.—The armature of the caudal furca, consisting
shape of the male thoracopod VIII cannot be considered a of one large terminal spine and two small inner spines, is the
reliable generic criterion. same in all the taxa of the Leptobathynellidae. However, the
The basis is completely fused to the protopod and armed shape of the furca and the relative size and position of the
with a thick seta subdistally; no ornamentation is spines are somewhat different between the genera. For
discernible. The basial seta also exists in O. amazonica example, the furca are terminally rounded in Leptobathy-
and A. knoepffleri, but its reported absence in Leptobathy- nella, Parvulobathynella and Califobathynella but rectangu-
nella and Califobathynella (see Noodt, 1972; Cho, 1997) lar in Acanthobathynella with all the three spines occurring
needs to be verified. terminally, and so on. Unlike its congeners, P. projectura has
The inner lobe is shorter than the dentate lobe and, as conical furca, closely resembling the condition seen in
usual, smooth. The dentate lobe (‘‘middle lobe’’ of Cho and Brasilibathynella.
Schminke, 2001) is smooth in all the species except P.
projectura and protruded to form a prominent ‘‘finger-like’’ Leptobathynellidae and Phylogenetic Considerations
process in P. duodecima and a moderate conical structure
in P. octacantha. The dentate lobe is also smooth in O. Noodt (1965), while establishing Leptobathynellidae for
amazonica and A. knoepffleri, but protruded and ornament- the Neotropical Leptobathynella Noodt, 1963b and Brasi-
ed with an apical spinule in the latter species. libathynella Jakobi, 1958, discussed in detail its relation-
The outer lobe is not discernible in the two Indian ship with the other two families, Bathynellidae and
species of Parvulobathynella. Nothing of it is known in the Parabathynellidae. Subsequently, Leptobathynellidae was
other congeners. It is, however, well delineated in O. synonymised with Parabathynellidae by Schminke (1973a)
amazonica. on the premise that ‘‘some African species revealed their
The exopod is completely fused to the basis and not nature as intermediate forms’’ between these two families.
chitinised as in Habrobathynella (see Ranga Reddy and Alternatively, Schminke (1973a) created a subgroup-
Totakura, 2010). In the two new species, it is plate-like and Leptobathynella for the above two genera plus Parvulo-
apically denticulate. No details of the congeners are bathynella Schminke, 1973a, and Acanthobathynella Co-
available for comparison. The endopod is apparently ineau, 1967. According to Schminke (1973a), the genera of
absent. this subgroup together with those of another subgroup-
Cteniobathynella-Habrobathynella of the Cteniobathy-
Uropod.—Generally, the sympod is about three times as nella-group, now consisting of 14 genera in all (see Drewes
long as its maximum width in all the species except P. and Schminke, 2007), represent a distinct lineage within
projectura, in which it is only 1.8 times as long as wide, Parabathynellidae. However, having been convinced of
perhaps representing a derived state. However, within Noodt’s (1965) rationale, Coineau and Serban (1973,
Leptobathynellidae, an identical situation can be seen in 1978), and Delamare Deboutteville and Serban (1979)
Califobathynella. Invariably, the sympod spine row con- consistently maintained the validity of Leptobathynellidae.
sists only of two generally similar spines (exception: Interestingly, even as Coineau and Serban (1973) created a
dissimilar spines in P. pentodonta) not only in Parvulo- new subfamily (Acanthobathynellinae) within the Lepto-
bathynella, but also in all other leptobathynellid genera as bathynellidae, Cho (1997) relegated the family to the
506 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 31, NO. 3, 2011

subfamily-level (Leptobathynellinae), without providing The tooth of ventral edge is also small and blunt. The molar
any reason. It was Serban (1980) who elegantly explained teeth are set far apart from those of the pars incisiva.
the uniqueness of the mandibular morphology of this In Odontobathynella, the pars incisiva is large as in
family vis-à-vis the other two families. Acanthobathynella, but the lobe of pars molaris is typically
This issue of the monophyletic status of Leptobathynel- absent. The molar teeth are very large, subequal, acutely
lidae and Parabathynellidae is a critical one. pointed and lie close to each other, forming a group that is
First, let us take up the case of Leptobathynellidae, which only a wee bit away from the larger tooth of ventral edge.
now contains the following six genera: Leptobathynella, Next in the evolutionary line is Brasilibathynella as
Brasilibathynella, Parvulobathynella (synonym: Lamto- evident from: 1) the teeth of pars molaris are close-set in a
bathynella Serban and Coineau, 1982), Acanthobathynella, group, lying just beside, and in line with, those of pars
Odontobathynella Delamare Deboutteville and Serban, incisiva; 2) the tooth of ventral edge is larger than the rest;
1979, and Califobathynella Cho, 1997. The close kinship and 3) the palp lies opposite to pars molaris. Despite its
of these genera is revealed by the mandibular details, close affinities with Brasilibathynella, Parvulobathynella is
prehensile maxilla, and armature of thoracopods I-VII, distinct in certain respects: 1) the teeth of pars molaris are
uropod and caudal furca. The chief morphologic differences moderately large, equal in size, and occurring as a group
between the genera are listed in Table 2. Biogeographically, with narrow interspaces; 2) the tooth of ventral edge is
all the genera except Califobathynella are distributed on same as the molar teeth in size but lies halfway between
Gondwana landmasses (see Biogeography). pars molaris and pars incisiva; and 2) the palp lies almost at
It cannot be overemphasized that the appendages of the level of the tooth of ventral edge.
mastication (mandible) and copulation (thoracopod VIII In all these and other characters, Lamtobathynella is not
male) are of utmost importance in establishing the different from Parvulobathynella so its synonymisation
supraspecific taxa. Unfortunately, as far as Leptobathynel- with the latter by Cho and Schminke (2001) is in order. It is
lidae is concerned, it is impossible at this juncture to draw now clear that Califobathynella is barely distinguishable
any sensible phylogenetic conclusions based on the penile from Parvulobathynella by the mandibular morphology
appendage, which is rather poorly characterised or even (see below). So, further research is essential to establish
undescribed in several taxa. On the other hand, enough whether Parvulobathynella and Califobathynella are in-
light has already been shed by the previous workers (see deed distinct from Leptobathynella.
below) on the phylogenetic value of the mandibular Now, to identify the other leptobathynellid autapomor-
morphology and anatomy. phies, Cteniobathynella [type species C. leleupi (Delamare
Even the subtle mandibular differences in the number, and Chappuis, 1955)] may be reckoned as the sister group
size, and arrangement of teeth could have far-reaching of Leptobathynellidae because both these taxa have a five-
implications in the mastication process. That is why Noodt segmented antenna with identical armature and a mandible
(1965) called attention to the phylogenetic significance of of only three molar teeth. The mandibular teeth, however,
the bathynellacean mandible. Subsequently, its evolution occur on a distinct lobe in C. leleupi, an unequivocal
and homologies were briefly dealt with by Schminke plesiomorphy. Regarding the maxillule, the leptobathynel-
(1972b). Serban (1980) provided with his masterly lid autapomorphy is evidenced by the presence of two
illustrations a very incisive comparative analysis of the instead of three outer setae on the distal endite. The
mandibular evolution in Bathynellacea as a whole and autapomorphies of Leptobathynella are still more spectac-
diagnosed the following features as being most distinctive ularly manifest in the maxilla: 1) the proximal segment is
of Leptobathynellidae: 1) corpus is longer than high; 2) bare whereas it is armed with three setae in C. leleupi; 2)
pars incisiva is localised in the antero-distal region; 3) the mid-inner margin of the second segment, i.e., junction
molar teeth, only three in number, are arranged parallel to between the ancestral segments 2 and 3, has a single seta
the longitudinal axis; 4) adductor muscles are directly vs. three setae; 3) segment(s) 2 (and 3) have nine or ten
implanted on the mandible; 5) general developmental axis setae vs. 14 setae; 4) a single terminal claw vs. two claws;
and connective border parallelly oriented. We may add here and 5) thoracopod II has no epipod vs. with one well-
another character, viz., a shift in the position of the palp developed epipod; setal formula of thoracopods II-VII:
from a level well below the pars molaris to a point opposite 0+0/0+1/0+0/2(1) vs. 0+0/0+1/0+1/2(1); basis of thoraco-
or distal to pars molaris. Overall, the lobe- or plate-like pars pods I-VII as well as the first endopodal segment of
molaris, which is typical of Parabathynellidae, is absent in thoracopod I is unarmed vs. armed with one seta each.
Leptobathynellidae, resulting in the implantation of its From the foregoing discussion, it is clear that Leptobathy-
three teeth (spines/claws) directly on the mandible and nellidae is monophyletic.
parallel to its long axis – the single most important The revalidation of Leptobathynellidae begs an obvious
leptobathynellid autapomorphy. question: does this action not render Parabathynellidae
We now can consider here the phylogenetic relationships paraphyletic? The answer is no. A simple comparison of
amongst the leptobathynellid genera based on the mandib- Parabathynellidae with the most primitive Bathynellidae
ular features. Within the mandibular frame, Acanthobathy- bears this out. The morphologic details (plesiomorphic vs.
nella appears to be most primitive in that the pars incisiva is apomorphic) of the body and all the appendages without
relatively large and, as an exception, the lobe of pars molaris any exception are so obviously and overwhelmingly
still persists but as a small protuberance, bearing the three different between these two families that they seem to hint
teeth, which are represented by small and blunt projections. at the possible existence of a new intermediate taxon.
 RANGA REDDY ET AL.: PARVULOBATHYNELLA FROM INDIA 507

Ecology copepods (Allocyclopina Kiefer, 1954, Haplocyclops Kie-

Parvulobathynella ypacaraiensis inhabits lacustrine sand- fer, 1952, Rybocyclops Dussart, 1982, sioli- and minuta-
banks whereas all other known species of Parvulobathy- groups of the polyphyletic Parastenocaris Kessler, 1913,
nella including the two Indian congeners occur in the and Kinnecaris Jakobi, 1972) exhibit Gondwanan patterns,
interstitial banks of streams or rivers. Neither of the Indian the present record of Parvulobathynella in tropical India is
congeners was present in the samples collected from far hardly surprising. However, Lopretto and Morrone (1998)
inland karstic aquifers such as caves and boreholes. presumed that this genus belonged to ‘‘Northern tropical
Parvulobathynella distincta was collected in two principal track,’’ connecting tropical South America and Africa, with
rivers of the peninsular India, viz., the Godavari and an Atlantic Ocean baseline. What is particularly puzzling at
Krishna. Within these river basins, this species was this juncture is that such genera as Billibathynella Cho,
distributed somewhat widely at different points over a 2005, Notobathynella Schminke, 1973a, and the cosmo-
politan Hexabathynella Schminke, 1972a, have not yet
linear range of 26-135 km from the present coastline of the
turned up in India. Since Parvulobathynella has already
Bay of Bengal. A lone representative of this species
been reported from two locations each of South America
appeared, however, in an agricultural bore-hole, not far
(Paraguay and Chile) and Africa (South Africa and Ivory
from the river bank. On the other hand, P. projectura was
Coast), the present record extends the geographical range
confined to its type locality, which experiences pure
of this genus to South Asia in the northern hemisphere (Fig.
freshwater conditions only during peak monsoon activity
14). Though we have as yet only a very few records of
(August-October) but is subject to the tidal influence from
Parvulobathynella in South America, Africa, and now
the nearby Bay of Bengal at other times (see Defaye and
peninsular India, future investigations are likely to show its
Ranga Reddy, 2008). Both P. distincta and P. projectura
widespread distribution on all Gondwana landmasses
can tolerate the seasonal brackish conditions, but are rather
including Australia and Madagascar.
rare in their occurrence, having appeared in only 17 and 3
Biogeographically, the occurrence of Califobathynella in
samples, respectively, out of over 3000 samples examined
North America is incongruous. As already mentioned, in
so far. Further, both these species were found in very small
terms of morphology, this genus is very close to, and can
numbers on most occasions, with females occurring either
perhaps sink in the synonymy of, Parvulobathynella.
alone or outnumbering males. Having similar body size and
Probably there was some mix-up in Noodt’s collections
nearly identical mouthparts, they were never found in one
on which this genus was erected.
and the same sample. Two species of the same genus can
In conclusion, this is the first record of Parvulobathy-
coexist when they either differ in body size or in the
nella from India and, on a broader geographic scale from
structure of the mouthparts (Schminke, 1973a, b). On
Asia, and fills a significant gap in the geographic range of
several occasions, P. distincta co-occurred with habro-
the genus. The revalidation of Leptobathynellidae does not
bathynellid species, which are relatively large-bodied and
render Parabathynellidae paraphyletic. Further studies
have different mandibular structure (Ranga Reddy and
required to understand the phylogenetic and biogeographic
Totakura, 2010).
relationships of leptobathynellid genera, especially Lepto-
In terms of ecological distribution, both P. distincta and bathynella and Califobathynella.
P. projectura are not different from their counterparts of
Habrobathynella in that they inhabit the same hyporheic
habitats that lie very close to the coast of the Bay of
Bengal. And there is enough evidence to show that several ACKNOWLEDGEMENTS
of the habitat areas of these species were subject to marine We thank the Department of Science and Technology, Ministry of Science
transgression at one time or more times during the and Technology, Government of India, New Delhi, for providing funding
support under a Major Research Project (SR/SO/AS/25/2007), and Prof.
Cenozoic. Further, we have no distribution records of Dr. Schminke and Dr. A. I. Camacho for their valuable comments on the
these taxa in far inland alluvial or karstic freshwater first draft of the manuscript and also for answering our queries or helping
aquifers. And yet, it is still a moot question whether these with the literature. We are also grateful to the anonymous reviewers for
taxa are relicts of a Tethyan fauna (thalassoid: Boutin and their constructive criticism, and Prof. Dr. Frederick R. Schram for his
painstaking edit input.
Coineau, 1990) or their present costal existence is a case of
secondary transition, with the primary roots in freshwater
(limnicoid: Schminke, 1981). Judging the available cladis-
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