The cenotes of Yucatan; a zoological and hydrographic survey, by
A. S. Pearse ... Edwin P. Creaser ... F. G. Hall ... and the following
collaborators: J. Bequaert, H. B. Hungerford ... [and others]
Pearse, A. S. (Arthur Sperry), 1877-1956.
[Washington] Carnegie institution of Washington, 1936.
https://hdl.handle.net/2027/mdp.39015013434280
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XII
HYDRACARINA FROM YUCATAN
By Ruth Marshall
Rockford College
The material, the first to be described from Yucatan, consisted of twenty-two
vials containing small collections made in the summer of 1932; in these there were
seventy-three individuals, most of them in good condition. They were found to
represent eight genera; six species were identified with certainty, of which three
are new. Only a few of the larvae present could be fully identified, while the
Arrhenuri, represented by females only, were not assigned to any species.
Hydrachna sp.
Of the eight individuals of the genus which were found, only one was an adult, a
male not sufficiently well preserved to be identified. The other individuals were unidenti
fied nymphs. Localities: From Belostoma boscii (L. & S.) ; Chotch Cenote, June 21,
5 nymph cases; Halal Aguada, July 28, 1 male, 1 nymph; Pool E, Progreso, August 3,
1 nymph.
Diplodontus despiciens (Mull.)
This common and cosmopolitan species was represented by seven individuals found
in two collections: Xtoloc Cenote, June 7, 3; Balam Canche Cave, June 28, 4.
Limncsia paucisnica Wol.
The species only from the upper Mississippi region. In
has been known heretofore
this material fourteen individuals, males, females and nymphs, were present in eight of
the collections: Balam Canche Cave, June 28, 1 female; Geiser Cenote, July 19, 2 fe
males, I nymph; Niagra Cenote, July 21, 1 female; Olivut Cenote, July 23, 1 female;
Manzanilla Cenote, July 23, 1 female; Carlos Morales, Escuela Cenote, July 28, 1 male;
Halal Aguada, July 28, 2 nymphs; Santa Elena Cave, July 31, 1 male, 2 females, 1
nymph.
Neumania cenotea n. sp.
Figs. 6 to 8
The body oval; males measure 0.80 mm. in length, females, about 0.90
is broadly
mm. The skin In preservation the plates are magenta tinged and the
is finely reticulate.
dorsal side shows a Y-shaped figure. The epimeral groups are well separated; the fourth
pair is considerably wider than the third. Underlying braces from the first groups reach
posteriorly to the center of the fourth pair. The genital areas are relatively small; the
plate on either side of the cleft carries some twenty-five to thirty scattered acetabula of
various sizes. Hairs are numerous on the genital region and on the epimera. The
palpi are distinguished by the large papillas on the fourth segment and by long hairs on
the distal end of the third. The legs diminish regularly in width from the first to the
fourth; the fourth is weak and bears a few pectinate spines and several long hairs on
segments three, four and five.
113
134 THE CENOTES OF YUCATAN
The new is related to N. triangularis
species (Piers.), widely distributed over
It
however, smaller and differs from the size and position of the pa
is,
in
Europe.
it
pillae on the palpi, the greater size of the epimera and details of the genital area.
in
in
Nineteen individuals were found three of the collections; both sexes and one
in
nymph were present: Xanaba Cenote Grande (2), June 26, male; Santa Ana Cenote,
1
Valladolid, July 2, males, females, nymph, poor preservation; Country Club
2
6
7
Cenote, Merida, July 19, male, female.
1
Koenikca indistincta n. sp.
Figs. to
5
This small species, the male measuring 0.425 mm., the female 0.475 mm. The
is
a
body nearly circular outline, with the anterior margin bulging and bearing two
in
is
protuberances on either side the eye region. Hair papillae are numerous. The epimeral
in
groups are well separated, their outlines fairly clear and their surfaces covered with small
pores. The posterior ends of the anterior pair are faint, with indistinct long underlying
processes extending from the first pair. The genital regions are very narrow and faintly
outlined; their acetabula are small, very irregular as to size and position, and scarcely
distinguishable from the larger pores of the general body surface. The palpi end
in
four finger-like processes; the second segment stout, and with the third bears long stout
is
hairs. The legs all exceed the body length and end double sickle-shaped claws.
in
in
Long heavy bristles set sockets are borne by the first pair; smaller ones are found on
in
the others, while few swimming hairs are found on the last two pairs of legs.
a
Three individuals of this new species, one male and two females, were found
in
a
collection from Scan Yui Cenote, June 17.
Piona pearsei n. sp.
Figs. to 14
9
The body elliptical, about 0.90 mm. long the male, 1.15 mm. long and 0.95 mm.
in
is
broad the largest female. The epimeral groups are close together; the fourth plate
in
of each side much the largest, not entirely separated from the third and has conspicuous
is
posterior corners. In the male the third and fourth epimera of either side are nearly
touching the midline. The genital areas are small, with few and irregularly scattered
in
acetabula; the clefts are long and close to the last epimera. The genital plates the male
in
are wing-shaped, somewhat truncated at the outer ends, and each bears nine acetabula
in
the specimens examined, one of which more anterior than the others. In the female
is
the number of acetabula about eleven on each side; they are set on small plates the
in
is
body wall, arranged sickle-shaped formation. The most anterior acetabulum of each
in
side somewhat separated from the others and has larger plate, the latter bearing
is
also four or five hair attachments. The acetabula of the two sides may vary little in
a
their arrangement. The palpi are stout, with stout bristles; the fourth segment has
a
conspicuous conical papilla on the inner side midway of its length. The legs, except the
third the male, end large bifid claws, the segments narrowed proximally. In the
in
in
male the last segment of the third leg very short and bears one long slender claw and
is
one short curved one; the fourth segment of the last leg has small concavity on the sides
a
of which grow few stout bristles and short dagger-like hairs. The new species re
a
sembles P. braziliensis Viets, especially the female, but differs from conspicuously
in
it
the form of the male genital area.
Specimens were found at Valladolid, Santa Ana Cenote, July 2; two males and
twelve females. The species name given recognition of Dr. A. Pearse who made
in
S.
is
HYDRACARINA FROM YUCATAN 135
the collections and kindly allowed the author to examine the material. One unidentified
larva of this genus was found at Xanaba Cenote Grande (2), June 27.
Mideopsis orbicularis (Mull.)
Three specimens of this widely distributed species were found: Piste Cenote, July
1 8, 1 ; Yuncu Cenote, July 23, 1 adult, 1 nymph.
Arrhenurns sp.
Figs. 15 to 17
The body of the female is broadly ovate, 0.975 mm- long, an^ deep blue-green in
preservation. The dorsal enclosed area is large. The anterior body outline between
the eyes is slightly concave. The epimera are well defined. The first pair is
distinctive; here the posterior ends are triangular, leaving a deep inverted V-shaped bay be
tween them. The fourth epimera are rather narrow, with conspicuously rounded inner
posterior borders. The genital plates are large; the wing-shaped areas are broad, with
anterior borders faint. The palpi show a large patch of coarse curved hairs on the
bulging second joint.
Six individuals were found: Zanaba Cenote Grande (2) ; June 27. A specific name
is withheld until the male is recognized. One unidentified larva of this genus was found
in the collection from Scan Yui Cenote; June 16.
T H E C E NOT E S OF YU CAT AN
s
FIG. 1–Koenikea indistincta, right palpus.
FIG. 2–Koenikea indistincta, genital area, male.
FIG. 3–Koenikea indistincta, region of right eye.
FIG. 4–Koenikea indistincta, dorsal view, male.
Fig. 5–Koenikea indistincta, ventral view, female.
FIG. 6–Neumania cenotea, ventral view, male.
FIG. 7–Neumania cenotea, genital area, female.
FIG. 8–Neumania cenotea, right palpus, female.
HYDRA CA R IN A FROM YU CAT AN 137
FIG. 9—Piona pearsei, ventral view, male.
FIG. Io-Piona pearsei, end of leg II (one claw omitted).
FIG. 11—Piona pearsei, end of leg III, right, male.
FIG. 12—Piona pearsei, left palpus, female.
FIG. 13—Piona pearsei, 4th and 5th segments, leg IV, male.
FIG. 14—Piona pearsei, genital area, female.
FIG. 15—Arrhenurus sp., dorsal view, female.
FIG. 16—Arrhenurus sp., ventral plates, female.
FIG. 17—Arrhenurus sp., right palpus.
