Rybocyclops dussarti Reddy & Defaye, 2008, sp. nov.
Creators: name: Reddy, Yenumula Ranga
name: Defaye, Danielle
Publisher: name: Zenodo
Year: 2008
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Cyclopoida
Cyclopidae
Rybocyclops
Rybocyclops dussarti

description: Rybocyclops dussarti sp. nov.
(Figs 1–3)
Material examined. Holotype, adult female, dissected on one slide (MNHN-Cp2360); allotype, adult male, dissected on one slide (MNHN-Cp2361); paratypes, dissected on one slide each; 8 females (MNHN-Cp2362 to MNHN-Cp2368, MNHN-Cp2370) and 5 males (MNHN-Cp2369, MNHN-Cp2371 to MNHN-Cp2374); all from Chollaveedu village, 14 January 2006, leg. Y. Ranga Reddy, India, Andhra Pradesh, a roadside agricultural bore-well, about one km from Chollaveedu village, 15° 31'39" N, 78° 56' 56" E, elevation 231 m, on the way to Turimella via Akkapalli, in Racharla Mandal of Prakasam District.
Two males MNHN-Cp2375 and (MNHN-Cp2391), dissected on one slide each, two females and three males (MNHN-Cp 2376), preserved in 70% ethanol, from Araveetikota. 10 April 2006, leg. Y. Ranga Reddy, India, Andhra Pradesh, village bore-well at Araveetikota, 15° 34' 49" N, 78° 55' 56" E, elevation 235 m, about 7 km from the type locality. All this material has been deposited in the National Museum of Natural History, Paris.
Etymology. The new species is named in honour of Dr. Bernard H. Dussart, an eminent copepodologist and a chief contributor to our knowledge of the copepod fauna of Madagascar. The name is a noun in the genitive singular.
Diagnosis. Small cyclopoids, mostly less than 400 µm in length, with smooth integument. Genital doublesomite 0.7 as long as wide and as long as next three urosomites combined. Seminal receptacle consisting of anterior and posterior parts, anterior part slightly larger, with both external edges rounded; copulatory pore lying in median ventral position. Anal somite with moderately large operculum. Caudal rami characteristic in shape, about twice as long as wide, parallel, with lateral seta inserted in distal half dorsally and principal seta outcurved proximally and without breaking plane. Female antennule 11-segmented, with three setae on seventh segment. Male antennule 16-segmented. Antenna 4-segmented, with setal formula 1.1.6.7 and without seta representing exopod. Mandibular palp lacking. Maxillulary palp, with distinct endopod bearing one inner and two apical setae. Maxilliped 5-segmented, with 0, 2, 1, 1 and 2 setae. Legs 1–4 with 2-segmented rami. Legs 1 and 4 without coxal seta. Spine formula of second exopodal segment 2.2.2.2. and setal formula 5.5.5.4. Second endopodal segment of leg 4 in male with one seta more than in female. Leg 5 completely fused to somite, represented by three slender setae. Leg 6 a distinct cuticular plate, armed with two setae in both sexes.
Description of the female holotype. Total body length, measured from base of rostrum to posterior margin of caudal rami (excluding caudal setae) 416 µm (paratypes 485–520 µm, n = 3). Preserved specimens colourless. Naupliar eye absent. Body (Fig. 1 a) somewhat robust, dorsoventrally compressed, with prosome/ urosome ratio 1.7 and greatest width (139 µm) at posterior end of cephalothorax. Body length/width ratio 2.8. Cephalothorax 1.9 times as wide as genital double-somite, not produced posterolaterally. Rostral projection (Fig. 1 c) moderately developed, broadly triangular in ventral view. Free pedigerous somites with unproduced, rounded posterolateral corners. Pseudosomite present between prosome and urosome, but discernible more clearly in ventral view. Fifth pedigerous somite 0.9 as wide as genital double-somite and with rounded lateral margins.
Cephalothorax (Fig. 1 a) 1.2 times as long as its greatest width and 42.9% of total body length. Hyaline fringes of prosomites narrow and smooth. Fifth pedigerous somite with smooth fringe dorsally and ventrally. Sensilla not discernible under the optics used.
Genital double-somite (Fig. 1 a, b) 0.7 as long as wide. Hyaline fringe of genital double-somite and next two somites smooth on either surface. Seminal receptacle composed of anterior and posterior parts, anterior part slightly larger, with both external margins rounded; a small internal cuticular thickening visible; copulatory duct short and straight.
Anal somite (Fig. 1 a, d) ornamented with transverse row of spinules on ventral posterior margin (not illustrated). Anal operculum smooth, broad, 79% of somite’s width, overreaching posterior margin of somite, with slightly depressed mid-posterior margin. Anal sinus without apparent ornamentation.
Caudal rami (Fig. 1 d) symmetrical, appearing parallel and close to each other and 36% longer than anal somite; each ramus twice as long as maximum width, with outer edge slightly concave and inner edge slightly convex, and with a row of tiny spinules at base; similar spinules also occurring at base of outermost apical setae and at distal inner corners. Dorsal seta longer than outer median seta, inserted at 4/5 of ramus length and uniarticulate at base. Lateral seta arising from dorsal surface close to outer margin at 3/5 of ramus length and about as long as maximum width of ramus. Outermost apical seta spiniform, 0.7 as long as ramus, inserted subterminally. Innermost apical seta slenderer and shorter than outermost apical seta. Outer median apical seta proximally outcurved, without breaking plane, 4.7 times as long as outer seta and nearly half as long as whole body. Inner median terminal seta 1.7 times as long as caudal ramus. All furcal setae plumose.
Antennule (Fig. 1 e) 11-segmented, extending up to 5/4 of cephalothorax in length, unornamented, segment 8 with incomplete septum. Setal formula: 6, 3, 4, 1, 1, 1, 3, 1, 2, 2, and 7 (segmental homologies: I-V, VI-VII, VIII-XI, XII-XIII, XIV, XV-XVI, XVII-XX, XXI-XXIII, XXIV, XXV, XXVI-XXVIII). Length ratio of antennular segments along median axis: 1.0: 0.3: 0.5: 0.2: 0.1: 0.3: 0.6: 0.6: 0.4: 0.5: 0.6.
Antenna (Fig. 1 f) 4-segmented, consisting of coxobasis and 3-segmented endopod. Setal formula of endopod: 1, 6, and 7 (setae on second endopodal segment appearing on fig.1f as all terminal, due to mounting distortion; two of these setae actually inserted on the internal distal quarter of the antenna). Coxobasis twice as long as wide, unornamented and with one robust seta at distal inner corner; exopodal seta absent. First endopodal segment 1.2 times as long as wide, ornamented with a row of long spinules at distal outer corner and armed with one seta at about midlength of inner margin. Second segment 1.6 times as long as maximum width, ornamented with a row of spinules at distal outer corner and armed with six unequal setae at distal inner corner. Third segment 2.2 times as long as wide, ornamented with tiny spinules on distal half of outer margin and armed with seven unequal setae, one of them particularly long.
Labrum (Fig. 2 a) trapezoidal, no ornamentation discernible. Anterior edge almost straight, with 18 acute teeth (middle teeth relatively small) between slightly produced rounded lateral corners.
Mandible (Fig. 2 b): coxal gnathobase with 11 teeth and a long external bipinnate spine. No palp observed.
Maxillule (Fig. 2 c): praecoxa shorter but stouter than palp. Arthrite of praecoxa with four apical spines, one of them strong, claw-like; innermost one distinct and pinnate; third one (from inner side) also distinct but naked. Praecoxa armed with six small claw-like spines on inner side. Palp with distinct endopod bearing one inner and two apical setae, one exopodal seta, and armed apically with two slender, smooth setae and one stout, bipinnate spine.
Maxilla (Fig. 2 d): praecoxa fused to coxa on posterior surface and with well-developed proximal endite, bearing two plumose setae; distal endite small, unarmed. Proximal endite of coxa with one short, bipinnate seta; distal endite highly mobile, elongate and armed apically with two unequal setae, proximal seta longer. Basis expanded with robust unipinnate claw, carrying two very unequal setae; stouter seta bipinnate and slightly longer than claw. Endopod two-segmented; proximal segment armed with one stout, bipinnate seta and one weak, smooth seta. Distal segment small and armed with one strong bipinnate seta and two small, smooth setae.
Maxilliped (Fig. 2 e) apparently five-segmented, with two-segmented endopod. Syncoxa showing a widerthan-long, unarmed and unornamented part and a second, longer-than-wide, armed part with two pinnate setae at distal inner margin and ornamented with a row of fine spinules on distal outer margin (not figured). Basis somewhat dilated distally, armed with a single pinnate seta (or two?) at distal inner corner, and ornamented with a row of spinules near base of seta and on distal outer margin. First endopodal segment small and armed with one seta, and second segment with two long pinnate setae (ornamentation not figured).
Legs 1–4 (Figs 2 f–i) relatively short, with two-segmented exo- and endopods. Hairs present on inner margin of basis, lateral margins of second exo- and endopodal segments and outer margin of both endopodal segments of all legs. Endopod nearly equal in length to exopod on legs 1–3, but distinctly shorter on leg 4. Spine and setal formula as follows:
Second exopodal spine formula: 2.2.2.2. Second exopodal setal formula: 5.5.5.4. Intercoxal plates with rounded small prominences, and no ornamentation on all legs. Outer seta on basis of leg 1 very long and plumose distally; same seta on legs 2–4 short and plumose. Coxa without seta on legs 1 and 4, but with short plumose seta on legs 2 and 3.
Leg 5 (Fig. 2 j) completely fused to somite and represented by three slender setae. Remnant of basal segment represented by barely visible elevation, with outer basal seta; two other setae representing ancestral distal segment, slightly unequal and shorter than basal seta.
Leg 6 (Fig. 2 k) located laterally on genital double-somite on a small hump, composed of a small rounded plate bearing two tiny conical processes.
Description of the male allotype. Total body length excluding caudal setae 325 µm (paratypes 415, 500 µm). Habitus (Fig. 3 a) slenderer than, and somewhat different in shape, from female. Prosome/urosome ratio 1.25, greatest width at about midlength of cephalothorax. Body length/width ratio 3.4. Rostral expansion well developed (Fig. 3 b, e). Cephalothorax 1.8 times as wide as genital somite and representing 35.7% of total body length; anterior one-fifth narrow; posterolateral corners not produced. Free pedigerous somites somewhat produced at posterolateral corners. Hyaline fringes of all somites narrow and smooth. Fifth pedigerous somite expanded at midlength and almost as wide as genital somite. Genital somite slightly wider than long. Third, fourth and fifth urosomites unornamented. Anal somite similar to female, anal operculum not extending beyond posterior margin of somite.
Caudal rami (Fig. 3 c) similar to female, 32% longer than anal somite; each ramus 1.7 times as long as maximum width. Armature and ornamentation almost as in female.
Antennule (Fig. 3 e) digeniculate, 16-segmented. Segments 1 and 16 with one slender aesthetasc each. Setal formula: 7, 3, 2, 0, 1, 0, 0, 0, 0, 3, 0, 1, 0, 2, 1, and 6.
Other cephalic appendages and legs 1, 2, 3 and 5 as in female.
Leg 4 (Fig. 3 f): second endopodal segment with one additional seta on inner margin; otherwise as in female.
Leg 6 (Fig. 3 d): both legs partly fused medially; each leg large, cuticular plate-like, armed with two unequal setae.
description: Published as part of Reddy, Yenumula Ranga & Defaye, Danielle, 2008, Discovery of the genus Rybocyclops Dussart, 1982 (Crustacea, Copepoda, Cyclopoida) in subterranean groundwaters of southeastern India, with the description of a new species and its biogeographic significance, pp. 40-50 in Zootaxa 1810 on pages 41-47, DOI: 10.5281/zenodo.182774