Dussartstenocaris bisetosa, Reddy, Yenumula Ranga, Totakura, Venkateswara Rao & Shaik, Shabuddin, 2016

Reddy, Yenumula Ranga, Totakura, Venkateswara Rao & Shaik, Shabuddin, 2016, Two new species of Parastenocarididae (Copepoda, Harpacticoida) from India, Zootaxa 4066 (2), pp. 125-151 : 137-146

Dussartstenocaris bisetosa n. sp.

( Figs. 8–13 )

Type locality. Farm bore (water temperature 32ºC, pH 7.0) at Chintalapudi village, ~ 5 km from Nidubrolu town (16°02′23.8″N, 80°32′35.4″E; elevation ca 36.5 m) in Guntur District, Andhra Pradesh state, southeastern India ( Fig. 1 ).

Type material examined. Holotype male (MNHN-IU-2013-11956) and allotype female (MNHN-IU-2013- 11957), dissected on 4 slides each; 2 paratypes: 1 male (MNHN-IU-2013-11958), dissected on 4 slides; 1 male (MNHN-IU-2013-11959), whole-mounted on 1 slide; 0 4 January 2010, Coll. V. R. Totakura.

Other material examined. 1 male, dissected on 3 slides in TVR’s personal collections. Farm bore at Kunchanapalli village (16º23′42.1″N, 80º32′28.2″E, elevation 26 m; water temperature 28ºC, pH 7.0) in Guntur District, Andhra Pradesh, South India, 21 December 2010, Coll. V. R. Totakura.

Description of adult male. Total body length, measured from tip of rostrum to posterior margin of caudal rami, 296–352 Μm. Preserved specimens colourless. Nauplius eye absent. Habitus ( Fig. 8 A) cylindrical and slender, without any demarcation between prosome and urosome; prosome/urosome ratio about 0.8 in dorsal view; greatest width in dorsal view at genital somite. Body with thin, imperforated cuticle, length/width ratio about 7.4. Free pedigerous somites without any expansions; all somites connected by well developed arthrodial membranes. Hyaline fringes of all somites smooth, narrow and hard to distinguish from arthrodial membranes. Integument ornamented with sensilla, some pores and spinules, and also with somewhat obpyriform cuticular double-window on cephalothorax, somewhat close to posterior margin, and 1 elliptical, dorsal cuticular window each in the anterior half of genital somite and next 3 urosomites; window on genital somite smallest. Cephalothorax ( Fig. 8 a) obovate, about 1.3 times as long as wide in lateral view, representing 16.7% of total body length. Surface of cephalic shield ornamented with 8 pairs of sensilla. Rostrum ( Figs. 8 a, b, 10a) small, membranous, not demarcated at base, ornamented with 2 dorso-lateral sensilla. Second pedigerous somite as wide as posterior half of cephalothorax in dorsal view, with 2 pairs of large sensilla, 1 pair proximally. Third pedigerous somite slightly longer than second pediger, with 2 pairs of large sensilla. Fourth pedigerous somite as long as third prosomite, with 2 pairs of large posterior sensilla.

Urosome ( Fig. 9 a, b) gradually narrowing behind. First urosomite as wide as distal half of genital somite, with 2 pairs of dorso-distal sensilla and 1 pair each on ventral surface of urosomites 1–4. Genital somite shorter than first urosomite, also with 3 pairs of sensilla (dorsal, lateral) and 1 sensillum on either side of sixth legs. Third and fourth urosomites nearly as long as genital somite, with 2 pairs of sensilla (dorsal, lateral). Preanal somite without any surface ornamentation. Anal somite about 1.5 times as long as wide in dorsal view, slightly narrower than preanal somite; ornamented with 2 short rows of small spinules at 2/5 of segment length, 1 complete row of very fine spinules close to posterior margin of anal operculum, 8 mid-dorsal, relatively large spinules, 1 pair of large dorsal sensilla at base of anal operculum and 1 cuticular pore proximo-laterally. A single, large, longitudinally placed spermatophore ( Fig. 8 a) visible through genital somite and next somite, about 2.9 times as long as wide, bean-shaped, with narrow curled neck. Anal operculum moderately developed, with smooth, slightly convex margin, not reaching posterior end of anal somite and representing 74.3% of somite's width. Anal sinus wide, ornamented with 1 short diagonal row of 3–5 spinules on either side postero-ventrally as in Fig. 9 a-d.

Caudal rami ( Fig. 9 a–c): divergent, cylindrical, narrow at base in ventral view; about 4 times as long as greatest width in dorsal view and about 0.7 times as long as anal somite; armed with 6 setae (2 lateral, 1 dorsal, 2 apical, and 1 subapical), and with ventral row of fine spinules along posterior margin, of which 1 spinule at inner distal corner elongate. Lateral setae (I, III) unequal and located slightly anterior to midlength; seta II missing. Dorsal seta (VII) inserted at distal fifth of caudal rami and close to inner margin, slender, plumose, about as long as caudal ramus and biarticulate basally. Inner apical seta (VI) smooth, inserted close to ventral margin, about long as ramus. Middle apical seta (V) stout, without breaking plane, bipinnate, about 6.2 times as long as ramus, pointing distally, with acute tip. Outer apical seta (IV) small, smooth, only about 0.4 times as long as ramus, inserted close to dorsal surface and pointing laterally.

Antennule ( Fig. 10 b): slightly longer than cephalothorax, slender, 8-segmented, ‘coiled type’; digeniculate, geniculation between fourth and fifth, and between sixth and seventh segments. First segment short, ornamented with 1 row of spinules; second segment longest, being about 3 times as long as maximum width; segments 5 and 6 moderately dilated; segment 5 without any proximal spiniform process on anterior surface, with moderately developed aesthetasc, constricted at about midlength, with blunt tip, barely reaching end of ultimate segment, and fused basally with 1 simple seta; ultimate segment with aesthetasc, only slightly smaller than that on segment 5, fused basally with 2 setae (acrotheck). Setal formula: 0.5.4.1.4+aes.0.0.9+aes. All setae slender, smooth; proximalmost seta on second segment unipinnate with long setules along disto-lateral margin; proximalmost seta of segments 2 and 8 articulate basally. Length ratios of segments, from proximal to distal end and along caudal margin 1.0:2.6:0.7:0.4:2.5:1.1:1.7:1.5.

Antenna ( Fig. 10 c): composed of coxa, allobasis, 1-segmented endopod, and 1-segmented exopod. Coxa very short, ornamented with arched row of short spinules. Allobasis about 3.8 times as long as maximum width and ornamented with 2 arched rows of spinules on anterior surface. Exopod small, somewhat cylindrical, about 3.3 times as long as wide, unornamented, armed with 1 apical seta, which is 3.3 times as long as segment. Endopod 0.6 times as long as allobasis and about 2.3 times as long as wide, with surface frill distally, ornamented with 2 spinular rows on inner margin and armed laterally with 2 short bipinnate unequal spines and apically with 5 strong elements (2 subequal spines, 2 subequal geniculate setae and 1 unipinnate transformed seta).

Mandible ( Fig. 10 d): cutting edge narrow on elongate coxa and with 2 complex teeth ventrally, 1 unipinnate seta dorsally, and several smaller teeth. Palp 1-segmented, cylindrical, about 3.2 times as long as wide, unornamented and armed apically with 2 smooth apical setae.

Maxillule ( Fig. 10 e): praecoxal arthrite rectangular, about 2.2 times as long as wide in lateral view, armed with strong lateral seta and 3 weak apical elements. Coxal endite armed with 1 smooth apical seta. Basis; (c) genital field. slightly longer than coxal endite and armed with 2 smooth apical setae.

Maxilla ( Fig. 10 f): composed of syncoxa, basis and 1-segmented endopod. Syncoxa with 2 endites, proximal one short and armed with 2 smooth apical setae, and distal endite armed with 1 smooth seta and 1 strong pinnate spiniform seta apically. Allobasis prolonged into strong unipinnate claw and without seta at base. Endopod represented by small segment, armed with 2 smooth apical setae.

Maxilliped ( Fig. 10 g): syncoxa unarmed and unornamented; basis slender, 5.5 times as long as wide; endopod small with unipinnate claw, about 0.6 times as long as basis.

Legs 1–4 ( Fig. 11 a–c, g): praecoxa and intercoxal sclerite of all legs smooth.

Leg 1 ( Fig. 11 a): coxa rhomboidal, ornamented with 1 row of small spinules disto-medially. Basis shorter than coxa, trapezoidal, with outer seta and ornamented with 1 row of spinules each near base of exopod and endopod. Exopod 3-segmented; first segment 0.8 times as long as next 2 segments combined; segments 1 and 2 with 1 longitudinal row of spinules each at outer distal corner, and segment 3 with 1 longitudinal row of spinules at about midlength of inner margin; segment 1 armed with 1 short and slender outer bipinnate spine; segment 2 unarmed and segment 3 with 4 elements (1 outer spine, 1 apical seta and 2 apical geniculate setae). Endopod 2-segmented, slightly longer than exopod; first segment 1.6 times as long as second exopodal segment, 3.1 times as long as wide, unarmed and ornamented with 2 rows of elongate spinules on outer margin and 2 longitudinal rows of small spinules on inner margin; segment 2 ornamented with 1 row of spinules on inner margin and armed with 1 spine subapically and 1 long geniculate seta apically; endopodal geniculate seta 1.4 times as long as entire endopod, almost twice as long as outer spine on endopod, 1.2 times as long as inner geniculate seta on exopod. All exopodal and endopodal armature elements except spine on first exopodal segment unipinnate along outer margin.

Leg 2 ( Fig. 11 b): coxa with 1 arched row of spinules near inner distal corner. Basis smaller than coxa, unarmed and ornamented with 1 row of spinules along outer margin and 1 row of fine spinules at base of endopod. Exopod 3-segmented; ornamented with isolated rows of spinules along outer margins of all segments; segments 1 and 3 with hyaline frill each at inner distal corner, but segment 2 with 1 row of spinules instead. Segment 1 strong, 1.3 times as long as next 2 segments combined, armed with 1 outer spine on segment 1; segment 2 unarmed; segment 3 about as long as segment 2, armed with 3 elements (1 subapical spine and 2 apical plumose setae); innermost seta 1.4 times as long as exopod. Endopod 1-segmented, slender, almost cylindrical, 7.6 times as long as wide, about 0.6 times as long as first exopodal segment, ornamented with 2 large spinules on subdistal outer margin, and apical margin with 2 spinules and armed with 1 smooth seta, which is 1.2 times as long as endopod.

Leg 3 ( Fig. 11 c–f): coxa trapezoidal, smaller than basis, ornamented with 1 arched row of spinules at inner distal corner. Basis robust, produced at inner distal corner, ornamented with 1 longitudinal row of spinules on inner margin and 1 pore on anterior surface and armed with long, slender, simple seta on outer margin. Endopod represented by very small, rudimentary seta, inserted at distal fourth of inner margin of basis. Exopod with both segments perfectly fused together; ancestral proximal segment moderately strong, slightly curved inwards, 4 times as long as wide, ornamented with 2 rows of spinules on outer proximal margin; ancestral distal segment (apophysis) ladle-shaped, with hyaline lateral margins, unornamented and unarmed; thumb, longer than apophysis, and with 3 unequal apical lobes lined with hyaline margins (arrowed in Fig. 11 c).

Leg 4 ( Fig. 11 g): coxa rhomboidal, ornamented with arched row of spinules at outer distal corner and 2 modified, elongate spinules, reaching almost distal end of basis and with a hyaline zone around them at inner distal corner. Basis trapezoidal and slightly longer than coxa, ornamented with 1 row of small spinules at base of exopod and armed with moderately long seta on outer margin. Exopod 3-segmented, ornamented with rows of spinules on outer margins of all segments and additional row of spinules along inner distal corner of segment 2, 1 hyaline frill each at inner distal corner of segments 1 and 3; segment 1 slightly curved inwards, 0.7 times as long as next 2 segments combined, armed with strong bipinnate outer spine subdistally; segment 2 with straight inner margin and unarmed; segment 3 slightly longer than second one and armed with 1 outer spine and 1 apical bipinnate seta; apical seta 2.2 times as long as outer spine, 3.9 times as long as third exopodal segment, 1.2 times as long as entire exopod. Endopod claw-like and outcurved and ornamented with 1 spinule at proximal third of its length; 2 equal, large spinules also occurring near the base of endopod on outer side with hyaline zone around them.

Leg 5 ( Fig. 9 a, b, e): without intercoxal sclerite; legs distinct at base, small, bowl-shaped plate, located at distal half of somite, with acute, minute spinous process at inner distal angle and smooth inner margins; cuticular pore not discernible; armed with 2 unequal smooth setae on distal margin (probably ancestral endopodal armature), inner seta 2.6 times as long as outer one; basal seta missing.

Leg 6 ( Fig. 9 a, b): smooth, unarmed and unornamented, forming simple operculum covering gonopore, fused with sixth pedigerous somite, hook-like in lateral view, triangular plate-like structure in ventral view.

Description of adult female. Body length, measured as in male, 348 Μm. Habitus ( Fig. 8 b): ornamentation of prosomites, colour and nauplius eye similar to male, except genital somite and first abdominal somite fused into double-somite.

Genital double-somite ( Fig. 12 a): genital complex located mostly in the anteroventral half of genital doublesomite, and broader than high; genital apertures covered by vestigial sixth legs; median copulatory pores also covered by fused sixth legs; seminal receptacles small; copulatory duct very short and sclerotized. All posterior sensilla of third urosomite homologous to those on male, while 2 sensilla from male second urosomite missing. Third, preanal and anal somites very similar to male.

Caudal rami ( Fig. 12 a–c): slightly divergent, 1.5 times as long as anal somite, about 2.8 times as long as wide in ventral view, gradually tapering; armature and ornamentation as in male.

Antennule ( Fig. 10 h): 7-segmented; segment 1 short, ornamented with 1 row of spinules on ventral surface; segment 2 longest; segment 4 with short, moderately strong, medially constricted aesthetasc with pointed tip, slightly overreaching distal margin of sixth segment; aesthetasc on segment 7 more slender and shorter than that on segment 4, 0.7 times as long as segment, fused basally to 2 apical setae (acrotheck); setal formula: 0.4.4.2+aes.1.1.9+aes. All setae, except unipinnate proximalmost one on second segment smooth. Length ratios of segments, from proximal to distal end and along caudal margin 1.0:3.0:1.6:1.3:1.2:0.8:1.4.

Antenna, labrum, mandible, maxillule, maxilla, maxilliped, and leg 1 ( Fig. 13 a) and 5 ( Fig. 12 a) similar to male.

Leg 2 ( Fig. 13 b): coxa rhomboidal, ornamented with 2 rows of spinules on medial surface; basis smaller than coxa; ornamentation same as in male. Exopod similar to male. Endopod nearly cylindrical, 0.7 times as long as first exopodal segment and ornamented with 2 spinules on subdistal outer margin; apical margin armed with 1 seta, which is 0.8 times as long as endopod, and ornamented with 2 spines.

Leg 3 ( Fig. 13 c): coxa with 1 arched row of spinules medially. Basis trapezoidal, ornamented with 4 or 5 large spinules in a row on outer distal margin and armed with long, basally articulate, smooth outer seta, which is 0.8 times as long as entire exopod. Exopod 2-segmented, with large spinules along outer margin, both segments with hyaline frill each at inner distal corner; segment 1 armed with 1 outer spine; segment 2 with outer spine and strong apical seta; seta 3.2 times as long as spine; all armature elements bipinnate. Endopod greatly reduced to small, smooth, knob-like structure (arrowed in Fig. 13 c).

Leg 4 ( Fig. 13 d): exopod similar to male. Endopod 1-segmented, 0.8 times as long as first exopodal segment, straight, ornamented with transverse row of 5 spinules at 3/5 of length, spiniform, ending in acuminate point, and with spinulose disto-lateral margins.

Leg 6 not discernible.

Variation. Number of spinules on ventro-distal margin of anal somite varying between 3 and 5 in male ( Fig. 3 c, d).

Etymology. The specific epithet, bisetosa , from the Latin adjective, setosu s, alludes to the presence two setae on leg 5 in both sexes; gender feminine.

Distribution and ecology. The new species is known only from two farm bores, about 50 km apart, in Guntur District, Andhra Pradesh state. It was accompanied by one bathynellacean species only at the type locality (Chintalapudi bore), and one bathynellacean, one cyclopoid species, a new species of a new parastenocaridid genus, and some other unidentified harpacticoids in the other bore.

Figures

FIGURE 1. Map showing the distribution of Parastenocaris enckelli n. sp. (■) and Dussartstenocaris bisetosa n. sp. (▲).

FIGURE 3. Parastenocaris enckelli n. sp., holotype male: (a) urosome, ventral view; (b) same, dorsal view.

FIGURE 8. Dussartstenocaris bisetosa n. sp., (a) paratype male, habitus, dorsal view; (b) paratype female, habitus, lateral view.

FIGURE 9. Dussartstenocaris bisetosa n. sp., holotype male (a – c); paratype male (d, e): (a) urosome, lateral view; (b) same, ventral view (arrow pointing to large setiform spinule); (c) anal somite and caudal rami, dorsal view; (d) postero-ventral part of anal somite (to show large spinules); (e) fifth legs, ventral view (arrow pointing to lack of basal seta).

FIGURE 10. Dussartstenocaris bisetosa n. sp., holotype male (a – g); allotype female (h): (a) rostrum, ventral view; (b) antennule, dorsal view; (c) antenna, lateral view; (d) mandible, lateral view; (e) maxillule, posterior view; (f) maxilla, lateral view; (g) maxilliped, anterior view; (h) antennule, dorsal view.

FIGURE 11. Dussartstenocaris bisetosa n. sp., holotype male (a – c, g); paratype male (d – f): (a) leg 1, anterior view; (b) leg 2, anterior view; (c) leg 3, anterior view (arrow pointing to trilobed thumb); (d) exopod of leg 3; (e, f) apophysis and thumb; (g) leg 4, posterior view.

FIGURE 12. Dussartstenocaris bisetosa n. sp., allotype female: (a) urosome, ventral view; (b) same, dorsal view; (c) anal somite, lateral view.

FIGURE 13. Dussartstenocaris bisetosa n. sp., allotype female: (a) leg 1, posterior view; (b) leg 2, anterior view; (c) leg 3 anterior (arrow pointing to characteristic endopod); (d) leg 4, anterior view.