Habrobathynella pseudoindica, Totakura, Venkateswara Rao & Reddy, Yenumula Ranga, 2014

Totakura, Venkateswara Rao & Reddy, Yenumula Ranga, 2014, Three new species of the genus Habrobathynella Schminke, 1973 (Syncarida, Parabathynellidae) from the peninsular India, Zootaxa 3826 (1), pp. 139-168 : 157-165

Habrobathynella pseudoindica n. sp.

( Figs 16–22 )

Type locality. River Krishna (water temperature 27°C; pH 7.5) at Chamarti village (16°34'56.0"N, 80°16'31.7"E; elevation 35 m) in Guntur District, Andhra Pradesh, South India ( Fig. 1 ).

Type material examined. Holotype ♀ (MNHN-IU-2013-11844), dissected on 3 slides and allotype ♂ (MNHN-IU-2013-11845), dissected on 4 slides and 3 paratypes: 1 ♀, dissected on 3 slides (MNHN-IU-2013- 11846); 1 ♂, dissected on 3 slides, and 1 ♂ whole-mounted on 1 slide (MNHN-IU-2013-11847); also, 1 ♂ juvenile, dissected on 4 slides, in senior author’s collections; 30 June 2008, Coll. V. R. Totakura.

Diagnosis. Male Th VIII relatively short, subglobular; dentate and inner lobes only moderately produced, dentate lobe with 3 transverse rows of denticles distally; outer lobe smooth, fused with protopod; uropodal sympod with inhomonomous row of 4 spines, of which the ultimate spine distinctly larger than the others, which are similar in size; setae on uropodal endopod about as long as spur; pleotelson slightly protruded in lateral view; maxilla with 2 distinctly unequal setae on first segment; second segment armed at inner distal corner with claw-like seta, which is 43% of apical claw in length. Labrum vaulted, with 10 main, large teeth; first endopodal segment of Th I unarmed.

Description of adult male. Total body length 0.96 mm; paratypes 0.91–0.97 mm. Body ( Fig. 16 ) elongate, heavily chitinised and perforated, 10.2 times as long as wide, and thoracomeres and pleomeres telescoping into each other to varying degrees. In lateral view, pleomeres wider than thoracomeres. Head 1.2 times as long as wide, 23.3% longer than first 2 thoracomeres combined.

Antennule ( Figs 16 , 17 a): 6-segmented; no sexual dimorphism, measuring 21.1% as long as head. First segment with 1 plumose seta on small protuberance on outer margin, 2 plumose setae and 1 long simple seta on dorsal surface subdistally, and 1 small ventral plumose seta near inner margin subdistally. Second segment with 3 plumose setae in a row on dorsal surface, 1 ventral plumose seta on protuberance near outer margin, and 1 ventral seta on inner distal margin. Third segment with 1 long simple seta and 1 plumose seta at inner distal corner, and 1 ventral simple seta subdistally. Inner flagellum subquadrate, bearing 3 unequal simple setae. Fourth segment with stout apophysis, overreaching midlength of next segment and with 2 unequal plumose setae; 1 plumose seta on small protuberance and 1 stub seta on distal margin. Fifth segment with 3 unequal aesthetascs, somewhat overreaching sixth segment, 1 subapical seta at outer distal corner, 2 simple setae on distal margin, and 1 short modified seta at inner distal corner. Sixth segment with 3 unequal, slightly subeaqual aesthetascs and 4 unequal setae.

Antenna ( Fig. 17 b): 2-segmented, proximal segment bare, 0.6 times as long as distal segment; second segment 1.6 times as long as wide, with 1 small outer proximal seta, 2 strikingly unequal terminal setae, of which inner seta plumose and 1.6 times as long as segment, and 1 reduced subterminal dorsal seta.

Labrum ( Fig. 17 c): dentate margin moderately vaulted on either side, bearing 10 main, large, nearly uniform, pointed, curved teeth and 1 small tooth on either side. Also, 4 rows of fine spinules (ctenidia) and 2 teats on ventral surface, as illustrated.

Mandible ( Figs 17 d–e): distal part of pars incisiva with 4 unequal teeth. Tooth of ventral edge large, articulate, and with smooth lateral margins. Pars molaris developed into pyriform outgrowth, 1.4 times as long as wide, carrying 2 curved smooth lateral teeth and 3 straight slender, serrulate teeth in a group at distal end and 1 small tooth at disto-outer corner. Palp completely absent.

Paragnaths: not studied.

Maxillule ( Fig. 18 a): with 2 endites; proximal endite small, subquadrate, carrying 4 unequal claws on distal margin, one of which very small. Distal endite subcylindrical, about 3 times as long as wide, and armed with 2 apical claws, distalmost one larger, bent inwards, 4 unequal claws on inner margin and 3 subterminal setae on outer distal margin.

Maxilla ( Fig. 18 b): 2-segmented; basal segment twice as long as wide, with 2 distinctly unequal setae at inner distal, rounded corner. Second segment 2.2 times as long as basal segment and armed with 15 setae including 2 setae at midlength of inner margin. Third segment completely fused with terminal falcate claw, which has finely serrulate inner distal margin.

Th I–VII ( Figs 19 a–d, 20a–c): as in H. ajraoi n. sp.

Th VIII ( Fig. 21 a–e): subglobular in lateral view; protopod well developed. Outer lobe small, fused with protopod. Both dentate and inner lobes only slightly produced. Dentate lobe a little longer than inner lobe, with 3 transverse rows of fine denticles. Inner lobe somewhat conical in shape. Basipod well defined at base and armed with 1 seta at inner distal angle. Exopod plate-like, ending in a row of fine denticles. Endopod represented by a seta, as long as exopod in lateral view.

Pleopod 1 absent.

Uropod ( Figs 22 a–b): sympod 2.7 times as long as maximum width, dilated in distal half of inner margin, bearing inhomonomous row of 4 serrulate spines, proximal 3 spines slender, equal in size; ultimate spine thickest and largest. Exopod cylindrical, 41.3% of sympod length and armed with 1 apical and 1 subapical, barbed setae; outer seta longer than inner one. Endopod falcate, 88.9% of sympod length, distal inner margin ornamented with spinules and with 2 unequal, long setae at proximal fourth of outer margin; inner seta longer than outer one, spur somewhat slender and incurved.

Pleotelson ( Figs 22 a–b): slightly protruded, with 1ventral seta on either side at base of caudal furca; seta shorter than furca.

Anal operculum ( Fig. 22 a): medially concave in dorsal view.

Caudal furca ( Figs 22 a–b): longer than maximum width, bearing 1 terminal and 3 inner spines with serrulate margins and 2 unequal dorsal plumose setae; each spine with transverse row of delicate spinules at base; furcal organ small, ventral.

Description of adult female. Total body length 1.10 mm, paratypes 0.97–1.26 mm. Body and all appendages except Th VIII as in male.

Th VIII ( Fig. 18 c): small, broadly triangular and plate-like lobe.

Description of juvenile ( Figs 23 a–e). Total length 0.73 mm. Body form as in adult, 8.2 times longer than maximum width. Pleomeres wider than thoracomeres. Head 1.2 times as long as wide. Body segmentation and various details of cephalic appendages as in adult, but differing in the following respects: Th I–IV adult-like; Th V–VII ( Figs 23 a–c) rudimentary; epipod present; basis without seta; exo- and endopod unsegmented; exopod slightly shorter than endopod and with 2 apical weak setae; endopod unarmed. Th VIII ( Fig. 23 d) rudimentary; protopod shorter and outer lobe subtriangular and fused with protopod. Basipodal and endopodal setae not discernible. Dentate lobe rectangular, smooth, as long as inner lobe. Pleotelson as in adult. Uropodal exopod straight, 35.6% of sympod length and endopod 77.7% of sympod length; armature as in adult. Furcal spines relatively small, without any basal spinules.

Etymology. The specific epithet alluding to the apparent resemblance of the new species with H. indica insofar as the spine row of the uropodal sympod on distal margin (Latin pseudo = spurious); gender feminine.

Remarks. The new species is closely related to H. indica in the following respects: number and pattern of sympodal spines; unequal aesthetascs on ultimate and penultimate segments; 10 main teeth on free labral margin; setae on uropodal endopod more or less equal to endopodal spur ( Ranga Reddy & Schminke 2005).

The new species is strikingly different from H. indica in that the penile lobes are much shorter. It also differs from the latter in the following features: first exopodal segment of Th I unarmed vs. armed; the male Th VIII outer lobe smooth and fused with protopod vs. denticulate and fused with penile region; proximal endite of maxilla bearing 2 vs. 3 setae; mid-inner margin of maxilla with 2 vs. 3 setae; number of teeth on pars molaris 6 vs. 5. Also, spine pattern on sympod of H. pseudoindica n. sp. is same as in the Indian H. indica (see Ranga Reddy & Schminke 2005) and the Madagascan H. milloti and H. jeanneli (see Delamare Deboutteville & Paulian 1954).

Figures

FIGURE 1. Map showing the distribution of Habrobathynella ajraoi n. sp. (▲), H. parakrishna n. sp. (■), and H. pseudoindica n. sp. (♦).

FIGURE 16. Habrobathynella pseudoindica n. sp., paratype male, habitus, lateral.

FIGURE 17. Habrobathynella pseudoindica n. sp., holotype male: (a) antennule, dorsal; (b) antenna, lateral; (c) labrum, ventral; (d) mandible, lateral; (e) mandible, pars incisiva.

FIGURE 18. Habrobathynella pseudoindica n. sp., holotype male: (a) maxillule, lateral; (b) maxilla, lateral; (c) Th VIII, lateral.

FIGURE 19. Habrobathynella pseudoindica n. sp., holotype male. (a – d) Th I – IV (arrow pointing lack of seta on Th I first endopodal segment).

FIGURE 21. Habrobathynella pseudoindica n. sp., holotype male, Th VIII. (a) latero-external; (b) latero-internal; (c) anterior; (d) posterior; (e) ventral.

FIGURE 22. Habrobathynella pseudoindica n. sp., holotype male: (a) pleotelson, dorsal; (b) same, lateral.

FIGURE 23. Habrobathynella pseudoindica n. sp., male juvenile. (a – c) Th V – VII; (d) Th VIII; (e) pleotelson, ventral.