Habrobathynella ajraoi, 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 : 141-149

Habrobathynella ajraoi n. sp.

( Figs 2–8 )

Type locality. Farm bore (water temperature 28°C; pH 7.0) at Govindupalem village (17º27′52″N, 82º55′53″E; elevation 28 m), about 20 km from Elamanchili town in Visakhapatnam District, Andhra Pradesh, South India ( Fig. 1 ).

Type material examined. Holotype ♀ (MNHN-IU-2013-11837), dissected on six slides; allotype ♂ (MNHN- IU-2013-11838), dissected on five slides; one paratype ♀ (MNHN-IU-2013-11880), dissected on two slides. 15 May 2009, Coll. V. R. Totakura.

Other material examined. Farm bore at Rambilli village (17º27′52″N, 82º55′53″E, elevation 27 m; temperature 26°C; pH 7.0) in Visakhapatnam District, Andhra Pradesh, South India. 1 ♂ and 2 ♀♀ in alcohol in the first author’s collections. 28 February 2007, Coll. V. R. Totakura.

Diagnosis. On male Th VIII, both dentate and inner lobes moderately produced, extending well beyond basipod level; outer lobe smooth and conical, fused with protopod; exopod plate-like in anterior, posterior, and ventral views, but hook-like in lateral views; basipodal seta distinctly overreaching penile region. Uropodal sympod with dilated, disto-inner margin, having inhomonomous row of 7 spines, proximal 5 spines similar in size, both penultimate and ultimate spines longer than proximal ones and lying apart from each other; and ultimate spine somewhat longer than its neighbor. Mandible: tooth of ventral edge not distinct at base; pars molaris reduced in size, and roughly fork-like with 4 reduced, fused teeth. Antennular apophysis on fourth segment overreaching midlength of next segment; segments 5 and 6 with 3 unequal aesthetascs each, those on the former longer, extending beyond the tip of the latter. Labrum with 8 elongate and incurved teeth on nearly straight free margin. Female Th VIII subovate in outline. Setae on uropodal endopod shorter than spur; outer exopodal seta apical in position and about half as long as inner one. Maxilla with 3 unequal setae on proximal endite; distal segment with 1 claw-like seta as long as apical claw at inner distal corner and 1 on distal margin. Th I with unarmed first endopodal segment. Anal operculum concave. Pleotelson with smoderately long seta at base of caudal furca.

Description of adult female. Total body length of holotype 0.82 mm. Body ( Fig. 2 ) elongate, heavily chitinised and perforated, 8.2 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, 1.6 times as long as first 2 thoracomeres combined.

Antennule ( Figs 2 , 3 a): 6-segmented, measuring 23.3% longer than head, no sexual dimorphism. First segment with 1 plumose seta near outer margin, 1 plumose seta at outer distal corner, 2 plumose and 1 simple setae on dorsal surface subdistally. Second segment with 3 unequal plumose setae in a row on dorsal surface subdistally, 1 ventral plumose seta at outer distal corner and 1 simple seta at inner distal corner. Third segment with 1 plumose seta and 1 long simple seta at outer distal corner, 1 ventral plumose seta near distal margin. Inner flagellum subquadrate, with 3 unequal setae. Fourth segment with stout apophysis, reaching about midlength of next segment and with 2 unequal plumose setae; 2 plumose setae, each occurring on short protuberance, and 1 stub seta on distal margin. Fifth segment with 1 simple seta and 3 unequal aesthetascs on distal margin, all aesthetascs longer than segment 6, and 1 thread-like seta and 2 simple setae at inner distal corner. Sixth segment with 3 unequal, apical aesthetascs and 4 unequal setae.

Antenna ( Fig. 3 b): 2-segmented, proximal segment bare, half as long as distal segment; second segment ovate, 1.6 times as long as wide, with 1 tiny outer proximal seta, 2 unequal terminal setae, of which inner seta plumose and 1.6 times as long as segment, and 1 subterminal dorsal seta.

Labrum ( Fig. 3 c): dentate margin nearly straight, bearing 8 main elongate, pointed and incurved teeth, medial 2 teeth smaller than others; also, 2 pairs of teats on ventral surface, as illustrated; no other ornamentation discernible.

Mandible ( Figs 3 d–e): 3.4 times as long as wide, distal part of pars incisiva with 4 unequal teeth, proximal most tooth small. Tooth of ventral edge comparatively stout, not defined at base and with smooth lateral margins. Pars molaris (‘lobe’) reduced to plate-/fork-like outgrowth, 0.8 times as long as wide, with 4 teeth, proximalmost tooth largest in size and closest to mandibular body; penultimate tooth intermediate in size, 2 distal teeth small and finely denticulate; palp completely absent.

Paragnaths ( Fig. 3 f): coupler rounded and moderately long; lateral lobes short, denticulate spinules (‘ctenidia’) present on coupler and lateral lobes.

Maxillule ( Fig. 4 a): with 2 endites; proximal endite small, oval, carrying 4 unequal claw-like pinnate spines on inner distal margin. Distal endite subcylindrical, 3.8 times as long as wide, and armed with 2 terminal claws, distal one distinctly larger, bent inwards; 3 unequal claws on inner margin and 3 subterminal setae on outer distal margin.

Maxilla ( Fig. 4 b): 2-segmented, bent inwards; basal segment 1.9 times as long as wide, with 3 strikingly unequal setae, lying on small protuberance at inner distal corner. Second segment 1.3 times as long as basal segment and armed with a total of 15 setae including 2 setae at midlength of inner margin and 5 unequal claw-like setae, of which 1 at inner distal corner and 1 at outer distal angle particularly strong. Third segment completely fused with terminal falcate claw with fine spinules on distal inner margin.

Th I–VII ( Figs 5 a–d, 6a–c): Th I–VII gradually increasing in size; epipod absent on Th I; epipod on Th II–VII biarticulate, club–shaped, exceeding midlength of basis. On all thoracopods, coxa with distinct conical projection at inner distal corner and basis with 1 simple slender seta, the latter longer than first endopodal segment on Th I, but shorter on Th II–VII; first endopodal segment without seta. Exopod 2-segmented, about 0.8 times as long as endopod, first segment with 1 dorsal and 1 ventral plumose setae of unequal length. Second segment with 1 subterminal dorsal plumose seta and 1 terminal ventral barbed seta. Endopod 4-segmented, fourth segment smallest. Th I with ctenidia near posterior end of second exopodal segment; endopod without ctenidia. Th II–VII with ctenidia each near posterior end of first and second exopodal segments and also second and third endopodal segments, as illustrated. Setal formulae: Th I: 0/0+1/0+1/2(0); Th II–VII: 0/0+1/0+1/1(0).

Th VIII ( Fig. 4 c): somewhat ovate in outline, not fused at base.

Uropod ( Figs 8 a–b): sympod 3.9 times as long as maximum width, narrow in proximal half, and somewhat dilated in distal half in dorsal view and bearing inhomonomous row of 7 serrulate spines, 5 proximal spines similar in size, penultimate spine slightly longer than proximal ones, ultimate spine longer than, and a little away from, its neighbor and lying at distal corner. Exopod straight, 21% of sympod length, slightly indented laterally close to base ( Fig. 8 c) and armed with 2 apical, unequal barbed setae, outer seta about half as long as inner seta. Endopod falcate, 41.5% of sympod length, with 2 unequal subapical setae, shorter than endopodal spur.

Pleotelson ( Figs 8 a–b): only slightly produced and rounded at postero-lateral angle, with 1 moderately long, ventral seta on either side at base of caudal furca.

Anal operculum ( Fig. 8 a): medially concave in dorsal view.

Caudal furca ( Fig. 8 a–b): rounded in lateral view, longer than maximum width in dorsal view, bearing 1 terminal and 3 inner spines with serrulate lateral margins and 2 unequal dorsal plumose setae; furcal organ small, ventral.

Description of adult male. Total body length 0.78 mm. Body and all appendages except Th VIII as in female.

Th VIII ( Fig. 7 a–e): subquadrate in lateral view, protopod of moderate size. Outer lobe conical, smooth, fused with protopod, extending but a little beyond base of exopod. Both dentate and inner lobes moderately produced, overreaching exopod. Dentate lobe only slightly longer than inner lobe and with 3 transverse rows of denticles distally. Inner lobe massive, conical in different views. Basipod well defined, ornamented with 1 spinule on inner margin ( Figs 7 a, b, e) and armed with 1 very long seta at inner distal corner, overreaching penile lobe. Exopod hook–like in lateral views, plate-like in anterior, posterior and ventral views, and with fine apical teeth. Endopod represented by a seta.

Pleopod 1 absent.

Etymology. The species is named to honor our good friend and a rare exemplary personality, Mr. Adusumilli Jagannadha Rao, ex-Finance Officer, Acharya Nagarjuna University; the specific epithet, coined by prefixing the initial letter of his surname as well as middle name to the last name, is a noun in the genitive singular.

Distribution and ecology. H. ajraoi n. sp. was collected only from the phreatic waters of two farm bores, one of which is the type locality; it was accompanied by some unidentified non-parastenocaridid harpacticoids.

Remarks. The new species fulfills all the generic criteria, as revised by Ranga Reddy & Totakura (2010). Within Habrobathynella , H. ajraoi n. sp. is closely related to the Indian H. vidua Ranga Reddy & Totakura, 2010 , in the following respects: ultimate and penultimate spines on uropodal sympod longer than proximal ones; uropodal endopod with two setae shorter than endopodal spur; penile region of male Th VIII is moderately extended; two setae present on mid-inner margin of maxilla; ultimate and penultimate antennular segments with longer and unequal aesthetascs. The new species, however, differs from H. vidua by having eight long, curved vs. ten short, straight main labral teeth; mandibular pars molaris fork-like with four, fused teeth vs. subpyriform with five articulate teeth; pleotelson setae present vs. absent; uropodal exopod short vs. long; male Th VIII with small, smooth outer lobe fused to protopod vs. large, denticulate and fused to penile region; basipod with vs. without spinule on inner angle; proximal endite of maxilla with three setae vs. one seta; and seta on first exopodal segment of Th I absent vs. present (see Ranga Reddy & Totakura 2010). Female Th VIII is ovate and long vs. elliptical and short.

The new species is so distinctly different from the other congeners that a detailed comparison is redundant. All in all, the new species stands out in the genus Habrobathynella especially by its mandibular features, which are somewhat reflective of the close affinity between this genus and the African Haplophallonella Serban & Coineau, 1975 (see Serban & Coineau 1975).

Figures

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

FIGURE 2. Habrobathynella ajraoi n. sp., paratype female, habitus, lateral.

FIGURE 3. Habrobathynella ajraoi n. sp., allotype male (a), holotype female (b – f): (a) antennule, dorsal; (b) antenna, lateral; (c) labrum, ventral; (d) mandible, lateral; (e) mandible, pars incisiva; (f) paragnaths, ventral.

FIGURE 4. Habrobathynella ajraoi n. sp., holotype female: (a) maxillule, lateral; (b) maxilla, lateral; (c) Th VIII, lateral.

FIGURE 5. Habrobathynella ajraoi n. sp., holotype female: (a – d) Th I – IV (arrow pointing to lack of seta on Th I first endopodal segment).

FIGURE 6. Habrobathynella ajraoi n. sp., holotype female: (a – c) Th V – VII.

FIGURE 7. Habrobathynella ajraoi n. sp., allotype male, Th VIII. (a) latero-external; (b) latero-internal; (c) anterior; (d) posterior; (e) ventral.

FIGURE 8. Habrobathynella ajraoi n. sp., holotype female: (a) pleotelson, dorsal; (b) same, lateral; (c) uropodal exopod, lateral.