Atopobathynella nelloreensis, Bandari & Shaik & Ranga Reddy, 2017

Bandari, Elia, Shaik, Shabuddin & Ranga Reddy, Yenumula, 2017, A phylogenetic review of the genus Atopobathynella Schminke, 1973 (Crustacea, Malacostraca, Bathynellacea) with three new species from southeastern India, Journal of Natural History 51 (35 - 36), pp. 2143-2184 : 2153-2160

Atopobathynella nelloreensis sp. nov.

( Figures 8 – 13 )

Type locality

Borewell at Krishnapatnam (14º03 ʹ 26 ʹʹ N 79º27 ʹ 33 ʹʹ E) near Nellore town of Andhra Pradesh State, South India ( Figure 1 (a)) .

Type material examined

Holotype adult male (ZSI C5856/2/a – m), allotype adult female (ZSI C 5857/2/a – e), dissected on eight and 11 slides, respectively. Paratype adult female (ZSI C 5858/2), mounted whole on a slide. 21 January 2005 and 17 August 2005, Coll . B . Elia.

Diagnosis

Body size up to 0.79 mm, 12 times as long as wide; second antennular segment of male bearing antennal organ represented by a small digitiform process; labrum with 10 main teeth and numerous tiny denticles in the middle; hand-shaped distal tooth of pars molaris pointed; male Th VIII massive, expanded horizontally with somewhat rectangular protopod. Dentate lobe somewhat comb-like. Th VIII female as small crescentic lobe; uropodal sympod with inhomonomous row of six or seven spines, proximal five or six spines uniform in length, ultimate one largest; a seta occurring in the distal third of outer margin, opposite to spine row; anal operculum massive, triangular, reaching the end of caudal furca.

Etymology

The species is named after a town called Nellore, which is close to the type locality; the name is an adjective for place name, made with the Latin suffix ‘-ensis’.

Description

Male (based on holotype). Total body length of holotype 0.76 mm. Body elongated, cylindrical and 12 times as long as wide. Head 45% longer than first two thoracomeres combined and 1.2 times as long as wide.

Antennule ( Figure 9 (a)) 6-segmented. First segment with one seta on distal inner corner, two simple dorsal setae, two plumose setae, one ventral simple seta at outer distal corner, and one simple seta on outer margin. Second antennular segment with antennal organ ( Figures 8 (b) and 9(a)) represented by a greatly reduced digitiform process, not extending up to posterior margin of segment, and three plumose setae on outer distal margin. Third segment with a group of three simple setae on outer distal margin, two small, simple setae on distal margin, and one simple seta on inner distal margin. Inner flagellum of third segment long, over-reaching midlength of next segment, partially fused with fourth segment and armed with three simple setae. Fourth segment with one simple seta on dorso-distal margin, one plumose seta beside apophysis. Apophysis short and with two plumose setae. Fifth segment with two simple setae on inner dorsal margin, one long simple seta on outer dorsal margin and three aesthetascs on dorso-distal margin. Sixth segment with six terminal setae and three terminal aesthetascs.

Antenna ( Figure 9 (c)) small, 1-segmented, twice as long as wide, with two terminal setae (one plumose and one simple) and one subterminal simple seta.

Labrum ( Figure 9 (d)) free margin with tiny median denticles, flanked on either side by five nearly uniform main teeth. Ventral surface ornamented with one pair of teats and two vertical rows of spinules, as illustrated.

Mandible ( Figure 9 (e)) distal part of pars incisiva with three unequal, curved and pointed teeth. Tooth on ventral edge small, pointed and lying close to pars molaris. Pars molaris consisting of five spines. Distal claw wide and hand-shaped, with five spinules on outer margin. Palp 1-segmented, with one apical seta, which is seven times as long as palp.

Paragnaths ( Figure 9 (f)) coupler short, rounded and ornamented with fine spinules distally. Lateral arms rather short, broad, antero-laterally directed and without ornamentation.

Maxillule ( Figure 9 (g)) with two endites. Proximal endite with two small, claw-like setae distally, one simple lateral seta and one dorsal simple seta at midlength. Distal endite with four terminal and two subterminal claws and three simple setae on outer distal margin.

Maxilla ( Figure 9 (h)) 4-segmented, basal segment 1.6 times as long as wide and with two setae at inner distal corner. Second segment 0.8 times as long as basal segment and with four setae. Third segment as long as basal segment and with 10 setae. Fourth segment smallest with seven setae. Setal formula 2 – 4-10 – 7. Th I – VII ( Figures 10 (a – d) and 11(a – c)) well-developed, Th I – IV gradually increasing in size and Th V – VII nearly similar size. Well-developed, club-shaped epipod on Th II – VII, at least 0.7 times as long as basis. Coxa of all Th small, basis with one simple seta, extending beyond midlength of first endopodal segment on Th I, but extending beyond first endopodal segment on Th II – VII. Exopod of Th I 1-segmented, 0.4 times as long as endopod, with one terminal plumose seta and one subterminal seta. Exopod of Th II – VII also 1-segmented, nearly 0.7 times as long as endopod, with one long, terminal plumose seta, one short subterminal seta on outer corner and one subterminal plumose seta on inner margin. Spinule row at base of terminal seta. Endopod 4-segmented. Setal formulae: Th I 1 + 0/1 + 1/1 + 0/2(0), Th II – VII 0 + 0/0 + 1/0 + 1/1(0)

Th VIII ( Figures 12 (a – b) and 8(c)): parallel to body, rectangular in lateral view, expanded horizontally, twice as wide as long, protopod massive with frontal protrusion. Dentate lobe protruding and with five strong denticles distally. Outer lobe broad and blunt distally in latero-external view. Inner lobe reaching only the base of dentate lobe and much wider than longer. Basexopod balloon-like, not defined at base in lateroexternal view. Endopod in the form of tiny spine located distally.

Pleopod I ( Figure 12 (c)): present as a plumose seta.

Uropod ( Figures 13 (b) and 8(d)): sympod 3.4 times as long as wide, with inhomonomous row of seven spines on inner margin; distalmost spine 7% longer than others, a short simple seta occurring on outer margin in the distal third of sympod ( Figure 8 (d)). Exopod twice as long as endopod, with one terminal and one subterminal seta; outer seta 1.8 times as long as inner seta. Endopod 72% of sympod length, drawn out distally into a spur, with two lateral setae near base of spur.

Pleotelson ( Figures 13 (a,b) and 8(e)): with one seta at base of caudal furca on either side. Anal operculum ( Figure 13 (a,b)) large, triangular, prominently protruding and almost reaching end of caudal furca.

Caudal furca ( Figure 13 (a,b)): as long as maximum width, with three spines and two unequal dorsal setae. Furcal organ small and ventral.

Description

Female (based on allotype). Total body length of allotype 0.79 mm. Body 14 times as long as maximum width ( Figure 8 (a)). Female differing from male in the details of second antennular segment and thoracopod VIII. Second antennular segment ( Figure 9 (b)) with a group of three plumose setae on outer distal margin.

Th VIII ( Figure 13 (c)): small, crescentic lobe.

Variation

Body size varies from 0.60 to 0.73 mm, mean = 0.67 (n = 10) and the number of spines on uropodal sympod varies between 6 and 7.

Ecology

The type locality is about 5 km away from the Bay of Bengal. Sediment of the borewell composed mostly of coarse sand.

The fauna that co-occurred with the new species included the following taxa: Parastenocaris sp. , Elaphoidella sp. , chironomid larvae and nematodes.

Figures

Figure 1. (a) Map showing the type localities of the three new species of Atopobathynella: A. indica sp. nov., A. nelloreensis sp. nov. and A. inopinata sp. nov., (b) A. indica sp. nov., male habitus, lateral (arrow pointing to Th VIII).

Figure 8. Atopobathynella nelloreensis sp. nov. (b–e) holotype male; (a) allotype female, digital images. (a) habitus, lateral; (b) second antennular segment, arrow pointing to the antennular organ; (c) pleopod I and Th VIII, small arrow pointing to the pleopod and large arrow pointing to the Th VIII; (d) sympod, ventral, arrow pointing to the seta on dorso-lateral surface; (e) pleotelson, arrow pointing to the massive anal operculum.

Figure 9. Atopobathynella nelloreensis sp. nov. (a, c–h) holotype male; (b) allotype female. (a) antennule, dorsal; (b) antennule, dorsal; (c) antenna; (d) labrum, ventral; (e) mandible, lateral; (f) paragnath, ventral; (g) maxillule; (h) maxilla.

Figure 10. Atopobathynella nelloreensis sp. nov., holotype male. (a) Th I; (b) Th II; (c) Th III; (d) Th IV.

Figure 11. Atopobathynella nelloreensis sp. nov., holotype male. (a) Th V; (b) Th VI; (c) Th VII.

Figure 12. Atopobathynella nelloreensis sp. nov., holotype male. (a) Th VIII, latero-internal; (b) Th VIII, latero-external; (c) pleopod and Th VIII.

Figure 13. Atopobathynella nelloreensis sp. nov., (a and b) holotype male; (c) allotype female. (a) pleotelson, ventral; (b) pleotelson and uropod, lateral; (c) Th VIII.