Chilikorchestia chiltoni, Thacker & Myers & Trivedi & Mitra, 2024

Thacker, Dimple, Myers, Alan A., Trivedi, Jigneshkumar N. & Mitra, Santanu, 2024, On a small collection of amphipods (Crustacea, Amphipoda) from Chilika Lake with the description of three new species and a new genus, Zootaxa 5446 (3), pp. 383-404 : 390-394

publication ID	https://doi.org/ 10.11646/zootaxa.5446.3.4
publication LSID	lsid:zoobank.org:pub:95C3BE52-AA7A-48BE-A889-6ADD280B1792
DOI	https://doi.org/10.5281/zenodo.11101941
persistent identifier	https://treatment.plazi.org/id/0D3D87BB-1A54-BF60-FF79-67780B5DCC0E
treatment provided by	Plazi
scientific name	Chilikorchestia chiltoni
status	sp. nov.

Treatment

Chilikorchestia chiltoni sp. nov.

( Figs. 2b View FIGURE 2 & 6–8 View FIGURE 6 View FIGURE 7 View FIGURE 8 ).

Material examined. Holotype male, 10.5 mm ( LFSC.ZRC-201), Honeymoon Island , Chilika Lake (19°33'17"N 85°08'39"E), Odisha, India, 2 September, 2018, coll. D. Thacker. GoogleMaps Paratypes, 1 male, 11 mm, 1 female, 4.5 mm ( LFSC.ZRC-202), same data as holotype GoogleMaps .

Etymology. The new species is named in honor of Charles Chilton, who worked as a Professor of Zoology at Canterbury University College, New Zealand and made a significant contribution to crustacean taxonomy. Charles Chilton was also a first researcher to publish a paper on amphipod diversity of Chilika Lake.

Description. Based on holotype male (10.5 mm) and paratype female (4.5 mm).

Head. Eyes medium, round. Antenna 1 slightly extending the distal end of the antenna 2 article 4 ( Fig. 6 View FIGURE 6 : A1). Antenna 2 less than half of the length of the whole body; peduncular articles moderately incrassate; peduncular article 5 1.6 x as long as article 4; article 5 with some small robust setae ( Fig. 6 View FIGURE 6 : A2). Labrum distal margin rounded with a row of small setae ( Fig. 6 View FIGURE 6 : Lb). Labium with distally setose rounded plates ( Fig. 6 View FIGURE 6 : L). Mandible left lacina moblis 5 dentate ( Fig. 6 View FIGURE 6 : Md). Maxilla 1 vestigial with only 1 article. outer plate with 8 dentate setae; inner plate with 2 plumose setae ( Fig. 6 View FIGURE 6 : Mx1). Maxilla 2 inner plate with a plumose seta on anterodistal corner ( Fig. 6 View FIGURE 6 : Mx2). Maxilliped palp article 2 distomedial lobe well-developed; article 4 reduced, button shaped ( Fig. 6 View FIGURE 6 : Mxp).

Pereon. Gnathopod 1 subchelate; coxa triangular, narrowing distally; basis 1.2 x as long as carpus; ischium subquadrate; merus shorter than carpus; carpus and propodus lobate on the posterodistal corner, palm with 4 robust setae; dactylus simplidactylate, subequal to palm ( Fig. 7 View FIGURE 7 : G1). Gnathopod 2 subchelate, gill lobate; coxa subquadrate, posterior margin with a central shelf, ventral margin with few small hairs on posterior half, ventral margin with irregularly placed small robust setae; basis twice as long as broad, posterior margin with 4 small robust setae; ischium small; carpus small subrectangular; propodus oval, palm transverse with several small robust setae and a long protuberance at the posterodistal corner; dactylus longer than palm, fits into the groove formed on the protuberance ( Fig. 7 View FIGURE 7 : G2). Pereopod 3–7 bicuspidactylate ( Figs. 7 View FIGURE 7 : P3–P7). Pereopod 3 coxa subquadrate; basis long with robust setae on both margins; merus 1.5 x as long as carpus; propodus subequal to carpus ( Fig. 7 View FIGURE 7 : P3). Pereopod 4 smaller than pereopod 3; basis long with robust setae on both margins; merus 1.6 x as long as carpus; propodus 1.2 x as long as carpus ( Fig. 7 View FIGURE 7 : P4). Pereopod 5 basis expanded; merus subequal to carpus; propodus 1.3 x as long as carpus ( Fig. 7 View FIGURE 7 : P5). Pereopod 6–7 similar, except pereopod 6 basis oval were as pereopod 7 basis subquadrate ( Figs. 7 View FIGURE 7 : P6 & P7).

Pleon. Uropod 1 peduncle longer than rami with 7 robust setae in two margins, distolateral robust setae present, small, with simple tip; exopodite subequal to endopodite, without marginal robust setae; endopodite with 3 robust setae on inner margin ( Fig. 7 View FIGURE 7 : U1). Uropod 2 peduncle little longer than rami, with 5 robust marginal setae; endopodite subequal to exopodite, with 2 marginal setae on inner margin; exopodite with 4 robust setae in two margins ( Fig. 8 View FIGURE 8 : U2). Uropod 3 uniramous; peduncle longer than ramus with 2 robust setae; ramus narrowing distally ( Fig. 8 View FIGURE 8 : U3). Telson slightly longer than broad, apically notched, with 5–6 robust setae on each lobe ( Fig. 8 View FIGURE 8 : T).

Female (sexually dimorphic characters). Gnathopod 1 parachelate; posterior margin of carpus and propodus without lobe; propodus subrectangular. Gnathopod 2 mitten-shaped.

Remarks. This is the first record of a member of the Plarorchestiinae occurring in India. Previous records of Platorchestia platensis (Krøyer, 1845) from India ( Barnard, 1935, Dev Roy et al., 2009, Surya Rao, 1972, Thilagavathi et al., 2013) are erroneous.

Distribution. Currently known only from the type locality.