Grandidierella macronyx K.H. Barnard, 1935

Thacker, Dimple R., Patro, Shesdev, Bhoi, Gitanjali, Myers, Alan A., Kumar, R. Kiran & Trivedi, Jigneshkumar N., 2025, On the genus Grandidierella Coutière, 1904 (Amphipoda: Aoridae) of India with the description of two new species, Zootaxa 5716 (4), pp. 451-482 : 469-472

publication ID	https://doi.org/10.11646/zootaxa.5716.4.1
publication LSID	lsid:zoobank.org:pub:E9A4AB31-9B78-4291-B6AF-562D5268BD10
persistent identifier	https://treatment.plazi.org/id/03B23D4B-FFED-FFF4-9F82-E58BFEA3F975
treatment provided by	Plazi
scientific name	Grandidierella macronyx K.H. Barnard, 1935
status

Treatment

Grandidierella macronyx K.H. Barnard, 1935 View in CoL

Figs. 2A View FIGURE 2 , 11 View FIGURE 11 & 12 View FIGURE 12

Grandidierella macronyx Barnard, 1935: 300 View in CoL .

Grandidierella megnae View in CoL — Chillon 1921: 548 (in part), fig. 10 (m, n, o).

Grandidierella macronyx View in CoL — Asari & Myers 1982: 238, figs. 1–2.

Diagnosis

Male gnathopod 1 basis large with both margins convex, carpus large with one long conical tooth extending from the inner margin and posterodistal corner produced into a small conical tooth. Epimera 1–3 posteroventral corners with a thick seta and a single thin seta on distodorsal margin on each.

Material examined

India • 2 ♂, 6.0 mm; Tithal , Gujarat; 20°35'26"N, 72°48'45"E; 12 Mar 2024; D. R. Thacker leg.; LFSC.ZRC-287 GoogleMaps .

Ecology type. Collected from muddy substrate. Salinity 35±2 PSU .

Description. Based on male 6 mm.

ANTENNA 1 ( Fig. 11 View FIGURE 11 ). Slender, subequal to antenna 2; length ratio of peduncular articles 1–3 1:1.18:0.52; primary flagellum 1.2 × length of peduncle; accessory flagellum one articulate.

ANTENNA 2 ( Fig. 11 View FIGURE 11 ). Stout, length ratio of peduncular articles 3–5 1:2.14:2; flagellum short with 7 articles, article 3 to 7 each with a robust spine.

MAXILLA 1 ( Fig. 11 View FIGURE 11 ). Outer plate with 10 apical robust setae; palp article 2 with 5 apical robust setae and 4–5 simple setae.

MAXILLA 2 ( Fig. 11 View FIGURE 11 ). Inner plate apically setose, oblique setal row present; outer plate apically setose.

MANDIBLE ( Fig. 11 View FIGURE 11 ). Palp 3 articulate, ratio of three articles 1–3 1:1.47:1.03; incisor with 5 cusps, lacinia mobilis with 3 cusps, 6 accessory setae present.

MAXILLIPED ( Fig. 11 View FIGURE 11 ). Inner plate with several plumose setae; outer plate with four apical thick setae and 6 marginal robust setae; palp article 2 longest; article 4 with apical nail.

GNATHOPOD 1 ( Fig. 12 View FIGURE 12 ). Coxa trapezoidal; basis very broad with both margins convex, 1.3 × longer than broad, posterior margin with a single simple seta; ischium small; merus twice the length of ischium; carpus large, elongate, 1.6 × as the length of basis, 1.8 × longer than broad with a very long conical tooth extending from the inner margin, posterodistal corner produced into a small conical tooth, anterior margin with a few small setae, posterior margin several medium sized setae; propodus with both margins curved; dactylus subequal to propodus, both margins smooth.

GNATHOPOD 2 ( Fig. 12 View FIGURE 12 ). Coxa longer than broad; basis 3.8 × longer than broad, both margins bare; ischium small subquadrate; merus 1.8 × the length of ischium; carpus 2.85 × longer than broad, anterodistal corner with a pair of long setae; propodus suboval, 2 × longer than broad, anterior margin sparsely setose, posterior margin with one or two small setae; dactylus subequal in length to palm, distal part of inner margin serrated.

PEREOPOD 3–4 ( Fig. 12 View FIGURE 12 ). Similar; basis 3.2 × longer than broad, anterior margins with 8–10 small setae, posterior margin with 6–7 medium sized setae; ischium small, subrectangular, posterodistal corner with a single seta; merus around 1.4 × the length of propodus; carpus with one or two small setae on anterior margin, 6–7 simple setae on posterior margin; propodus slender, 1.5 × the length of dactylus, with several setae on anterior margin, two setae on posterior margin, anterodistal corner with a tuft of few simple setae, posterodistal corner with a single seta; dactylus slender.

PEREOPOD 5 ( Fig. 12 View FIGURE 12 ). Basis subrectangular anterior margin with six small setae, posterior margin with few small and medium sized setae; ischium small with a pair of setae on anterodistal corner; merus subequal to propodus, with four setae on anterior margin, and a tuft of three setae on anterodistal corner; carpus with two setae on anterior margin, a tuft of two setae on anterodistal corner, posterior margin with two robust setae; propodus 1.3 × the length of carpus, anterior margin with three setae, anterodistal corner with a tuft of three simple setae, posterior margin with four robust setae; dactylus small, 0.4 × the length of propodus.

PEREOPOD 6 ( Fig. 12 View FIGURE 12 ). 0.9 × the length of pereopod 7; basis subrectangular, anterior margin with eight small setae, posterior margin with five robust setae and sparsely placed plumose setae, anterodistal corner with a tuft of three setae; ischium longer than broad with a pair of setae on anterodistal corner; merus 5 × longer than broad, anterior margin with few small setae, posterior margin with two small thin and three long thick setae, anterodistal corner with two thick setae, posterodistal corner with one thick long setae; carpus 0.8 × the length of merus, anterior margin with two small setae, posterior margin with one small; both distal corners with two thin setae; propodus 0.9 × the length of basis, anterior margin with five spines, posterior margin with one small seta, posterodistal corner with two thick long setae; dactylus 0.5 × the length of propodus.

PEREOPOD 7 ( Fig. 12 View FIGURE 12 ). Basis anterior margin with six small robust setae, posterior margin with eight small robust setae and densely placed long plumose setae; ischium small, subrectangular, with two setae on anterodistal corner; merus 0.9 × the length of basis, anterior margin with four small setae, posterior margin with three thick setae, anterodistal and posterior corner with two setae on each; carpus 0.7 × the length of merus, anterior margin with two setae, posterior margin with three setae, anterodistal corner with one thick seta, posterodistal corner with one thin and two thick setae; propodus subequal to basis, anterior margin with five small spines and three small setae; posterodistal corner with a tuft of long setae; dactylus 0.3 × the length of propodus.

EPIMERA 1–3 ( Fig. 11 View FIGURE 11 ). Posteroventral corner and distodorsal margin of epimera 1–3 each with a single simple seta.

UROPOD 1 ( Fig. 11 View FIGURE 11 ). Peduncle 1.2 × longer than endopodite; endopodite 1.1 × longer than exopodite; inter ramus spine 0.3 × longer than exopodite.

UROPOD 2 ( Fig. 11 View FIGURE 11 ). Peduncle 0.5 × longer than endopodite; exopodite 0.7 × longer than endopodite.

UROPOD 3 ( Fig. 11 View FIGURE 11 ). Uniramous; ramus almost 2.9 × the length of peduncle.

TELSON ( Fig. 11 View FIGURE 11 ). 1.4 × as broad as long, laterodistal corner each with one long robust seta.

Remarks

Chilton (1921) recorded G. megnae on the basis of specimens collected from Chilika Lake, Odisha State, India and also provided three illustrations ( Fig. 10m, n, o View FIGURE 10 ) of male gnathopod 1 to show the variation in morphology among the specimens of G. megnae . Later on, Barnard (1935) re-checked these three illustrations of male gnathopod 1 of G. megnae specimens given by Chilton (1921) and confirmed that they belong to a new species, G. macronyx . The specimen observed here matches with the description and illustrations of G. macronyx given by Asari & Myers (1982). However, there are few variations in the morphology of some body parts as follow: the specimen dissected here does not have the triangular tooth on the inner margin of propodus of male gnathopod 1 ( Fig. 12 View FIGURE 12 Gn1) (versus a triangular tooth present in G. macronyx, Asari & Myers (1982) ; Fig. 1K View FIGURE 1 ); the male gnathopod 1 dactylus is short, reaching only 0.49 x length of carpus ( Fig. 12 View FIGURE 12 Gn1) (versus dactylus very long reaching almost 0.7 × of the carpus length in G. macronyx, Asari & Myers (1982) ; Fig. 1J, K View FIGURE 1 ); telson subrectangular and laterodistal corner each with one long robust seta ( Fig. 11T View FIGURE 11 ) (versus telson rounded and laterodistal corner each with one robust and one simple seta in G. macronyx, Asari & Myers (1982) ; Fig. 1F View FIGURE 1 ).

Distribution

Chilika lake, Odisha, India ( Chilton, 1921; Barnard, 1935), Vellar Estuary, Tamil Nadu, India ( Asari & Myers, 1982) and Tithal, Gujarat (present study), India. In the present study this species is first time reported from the West Coast of India.