Talorchestia, Dana, 1852

Lowry, J. K. & Springthorpe, R. T., 2019, Talitrid amphipods from India, East Africa and the Red Sea (Amphipoda, Senticaudata, Talitroidea, Talitridae), Zootaxa 4638 (3), pp. 351-378 : 371-373

Talorchestia sp.

( Fig. 14 )

Talorchestia martensii .― Chilton, 1921: 541, fig. 8.

Material. Several specimens, Barkul, Chilka Lake, Odisha State, India (~ 19°41’N 85°12’E), living in holes in mud under dead leaves and weeds, coll., Dr N. Annandale, 21 July 1913 . Male , Barkul , Chilka Lake , Odisha State, India (~ 19°41’N 85°12’E), 1 m . Several specimens, Barkuda Island, Odisha State, India (~ 20°10’N 86°30’E) . 1 male, 1 female, edge of lake, Satpara (Satapada), Odisha State, India (~ 19°40’N 85°26”E) .

Habitat. Living in holes in mud under dead leaves and weeds at the edge of the lake.

Description. Male, based on Chilton, 1921: 541, fig. 8.

Head. Antenna 2 more than half but not exceeding body length; peduncular article 5 subequal in length to article 4; flagellar articles final article large, cone-shaped forming a virgula divina, flagellar articles with apical cluster of ‘imbricated’ setae.

Pereon. Gnathopod 1 coxa smaller than coxa 2; carpus longer than propodus, 1.4 × as long as propodus, 2.2 × as long as broad; propodus subrectangular, anterior margin with 6 groups of robust setae, palm obtuse; dactylus longer than palm, without anterodistal denticular patch. Gnathopod 2 sexually dimorphic; basis slender, anterior margin smooth; ischium without lobe on anterior margin, with distally rounded anterodistal lobe on medial surface; propodus subovate, 1.4 × as long as wide, palm reaching about 47% along posterior margin, smooth, without protuberance or shelf near dactylar hinge, lined with robust setae, with small proximal sinus, posteroproximal corner without spine; dactylus subequal in length to palm, curved, without anteroproximal bump, with posteroproximal sinus and small projection. Pereopods 2–4 coxae as wide as deep. Pereopods 3–7 dactyli without anterodistal patch of many rows of tiny setae. Pereopods 6–7 not sexually dimorphic. Pereopod 6 coxa posterior lobe with anteroventral corner rounded, not produced. Pereopod 7 posterodistal lobe present, rounded, produced downwards almost to merus.

Pleon. Pleopods 1–3 biramous. Epimeron 2 subequal in length to epimeron 3, posterior margin smooth. Epimeron 3 posterior margin smooth, with minute setae, posteroventral corner with large subacute tooth. Uropod 1 peduncle with about 10 robust setae, distolateral robust seta absent; endopod subequal in length to exopod, with 5 marginal robust setae in one row. Uropod 2 peduncle with 6–9 robust setae; endopod subequal in length to exopod, with 4 marginal robust setae in one row; exopod with 4 marginal robust setae in one row. Uropod 3 peduncle with 3 robust setae; ramus not fused to peduncle, 3.5 × as long as broad, linear (narrowing), with 4–5 marginal robust setae. Telson dorsal midline vestigial or absent, 7 setae per lobe.

Female (sexually dimorphic characters). Gnathopod 1 carpus 1.7 × as long as propodus, 2.8 × as long as broad; propodus anterior margin with 4 groups of robust setae. Gnathopod 2 mitten-shaped; basis expanded anteromedially; 2.3 × as long as wide, lined with robust setae, without palmar sinus.

Remarks. Based on description and figure 8 of Chilton (1921) these specimens appear to be a misidentification of Talorchestia martensii . The illustrations indicate an undescribed species of Talorchestia . The specimens used in the description no longer exist and the females and juveniles available are inadequate to describe the species, (Matthew Shaw, Canterbury Museum, Christchurch, pers. comm.).

FIGURE 13. Talorchestia anakao sp. nov., holotype, male, 11 mm, MNHN-IU-2008-23655, female, 9 mm, MNHN-IU-2008- 23656, Plage Est, Nosy Vé. Scale lines for G1-2 represent 0.5 mm, remainder represent 0.1 mm (after Ledoyer, 1986: 1017, fig. 402).

Talorchestia sp. belongs to the species group without a proximal protuberance on the palm of male gnathopod 2 and a large posteroventral tooth on epimeron 3. It appears to be the only species in this group with a posteroventral lobe on the basis of pereopod 7 and with only one row of marginal robust setae on the endopod of uropod 1. It shares a number of characters with T. anakao including a small palmar sinus on the propodus of gnathopod 2 and a large subacute tooth on the posteroventral corner of epimeron 3. They differ in that T. sp. has only a single row of marginal robust setae along the endopod of uropod 1.

Talorchestia sp. is similar to T. bunaken and T. martensii of Miyamoto & Morino (1999). It differs in having gnathopod 2 propodus about 1.5 × as long as broad (about 2 × in T. bunaken and T. martensii ); uropod 1 and 2 endopod with marginal robust setae in one row (two rows in T. bunaken and T. martensii ). It differ from T. bunaken in having the dactylus of gnathopod 2 reaching between 46–50% along the posterior margin (71–75% in T. bunaken ); propodus palm with small sinus (without palmar sinus in T. bunaken and T. martensii ) and a curved dactylus (sinusoidal in T. bunaken and T. martensii ).

Distribution. India. Barkul, Chilka Lake, Odisha State ( Chilton 1921).

Figures

FIGURE 14. Talorchestia sp., male, female, Barkul, Chilka Lake Odisha State, India. Juveniles and young males “a-f”, 6–9 mm (after Chilton, 1921: 541, fig. 8).