Talorchestia buensis Bhoi, Patro & Myers, 2023

Bhoi, Gitanjali, Myers, Alan A., Khatua, Rohit & Patro, Shesdev, 2023, Talorchestia buensis sp. nov. (Senticaudata, Talitridae), a new species of amphipod from West Bengal, east coast of India, Zootaxa 5315 (1), pp. 77-82 : 78-81

Talorchestia buensis Bhoi, Patro & Myers , sp. nov.

Figs. 1–2

Type Material: Female holotype. 9.5mm, (ZSI/ EBRC /Cr14799), near Kadirabad Char (21°52’34.97”N, 87°58’58.75”E), West Bengal, India, from sandy beach, 07/10/2022, Coll. Rohit Khatua. Paratypes: ZSI/ EBRC / Cr 14800, 1 male, 12 mm, ZSI/ EBRC / Cr 14801, 1 male, 10.2 mm, ZSI/ EBRC / Cr 14802, 1 female, 8.5mm same data as holotype .

Etymology: The species is named after Berhampur University where the species was identified. The species is named as bu ensis based on the first letters of B erhampur U niversity.

Diagnosis: Palm of male gnathopod 2 without distal protuberance, pereopod 7 longer than pereopod 6, length of the antenna 2 reaching more than half of the body, endopod of uropod 2 with double rows of setae, telson with 10–12 robust setae in each lobe.

Description: Based on Male paratype, 12 mm.

Head. Eyes medium. Antenna 1 short, reaching midpoint of peduncular article 4 of antenna 2, peduncular article 2 is longer than article 3, flagellum with five articles ( Fig. 1 ). Antenna 2 slightly longer than half body length; peduncular articles elongate; article 5 longer than 4; flagellum with 24 articles. Mandible lacinia 5 cuspidate; Maxilliped palp broad; article 2 with distomedial lobe; article 4 reduced, button-shaped.

Pereon. Coxal plate 1 smaller than 2. Coxal plate 5 and 6 is bilobate. Gnathopod 1 sexually dimorphic; parachelate; posterodistal margin of propodus and carpus each with strongly produced narrow lobe covered in palmate setae; carpus elongate, slender, length = 4x breadth; propodus subrectangular, palm transverse; dactylus much longer than palm. Gnathopod 2 sexually dimorphic, subchelate; basis slender with rows of setae on posterior and anterior margins; posterior margin of merus, carpus and propodus without lobe; propodus pyriform, palm very oblique, with about 11 evenly spaced relatively elongate robust setae; dactylus fitting palm, distally recurved and with proximal sinus on posterior margin. Pereopod 3–7 cuspidactylate. Pereopod 4 slightly shorter than pereopod 3; dactylus thickened proximally with notch midway along posterior margin. Pereopod 6 longer than pereopod 5. Pereopod 7 longer than pereopod 6.

Pleon. Pleopods 1–3 well developed. Epimera 1–3 each with small acute tooth on posteroventral corner. Epimeron 1 with 6 robust setae on the anteroventral margin. Epimera 2–3 posterior margin with 4 and 6 small setae respectively. Uropod 1 peduncle with two marginal rows of robust setae and a distolateral robust seta; endopod subequal in length to exopod; endopod with a double rows of marginal setae; exopod without marginal setae. Uropod 2 peduncle with marginal rows of setae, exopod with three marginal setae in single distal row; endopod with double row of setae. Uropod 3 uniramus; ramus shorter than peduncle. Telson completely cleft and apically incised, with 10–12 marginal and apical robust setae per lobe.

Female holotype: 9.5 mm. Sexually dimorphic. Oostegites with simple tip ( Fig. 1 ). Antenna 2 flagellum with 16 articles. Gnathopod 1 sexually dimorphic and without narrow lobe on merus and carpus. Gnathopod 2 smaller than that of male and mitten shaped with small setae on posterior margin of merus, carpus and propodus ( Fig. 2 ).

Habitat. Under casuarina plant leaf litter on sandy beach with an approximate distance of 7 meters from the water mark during the high tide.

Remarks. Previously, three species, T. martensii Chilton (1921) , T. affinis Maccagno, 1936 and T. lakshadweepensis Trivedi, Lowry &Myers, 2020 have been reported from India. Talorchestia martensii was described by Chilton (1921) from Chilka lagoon and later reported by Lyla et al. (1998) from the South Indian coast. However, Lowry and Springthorpe (2019) considered that the species described by Chilton (1921) represents an unrecognised species and that the material described by Lyla et al. (1998) also represents an undescribed species. Talorchestia buensis sp. nov. differs from the species described as T. martensii by Chilton (1921) in having peduncular article 5 is longer than article 4, whereas in T. martensii Chilton (1921) article 4 and 5 of antenna 2 are subequal in length. In addition, T. martensii (as described by Chilton, 1921) has a single row of setae on the uropod 2 endopod, whereas in T. buensis sp. nov. there is a double row. Talorchestia martensii as described by Lyla et al. (1998) from south Indian coast has a single median distal robust seta on the peduncle of uropod 3 and about 7 setae on the telson whereas T. buensis sp. nov. has eight robust setae on the peduncle of uropod 3 and more than 10 robust setae in each lobe of the telson.

T. buensis sp. nov. is very closely related to T. martensii described by Miyamoto and Morino (1999) from Taiwan, but differs in the structure of the male gnathopods. In T. buensis sp. nov., the carpus of gnathopod 1 is very elongate, 4 x as long as broad, that of T. martensii is only about 3 x as long as broad and the palmate lobes on the carpus and propodus are elongate and narrow in T. buensis sp. nov., whereas in T. martensii they are only moderately extended with broad bases. In gnathopod 2, the palm of T. buensis sp. nov. bears long relatively slender robust setae whereas in T. martensii , these setae are short, stout and weakly curved. The gnathopod 2 dactylus of T. buensis sp. nov. is distally strongly recurved, whereas in T. martensii , it is weakly and evenly convex.

Of the other species of Talorchestia recorded from India, T. affinis has five serrated setae on the gnathopod 1 propodus palm but these are absent in T. buensis sp. nov.. Pereopod 6 and pereopod 7 are subequal in length in T. affinis as well as in T. lakshadweepensis , but in T. buensis sp. nov. pereopod 6 is shorter than pereopod 7. The uropod 1 of T. lakshadweepensis is without distolateral robust setae which is present in T. buensis sp. nov.

Of the world species, T. buensis sp. nov. differs from T. mindorensis , T. palawanensis , T. terraereginae , T. yoyoae , T. bunaken and T. spinipalma , in the absence of a distal protuberance on the palm of male gnathopod 2 which is present in all the six species. Talorchestia qeshm has two small robust setae on the anteroventral margin of epimeron 1 ( T. buensis sp. nov. has six). Talorchestia anakao Lowry & Springthorpe, 2019 , T. brucei , T. seringat and T. sipadan , have less than 10 robust setae on each telson lobe (10–12 in T. buensis sp. nov.). Talorchestia buensis sp. nov. differs from T. australis K.H. Barnard, 1916 and T. franchetti Macagno, 1936 , in having 24 articles on the flagellum of antenna 2 (15 in T. australis and T. franchetti ). In T. dili and T. gracilis Dana, 1852 , antenna 2 is as long as the body, whereas in T. buensis sp. nov., it is only slightly longer than half the length of the body. In T. telluris ( Spence Bate, 1862) , antenna 2 is scarcely one quarter the body length. Gnathopod 1 dactylus of T. dampieri Lowry & Springthrope, 2015 is with an anterior denticular patch which is absent in T. buensis sp. nov.. In T. morinoi Othman & Azman, 2007 the exopodite of uropod 1 is slightly longer than endopodite whereas in T. buensis sp. nov. they are subequal. In T. diemenensis ( Haswell, 1880) , the dactylus of gnathopod 1 is short whereas in T. buensis sp. nov. the dactylus of that appendage is long.

Descriptions of T. pollicifera Stimpson 1855 , T. landanae Schellenberg, 1925 and T. cookii Filhol, 1885 are insufficiently described for comparison with T. buensis sp. nov.

Figures

FIGURE 1. Talorchestia buensis sp. nov., male paratype, 12 mm, ZSI/EBRC/Cr14800, female holotype, 9.5mm, ZSI/EBRC/ Cr14799 (oostegite)

FIGURE 2. Talorchestia buensis sp. nov., paratype, male, 10.2 mm, ZSI/EBRC/Cr14801, paratype, female, 8.5 mm, ZSI/ EBRC/Cr14802.