Photis geniculata Barnard, 1935

Brutto, Sabrina Lo & Joseph, Philomina, 2023, A benefit to biodiversity assessment: An Indian survey demonstrates that Cheiriphotis geniculata is a misidentification of the valid species Photis geniculata Barnard, 1935 (Crustacea: Amphipoda), Zootaxa 5389 (2), pp. 227-240 : 230-231

Photis geniculata Barnard, 1935

urn:lsid:zoobank.org:pub:620D0DD2-FE39-4164-8BB3-01752E35DC4D

( Figures 3–8 )

Cheiriphotis geniculata — Surya Rao 1972.— Barnard & Karaman 1991.— Lowry 2010.— Wongkamhaeng et al., 2012.— Joseph et al. 2019;— Nandan et al. 2019.— Joseph & Nandan 2020.— Siddique et al. 2020.— Joseph et al. 2021.— Lo Brutto et al. 2022.

Photis geniculata — Imbach, 1967.— Divakaran et al. 1981.— Bhunia & Choudhury, 1991.— Soemodinoto et al. 1995.— Satheeshkumar 2011.

Material examined. Three males, 3.1–3.3 mm, mangrove area of Valanthakad Island in Vembanad backwater, Kochi , Kerala, 9°55’10.24” N and 76°20’ 01.23” E, 12 April 2022, core sampler; 1.5 m depth ; 5 females (3–3.2 mm). Collection Philomina Joseph .

Description. Head with lateral cephalic lobe highly extended and bearing a large oval eye occupying the extended cephalic region. Eyes situated entirely in terminal portion of lobe. Lateral cephalic lobe apically rounded and extended up to the peduncle article 1 of antenna 1. Head anteroventral margin highly recessed and moderately excavate. Antenna 1 is slender than antenna 2, with peduncle article 3 longer than article 1 and similar in length to article 2, bearing six-segmented flagellum; accessory flagellum absent. Antenna 2 longer, stouter than antenna 1; flagellum composed of five articles. Upper lip (labrum) convex anteriorly, with notch in the middle, covered with minute setae. Lower lip (labium) inner lobe subovoid, outer lobe apex rounded, covered with minute setae. Mandible well developed with 4-dentate incisor, 4-dentate lacinia mobilis, and 4 setae; molar well developed; palp composed of three articles, the 3rd article distally rounded, with setae; article 2 longer than the first and the third. Maxilla 1 inner plate with row of apical setae; outer plate palp biarticulated with apical setae. Maxilla 2 with row of setae in inner plate and several setae at apex. Maxilliped inner lobe subrectangular and smaller than outer lobe: outer lobe broader and rectangular with robust setae and several simple setae. Palp with four articles, the 3rd article slightly expanded distally, half as long as the 2nd article, second is larger with several simple setae on inner margin.

Gnathopod 1 coxa broad and anteroventrally produced; basis long, ischium and merus short, carpus ovoid and setose along the posterior margin, longer than propodus. Gnathopod 2 basis slighly expanded distally, carpus triangular; propodus sexually dimorphic, ovoid, greatly enlarged in male, palm with one long spine on posterior margin and a smaller second spine on the middle and a small prominence between the hinge and second spine; dactylus smooth, geniculate and extending over the palm. In female Gn2 is almost similar in structure to that of male except for the propodus, which is smaller and lacking spines. Pereopods 3–4 with similar type sub rectanguar coxae. Pereopod 5 is smaller than P6 and P7. Pereopod 6 well developed, dactylus geniculate as in P5, P6 and P7. Pereopod 7 elongate, coxae sub-ovate same size as that of other pereopods, basis ovoid, entire propodus extending beyond pereopod 6. Epimera 2 larger and bearing 5 ventral setae and one just above it, laterally. Uropod 1 longer than U2, peduncle with 3 robust dorso-lateral setae; rami unequal, with inner ramus shorter, about 2/3rd of outer ramus and array of strong robust setae. Uropod 2 inner ramus is smaller and stouter with 4 robust dorso-lateral setae on outer margin and three on inner margin and one large robust setae along with few smaller setae apically; outer ramus bearing 3 dorso-medial setae and a large robust seta and few setae apically. Uropod 3 biramous, with inner ramus shorter reaching 2/3rd of length of outer ramus; inner ramus with a robust setae at tip; outer ramus with 5 elongate apical setae. Telson broad, convex apex and uncleft with few simple setae.

Figures

FIGURE 3. Photis geniculata. Male habitus (3.3 mm length). Scale bar 0.3 mm for Hd; 0.1 mm for A1, A2; 0.05 mm for Lbr, Lb, Mx1, Mx2, Mxp.

FIGURE 4. Photis geniculata. Male habitus (3.3 mm length). Scale bar 0.05 mm for Md; scale bar 0.2 mm for Gn 1, Gn 2 (♂), Gn 2 (♀), P3, P4, P5; scale 0.3 mm for Ep1,2,3.

FIGURE 5. Photis geniculata. Male habitus (3.3 mm length). Scale bar 0.2 mm for P6, P7; 0.08 mm for U1, U2, U3, T.

FIGURE 6. Photis geniculata a) male habitus; b) head with extended cepalic lobe, dorsal view; c) antenna 1 without accessory flagellum.

FIGURE 7. Photis geniculata a) gnathopod 1; b) gnathopod 2 (♂); c) gnathopod 2 (♀).

FIGURE 8. Photis geniculata a) uropod 1; b) pereopod 7 with geniculate dactylus; c) uropod 2; d) uropod 3.