Rocasphotis, Souza-Filho & Serejo, 2010

Souza-Filho, Jesser F. & Serejo, Cristiana S., 2010, Two new species of the family Photidae (Amphipoda: Corophiidea: Photoidea) from Brazilian waters, with description of Rocasphotis gen. nov., Journal of Natural History 44 (9 - 10), pp. 559-577 : 567-568

Rocasphotis gen. nov.

Diagnosis

Head anteroventral margin moderately recessed; lateral cephalic lobe weakly extended and apically acute; eyes large, poorly developed, composed by sparse ommatidia, and partly enclosed in the extended lobe. Antenna 1, shorter than antenna 2, peduncular article 1 longer than article 3, accessory flagellum absent. Coxae 1–4, distal margins with sparse setae. Mouthparts forming conical bundle, partly styliform. Epistome not produced. Mandible palp article 3 non-spatulate, margins approximately parallel-sided, with few setae. Maxilla 1 styliform, outer plate slender with two or three stout setae distally and seven robust setae extending down to medial margin; palp slender, article 1 elongate. Maxilla 2 outer plate with a row of subdistal setae; inner plate with a row of facial setae. Maxilliped inner and outer plates enlarged. Coxa 1 wider than coxa 2. Coxa 5 with excavation. Gnathopod 1–2 simple, similar in size, both with carpus and propodus subequal in length. Pereopod 6 large, strongly enlarged, subequal to body length, merus very inflated, longer than carpus and propodus together. Pereopods 5 and 7 dactyli with a subdistal corona of cuticular accessory spines. Uropod 1 peduncle with distoventral corona of cuticular spines. Uropod 3 with reduced inner ramus; outer ramus bi-articulate.

Etymology

Compound name, formed from a cognate genus suffixed ( Photis ) by the type locality Atol das Rocas, Brazil .

Type species

Rocasphotis aiso sp. nov.

Included species

Rocasphotis aiso sp. nov. and Photis sp. E ( LeCroy, 2000) .

Generic remarks

As a whole, Rocasphotis gen. nov. differs from all genera of the family Photidae in having antenna 1 with article 1 longer than article 3, mouthparts forming a conical bundle, parallel-sided (non-clavate) article 3 of palp of mandible (except Papuaphotis ), maxilla 1 styliform with two or three stout setae distally and seven robust setae extending down to medial margin, coxa 1 wider than coxa 2, gnathopods 1 and 2 simple, both with subequal propodus and carpus, pereopod 6 strongly enlarged, subequal to body length and uropod 1 with a corona of cuticular spines on distoventral margin of peduncle.

In addition to the differences cited above, Rocasphotis gen. nov. differs from Dodophotis by the absence of accessory flagellum of antenna 1, and in having a row of facial setae on inner plate of maxilla 1. Also, it can be distinguished from Microphotis by the absence of distoventral inter-ramal process of uropod 1 and in having biramous uropod 3 with bi-articulate outer ramus. It differs from Papuaphotis in having strongly excavated coxa 5, and biramous uropod 3. Finally, Rocasphotis mainly differs from Photis in having lateral cephalic lobe weakly extended and apically acute with eyes partly enclosed in the extended lobe.

Regarding the strongly enlarged pereopod 6, this also occurs in three other species of Photis : P. elephantis Barnard, 1962 , P. trapherus Thomas and Barnard, 1991 and Photis sp. E (LeCroy, 2002) . Nevertheless, we notice herein that these species need to be re-evaluated because they show some characters that neither fit with genus Rocasphotis gen. nov. nor with Photis . For example: P. elephantis has lateral cephalic lobe weakly extended with eyes partly enclosed in the extended lobe, and almost simple gnathopods 1 and 2; and P. trapherus has coxa 1 wider than coxa 2. However, in both species, especially the former, some structures were not described. In relation to Photis sp. E ( LeCroy, 2000) , we have examined some unpublished drawings and it belongs to Rocasphotis gen. nov. in having the same pattern of lateral cephalic lobe and eye, anteroventral margin of head, mouthparts, coxa 1 and 2, and gnathopods 1 and 2.