Photis sarae, 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 : 562-567

Photis sarae sp. nov.

( Figures 1–3 )

Type material

Holotype, male, 2.8 mm, Urca Beach, Rio de Janeiro, P.C. Paiva and M.C. Rayol col., 1–2 m, 11 June 1997, MNRJ 21572 . Paratypes. Male, 3.4 mm, Urca Beach , Rio de Janeiro, P.C. Paiva and M.C. Rayol col., 1–2 m, 11 June 1997, MNRJ 21573 , (dissected) . Female, 3.6 mm, Urca Beach , Rio de Janeiro, P.C. Paiva and M.C. Rayol col., 1–2 m, 11 June 1997, MNRJ 21574 , (dissected) . Male immature, Urca Beach , Rio de Janeiro, P.C. Paiva and M.C. Rayol col., 1–2 m, 11 June 1997, MNRJ 21575 , (dissected) . 28 males and 46 females, Urca Beach , Rio de Janeiro, P.C. Paiva and M.C. Rayol col., 11 June 1997, 1– 2 m, MNRJ 21576 . Female, Jurujuba Beach , Rio de Janeiro, E. Omena col., intertidal, 20 October 2006, MNRJ 21610 . Female, Jurujuba Beach , Rio de Janeiro, E. Omena col., intertidal, 15 September 2005, MNRJ 216111 . Female, Paquetá Beach , Rio de Janeiro, E. Omena col., intertidal, 20 October 2006, MNRJ 216112 . Male, Flamengo Beach , Rio de Janeiro, E. Omena col., intertidal, 20 October 2006, MNRJ 216113 .

Etymology

Photis sarae sp. nov. is named in honour of Dr Sarah E. LeCroy (University of Southern Mississippi) in recognition of her contribution to amphipod taxonomy.

Diagnosis

Antenna 1 posterior margin with sparse long setae. Lateral cephalic lobe extended and rounded distally; eyes, ovate and partly enclosed in extended lobe. Coxae 1–4, distal margins not lined with long setae. Coxa 1 anterodistal angle with one long seta. Coxae 3–4 distal margin with stridulating ridges. Gnathopod 2 carpus with welldeveloped anteromedial setose process; propodus ovate, palm acute, extending almost entire posterior margin, with one proximal subacute process followed by an excavation leading to a straight portion, palmar corner defined by medioproximal subacute process; dactylus not reaching end of palm. Pereopods 5–7 dactyli with accessory spine. Uropod 3 inner ramus about 0.2 × outer ramus length, with one apical seta. Telson distal margin concave.

Description

Head slightly longer than two first pereonites together; lateral cephalic lobe produced and rounded distally; eyes, ovate and large occupying almost all lateral cephalic lobe, antennal sinus moderately recessed. Antenna 1 posterior margin with sparse long setae; article 1 subequal to article 3; article 2 about 1.5 × length of article 3; primary flagellum with eight articles (distal article rudimentary), shorter than peduncle, accessory flagellum absent. Antenna 2 subequal to antenna 1, posterior margin with sparse long setae; article 4 longer than article 5; flagellum with six articles and shorter than peduncle. Epistome acute and curved upwards. Upper lip incised distally. Mandible incisor dentate, setal row composed of robust pectinate setae with tuft of plumose setae near basis of molar; molar triturative with accessory lateral plate and a long plumose seta and three marginal slender setae; palp tri-articulate; article 2 longer than article 3 with marginal plumose setae; article 3 spatulate, anterior and posterior margins subsymmetrical, distally flattened, with long marginal and distal setae, being mostly distal. Maxilla 1 inner plate naked; outer plate with eight robust setae; palp 2 articulate, article 2 with five distal robust setae and two facial setae. Maxilla 2 inner plate shorter than outer plate, with a row of facial setae. Maxilliped inner plate with four robust setae and eight plumose setae; outer plate reaching about two-thirds of article 2 palp, with four robust setae on inner margin and three robust setae distally; palp article 4 with a nail.

Gnathopod 1 subchelate, coxa 1 longer than wide and shorter than coxa 3–5, anteroventral angle with a long seta; basis moderately robust with three plumose long setae on both anterior and posterior margins; ischium with seven long setae distally; merus longer than ischium, with plumose long setae on posterior margin; carpus about 1.3 × propodus length, with long setae along posterior margin, and three long setae on anterodistal angle; propodus ovate, palm acute, evenly rounded and serrate, extending almost to entire posterior margin, with two cuspidate setae, one near hinge of dactylus and another halfway of palm, also with long facial setae; dactylus fitting palm, inner margin serrate, with three spines. Gnathopod 2 subchelate, coxa 2 longer than wide, subequal to coxa 1 and shorter than coxae 3–5; basis moderately robust, widened distally, with two long setae on posterior margin, anterodistal angle produced into a well-developed rounded lobe, with marginal stridulating ridges; ischium subequal to merus, with anteromedial margin produced into a rounded lobe; merus with 16 simple distal setae; carpus triangular and complex sculptured, with well-developed anteromedial setose process, posterodistal angle produced into a well-developed rounded lobe, distal margin of lobe with five setae; propodus ovate, inner face with long simple setae, palm acute, extending to almost entire posterior margin, with one subacute process near hinge of dactylus followed by an excavation leading to a straight portion, palmar corner defined by a medioproximal subacute process; dactylus with six spines on inner margin, not reaching end of palm. Pereopod 3 coxa longer than wide, widened distally, with stridulating ridges along distal margin; basis rectangular, anterior margin with one long simple seta and one subdistal plumose seta, posterior margin with four middle simple setae, and four long plumose setae on subdistal to posterodistal angle; ischium short, subequal to carpus, with two setae on posterior margin; merus shorter than carpus and propodus together, with anterior margin produced, with three long plumose setae and four distal long simple setae, posterior margin with three simple setae; carpus with three simple setae on anterodistal angle and four simple setae on posterior margin; propodus with two tufts of setae on anterior margin and some setules along posterior margin. Pereopod 4 coxa longer than wide, both anterior and posterior margins subparallel to each other, with stridulating ridges along distal margin; basis rectangular, anterior margin with one long simple seta and three subdistal plumose setae, posterior margin with three middle long simple setae, and eight long plumose setae on subdistal to posterodistal angle; ischium short, subequal to carpus; merus shorter than carpus and propodus together, with anterior margin produced, with two distal long simple setae, posterior margin with three simple setae; carpus with two setules on posterodistal angle; propodus with two tufts of setae on anterior margin and some setules along posterior margin. Pereopod 5 coxa as long as wide, with large anterior lobe; basis ovate, with sparse setae on both anterior and posterior margins; merus rectangular, slightly shorter than carpus; carpus with a tuft of setae on posterodistal angle; propodus slender, posterior margin with one middle robust seta and two distal robust setae; dactylus directed anteriorly, with one accessory spine. Pereopod 6 shorter than pereopod 7, coxa short, wider than long; basis ovate, with sparse setae on both anterior and posterior margins; merus rectangular, longer than carpus, with a long seta on posterodistal angle; carpus with a tuft of setae on posterodistal angle; propodus slender, longer than merus, posterior margin with one halfway robust setae and two distal robust setae; dactylus directed anteriorly, with one accessory spine. Pereopod 7 coxa short, wider than long; basis ovate, with sparse setae on both anterior and posterior margins; merus rectangular, longer than carpus, with a long seta on posterodistal angle; carpus anterodistal angle with two long setae, with a tuft of setae on posterodistal angle; propodus slender, longer than merus, anterior margin with three sparse setae and two distal robust setae, posterior margin with two setae; dactylus directed posteriorly, with one accessory spine.

Epimera 1–3 rounded. Uropod 1 peduncle longer than rami (1.5 ×), outer margin with five robust setae, outer margin with one distal robust seta; inter-ramal process acute, 0.1 × peduncle length; both rami with apical seta, inner ramus with two marginal setae. Uropod 2 peduncle 1.2 × inner ramus length, with one robust seta on both inner and outer distal angles; inter-ramal process acute, 0.09 × peduncle length; both rami with apical and middle setae, inner ramus 0.75 × outer ramus length. Uropod 3 peduncle longer than outer ramus, with three marginal setae; inner ramus about 0.2 × outer ramus length, with one apical seta; outer ramus bi-articulate, article 1 with one distal seta; article 2 about 0.15 × article 2 length, with two distal long setae. Telson trapezoidal, distal margin concave, with two pappose setae on each lateral margin, with one pappose seta on each distolateral margin, and two long setae on distodorsal margin.

Female ( paratype, 3.6 mm, MNRJ 21574 )

Differs from male by gnathopod 2, where basis lacks a process on anterodistal angle; ischium rectangular, with anteromedial margin not produced; merus with 10 long setae on posterior margin; carpus triangular shaped, but no complex sculpture, posterodistal angle rounded, without anteromedial process; propodus ovate, palm not extremely acute and subequal to posterior margin, with a subacute process near hinge of dactylus followed by a “U” excavation leading to a tridentate process bearing a robust seta, palmar corner is defined by an acute spine; dactylus reaching end of the palm and inner margin has three spines.

Immature male ( paratype, 2.7 mm, MNRJ 21575 )

Differs from mature male in having ischium of gnathopod 2 with anteromedial margin poorly produced and palm subequal to posterior margin, with one subacute process followed by a sinuous, palmar corner defined by a subacute process (not displaced to medial margin).

Remarks

From the almost 60 species of Photis known, P. sarae sp. nov. is most closely related to Photis hawaiensis Barnard, 1955 , from the Hawaiian Islands, and Photis sp. F ( LeCroy, 2000) , from Biscayne Bay, Florida, in having subacute lateral cephalic lobe, coxae 3–4 with stridulating ridges on distal margin, carpus of gnathopod 2 with anteromedial setose process, palm of mature male occupying almost entire posterior margin and palmar corner defined by medioproximal subacute process. Nevertheless, P. sarae sp. nov. can be distinguished from both species by the following combination of characters: gnathopod 2 basis with two long setae on posterior margin, palm with only one spine (excluding palmar corner); pereopod 3 anterior margin of merus with long plumose and simple setae; dactyli of pereopods 5–7 with accessory spine (pereopod 5 in P. hawaiensis and pereopods 5–6 in Photis sp. F ); inner ramus of uropod 1 with two robust setae; inner ramus of uropod 3 about one-quarter of outer ramus length, and telson trapezoidal with distal margin concave, compared with triangular with acute or subactute tip in P. hawaiensis and Photis sp. F , respectively. Also, females of P. sarae sp. nov. differ from P. hawaiensis in having a tridentate process near palmar corner of gnathopod 2, and in lacking a serrate portion after palmar corner.

Geographical distribution

Guanabara Bay, Rio de Janeiro, Brazil.

Figures

Figure 1. Photis sarae sp. nov., holotype, male, 2.8 mm, Urca Beach, Rio de Janeiro, MNRJ 21572. Scale bars = 0.1 mm.

Figure 2. Photis sarae sp. nov., holotype, male, 2.8 mm, Urca Beach, Rio de Janeiro, MNRJ 21572. Immature male, 3.4 mm, paratype, Urca Beach, Rio de Janeiro, MNRJ 21573. Female, 3.6 mm, Urca Beach, Rio de Janeiro, MNRJ 21574. Scale bars = 0.1 mm.

Figure 3. Photis sarae sp. nov., holotype, male, 2.8 mm, Urca Beach, Rio de Janeiro, MNRJ 21572. Scale bars, T = 0.05 mm, for remains = 0.1 mm.