Rocasphotis aiso, 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 : 569-575

Rocasphotis aiso sp. nov.

( Figures 4–6 )

Material examined

Holotype. Male , 3.8 mm. Atol das Rocas, Rio Grande do Norte, 3°51′21.9′′ S, 33°49′33.54′′ W, 16 October 2000, P.S. Young, P.C. Paiva and A.A. Aguiar col., 16 m, MNRJ 21607 . Paratypes. Male (dissected), Atol das Rocas, Rio Grande do Norte, 3°51′21.9′′ S, 33°49′33.54′′ W, 16 October 2000, P.S. Young, P.C. Paiva and A.A. Aguiar col., 16 m, MNRJ 21606 . Six males, Atol das Rocas, Rio Grande do Norte, 3°51′21.9′′ S, 33°49′33.54′′ W, 16 October 2000, P.S. Young, P.C. Paiva and A.A. Aguiar col., 16 m, MNRJ 21608 . Four males, Atol das Rocas, Rio Grande do Norte, Central Lagune near to Guarapirá Lagune , 15 October 2000, P.S. Young, P.C. Paiva and A.A. Aguiar col., intertidal, MNRJ 21609 .

Etymology

The species name derivates from Tupi-Guarani, a Brazilian indigenous language, aisó meaning beautiful, bonny, good looking.

Diagnosis

With characters of the genus.

Description

Head slightly shorter than two first pereonites together; 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 posterior margin without long setae; article 1 longer the article 3 (1.4 ×); article 2 subequal to article 3; primary flagellum with five articles (distal article rudimentary), with sparse aesthetascs, 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 shorter than peduncle. Epistome not produced. Upper lip entire. Mandible incisor dentate, setal row composed of robust pectinate setae (three in right and four in left); lacinia mobilis asymmetric; molar large and triturative with lateral accessory plate; palp tri-articulate; article 2 longer than article 3, anterior margin with a knob subdistally bearing three long slender setae and a row of setules, posterior margin with three long slender setae; article 3 non-spatulate, both anterior and posterior margins approximately parallel-sided with two slender setae on anterior margin and two slender setae distally. Maxilla 1 styliform, inner plate with a distal setule; outer plate slender and elongate, with seven marginal robust setae and two distal stout setae; palp bi-articulate, article 1 elongate, about 0.65 × article 2 length, article 2 curved, with four or five distal slender setae. Maxilla 2 inner plate shorter and wider than outer plate, with a row of facial setae; outer plate with a row of subdistal setae and only one distal seta. Maxilliped inner plate surpassing article 1 of palp, with two robust setae and four long setae; outer plate reaching the end of article 2 of palp, with five robust setae on inner margin and two robust setae distally; palp article 3 with a mediodistal process; article 4 without nail.

Gnathopod 1 simple, coxa longer than wide, wider than coxa 2, subequal to coxa 3–5 length, anteroventral angle with two long setae; basis widened distally, anterior margin with two long setae, posterior margin with one long seta; ischium with a long plumose seta distally; merus subequal to ischium, with five long setae distally; carpus, long, about 0.8 × propodus length, posterior margin with long setae, and two long setae on anterodistal angle; propodus with anterior and posterior margins subparallel, with a robust setae about two-thirds of posterior margin; dactylus robust, with inner margin serrate. Gnathopod 2 simple, coxa longer than wide, subequal to coxa 1 length; basis inflated, widened distally, with two long setae on posterior margin; ischium shorter than merus; merus about 0.8 × carpus length, with long setae on anterodistal margin; carpus, long, subequal to propodus, anterodistal angle with two long setae, posterior margin with five long setae; propodus with anterior and posterior margins subparallel, posterior margin with two tufts of long setae; dactylus robust, with inner margin serrate. Pereopod 3 coxa longer than wide, widened distally, with three setae on distal margin; basis ovate, posterior margin with five long simple setae about halfway, and three plumose setae near posterodistal angle; ischium short, subequal to carpus, with two setae on posterior margin; merus shorter than carpus and propodus together, with anterior margin produced; carpus with two setae on posterodistal angle; propodus anterior margin with one seta, posterior margin with two setae; dactylus robust and about two-thirds of propodus length. Pereopod 4 coxa longer than wide, rounded distally, with three setae on distal margin; basis ovate, anterior margin with one long simple seta, posterior margin with two long simple setae and two long plumose setae; ischium short, subequal to carpus, posterior margin with two plumose setae; merus shorter than carpus and propodus together, with anterior margin produced, with dense plumose setae; carpus posterodistal margin with long simple setae; propodus with two tufts of setae on anterior margin and one on anterodistal angle, posterior margin with tow setae; dactylus robust and about one-third of propodus length. Pereopod 5 coxa longer than wide, with large anterior lobe; basis ovate, with sparse setae on both anterior and posterior margin; merus rectangular, subequal to carpus; carpus rectangular 1.2 × longer than wide, with a tuft of setae on both anterodistal and posterodistal angles; propodus slender, posterior margin with one middle robust setae and two subdistal robust setae; dactylus directed posteriorly, with a subdistal corona of cuticular spines. Pereopod 6 strongly enlarged, subequal to body length, coxa short, wider than long; basis ovate, with two setae on anterior margin; ischium shorter than carpus, with a posterior process; merus longer than carpus and propodus together, very inflated, with a posteroproximal angle produced, and posterodistal angle produced in a bifid process reaching halfway of carpus length; carpus about two-thirds of propodus length, 1.5 × longer than wide, with one tuft of setae on both anterodistal and posterodistal angles; propodus slender, anterodistal angle with five setae, posterior margin with three setae and one robust seta and two slender setae on posterodistal angle; dactylus directed posteriorly, about 0.5 × propodus length, with two spines on posterior margin. Pereopod 7 coxa short, wider than long; basis ovate, with two facial setae near posterior margin, posterodistal angle produced in short spine; ischium anterodistal angle with one seta, posterior margin with a short triangular process; merus rectangular, longer than carpus; carpus with two setae on both anterodistal and posterodistal angles; propodus slender, anterior margin with a tuft of setae, anterodistal angle with long setae, posterior margin with three setae and one robust seta on posterodistal angle; dactylus directed posteriorly, with a subdistal corona of cuticular spines.

Epimera 1–3 rounded. Uropod 1 peduncle longer than rami (1.5 ×), outer margin with four robust setae; distoventral margin with a corona of cuticular spines; both rami with two apical setae, outer ramus with one marginal seta. Uropod 2 peduncle 1.4 × of inner ramus length, with one robust seta on both inner and outer distal angles; both rami with one middle seta, inner ramus subequal to outer ramus length, with two apical robust setae; outer ramus with three apical robust setae. Uropod 3 peduncle longer than outer ramus, with a rounded basoproximal lobe; inner ramus naked, about 0.2 × outer ramus length; outer ramus bi-articulate, article 1 with two distal setae; article 2 about 0.1 × article 1 length, with one distal seta. Telson triangular, distal margin subacute, with two setae on lateral margins, two pairs dorsal setae, and with a small knob on either side.

Female

Unknown.

Remarks

As noted previously, Rocasphotis aiso sp. nov. shares with P. elephantis Barnard, 1952 , P. trapherus Thomas and Barnard, 1991 and Photis sp. E ( LeCroy, 2000) a strongly enlarged pereopod 6 of adult males. Apart from generic-level differences, R. aiso sp. nov. differs from these species by the following combination of characters: basis of pereopod 6 rounded posteriorly, lacking an acute process on the posterior margin and with a bifid process extending to halfway of merus, and pereopod 7 not having an acute process on posterior margin. Moreover, it differs from Photis sp. E ( LeCroy, 2000) in having two distal stout setae on outer plate of maxilla 1, instead three.

Geographical distribution

Known only from the type locality, Atol das Rocas, Brazil .

Key to genera of family Photidae

1. Uropod 3 uniramous........................................... 2 Uropod 3 biramous............................................ 4

2. Coxa 1 with anteroventral angle not produced forward.......................................................... Papuaphotis Myers, 1995 Coxa 1 with anteroventral angle produced.......................... 3

3. Lateral cephalic lobes strongly extended and longer than peduncular article 1 of antenna 1........................................................................................ Ampeslisciphotis Pirlot, 1938 Lateral cephalic lobes moderately extended, shorter than peduncular article 1 of antenna 1............................................................................................ Microphotis Ruffo, 1952

4. Lower lip, outer lobe with a distal notch (Ampithoe- like)................................................... Falcigammaropsis Myers, 1995 Lower lip, outer lobe lacking distal notch........................... 5

5. Antenna 2 flagellum paddle-shaped.......................................................................... Audulla Chevreux, 1901 Antenna 2 flagellum not paddle-shaped............................ 6

6. Gnathopods 1 and 2 subchelate and similar; sexual dimorphism weak; coxae 1–5 as broad or broader than long.......................................................................... Graciliphotis Myers, 2009 Gnathopods 1 and 2 subchelate and dissimilar, or simple; sexual dimorphism strong; coxae 1–5 longer than wide................................ 7

7. Maxilla 2 inner plate without a row of facial setae............................................................ Dodophotis Karaman, 1985 Maxilla 2 inner plate with a row of facial setae....................... 8

8. Uropod 3 inner ramus very reduced, equal or shorter than one-third of outer ramus....................................................... 9 Uropod 3 inner ramus not reduced, subequal to outer ramus.......... 10

9. Lateral cephalic lobes weakly extended, eye poorly developed and partially enclosed in the lobe; maxilla 1 styliform, outer plate slender with two or three stout setae distally and seven robust setae extending down to medial margin, palp article 1 elongate; uropod 1 peduncle with distoventral corona of cuticular spines........................................................................................... Rocasphotis gen. nov. Lateral cephalic lobes moderately extended, eye if present totally enclosed in the lobe; maxilla 1 not styliform, outer plate slender even robust setae along distal margin, palp article 1 not elongate; uropod 1 peduncle with a poorly developed or absent inter-ramal process.......................................................................... Photis Krøyer, 1842

10. Uropod 3 outer ramus uni-articulate........................................................................ Posophotis Barnard, 1979 Uropod 3 outer ramus bi-articulate, second article rudimentary........ 11

11. Male coxa 2 distinctly longer than the coxae 1 and 3–5....................................................... Megamphopus Norman 1869 Male coxa 2 subequal to coxae 1 and 3–5.......................... 12

12. Article 3 of mandibular palp parallel-sided; pereopods basis weakly expanded............................................................................................ Virgammaropsis Myers, 2009 Article 3 of mandibular palp spatulate, widened distally; pereopods basis expanded pereopod........................................... 13

13. Head with anteroventral margin strongly recessed; uropod 3 peduncle short and broad, rami short and stout........................................................................ Latigammaropsis Myers, 2009 Head with anteroventral margin weakly recessed; uropod 3 peduncle and rami relatively elongate................................................................................ Gammaropsis Liljeborg, 1855

Figures

Figure 4. Rocasphotis aiso gen. nov. et sp. nov., paratype, male, 3.7 mm, Atol das Rocas, Rio Grande do Norte, MNRJ 21606. Scale bars = 0.05 mm.

Figure 5. Rocasphotis aiso gen. nov. et sp. nov., paratype, male, 3.7 mm, Atol das Rocas, Rio Grande do Norte, MNRJ 21606. Scale bars = 0.1 mm.

Figure 6. Rocasphotis aiso gen. nov. et sp. nov., paratype, male, 3.7 mm, Atol das Rocas, Rio Grande do Norte, MNRJ 21606. Scale bars = 0.1 mm.