Propejanice lagamarensis, Myers & Desiderato, 2019

Myers, Alan A. & Desiderato, Andrea, 2019, A new genus and species of Aoridae (Amphipoda, Senticaudata), Propejanice lagamarensis gen. nov. sp. nov. from Brazil, Zootaxa 4629 (2), pp. 287-293 : 288-290

Propejanice lagamarensis sp. nov.

( Figs 1–3 )

Type Material. Holotype male 5.0 mm (MNRJcarcino 029412) artificial rope plate, 1.5 m, on marina buoy, Antonina , Paraná, Brazil, 12.09.2017, A. Desiderato.

Other material. 5 male, paratypes MNRJcarcino 029413), same data holotype; 1 female, 1 juvenile (MN- RJcarcino 029414), artificial polyethylene plate, 1.5 m on signal buoy, Antonina , Paraná, Brazil, 04.06.2018, A. Desiderato ; 1 juvenile (MNRJcarcino 029415), artificial polyethylene plate, 1.5 m floating dock/gasoline recharge station, Cananeia , Sao Paulo, Brazil, 06.06.2018, A. Desiderato .

All data including coordinates can be found at. http://dx.doi.org/10.5883/DS-PROJLAGA

Type locality. Antonina , Paraná State, Brazil .

Etymology. Named after the Lagamar Mosaic that includes both the estuaries in which the species was found.

Description. Head. Ocular lobes obtuse; eyes of moderate size, black. Antenna 1 peduncular articles in the ratios 8:8.5:3; primary flagellum sub-equal in length with peduncle with 16 articles; accessory flagellum minute with one rudimentary fused article bearing terminal setae. Antenna 2 subpediform, a little shorter than antenna 1; peduncular article 5 a little shorter than 4, flagellum shorter than peduncular article 5, with 4 articles. Labrum ventral margin weakly convex, setose. Maxilla 1 outer plate with 10 spines; palp article 2 longer than article 1. Maxilla 2 outer plate with oblique setal row. Maxilliped outer plate extending well beyond inner plate; palp article 2 more than twice as long as article 1; article 3 much less than half as long as article 2. Mandible palp article ratios 2:6:4.5, article 3 subrectangular, with long apical and subapical setae. Labium mandibular processes moderately long, acute.

Pereon. Gnathopod 1 coxa much longer than broad, subrectangular, anterior margin rounded, unproduced; basis almost as broad as long; carpus large, subrectangular, anterior margin proximally broadly rounded, anteroproximal to midproximal margin with a single row of stridulating ridges; posterior margin weakly concave, 1.5 × as long as broad, the posterior distal margin produced into a well-developed, slender spine, propodus short, less than half length of carpus, posterior margin with distinct flange; dactylus becoming short, triangular, obtuse in large adult males. Gnathopod 2 coxa subrectangular, a little longer than broad; basis elongate, 4 × as long as broad, anterior margin substraight; merus elongate, subquadrate, diverging from carpus, with numerous, long pectinate distal setae; carpus elongate, more than 2 × as long as broad, anterior margin weakly setiferous, posterior margin with very long pectinate setae; propodus subequal in length with carpus, narrow, with weakly convex anterior and straight posterior margin, palm oblique; dactylus short, fitting palm, strongly falcate. Pereopods 3–4 coxae evenly convex anteriorally; dactylus two-thirds length of propodus. Pereopods 5–7 in the length ratios 5:7:8; pereopods 6–7 basis with long setae on the posterior margin.

Pleon. Epimera 1–3 rounded. Uropod 1 peduncle much longer than rami, with a stout, distal, inter-ramal spiniform process; inner ramus longer than outer with two marginal setae, outer ramus lacking marginal setae. Uropod 2 peduncle broad, a little longer than outer ramus, lacking an inter-ramal process; inner ramus longer than outer. Uropod 3 uniramous; peduncle subsquare, with strongly expanded flange on inner margin; ramus 2 ×length of peduncle with a small second article and several long marginal and distal setae. Telson as broad as long with nearly straight ventral margin, dorsolateral crests each with a group of 2 long setae, lateral margins each with 2 setae.

Female 5.0 mm (sexually dimorphic characters). Gnathopod 1 basis a little over 2 × as long as broad, anterior margin weakly convex; carpus subovoid, only a little longer than broad, anterior and posterior margins strongly setose; propodus about two-thirds length of carpus, subovoid, palm oblique, not clearly defined from posterior margin, which bears 3 strong robust setae; dactylus elongate, two-thirds length of propodus.

Habitat. Brackish waters between 8 and 25 psu.

Remarks. The male gnathopod 1 of P. lagamarensis closely resembles that of Grandidierella perlata Schellenberg, 1938 from Fiji. It shares with that species the presence of stridulating ridges on the anteroproximal margin of the carpus of the male gnathopod 1. It differs from that species, however, in the characteristic elongate, divergent merus of the male gnathopod 2.

When species occur as fouling in harbours historically frequented by international vessels, there is always the possibility that some species may have been transported anthropogenically. The plausibility of this explanation will only be resolved after more extensive studies along both the Brazilian and African coasts. At the moment, Propejanice gen. nov. has never been reported from any previously studied harbours anywhere in the world. The occurrence of the sibling pair Janice and Propejanice , one in the Atlantic and one in the Indian Ocean could be explained by the occurrence of an ancestor along the contiguous coastlines of what are now South America and Africa (Gondwana), 100–120 My. With the opening of the South Atlantic during the late Cretaceous, the two genera would have become isolated from one other. This latter hypothesis would be supported by the discovery of the genus in Brazil well away from man-made harbours together with failure to find the genus in Africa despite more extensive studies.

Figures

FIGURE 1. Propejanice lagamarensis sp. nov. male holotype, Antonina, Paraná, Brazil. Lateral view of male and mandible palp (Md).

FIGURE 2. Propejanice lagamarensis sp. nov. male holotype and female,Antonina, Paraná, Brazil. gnathopods (G1 & G2) and uropods (U1, U2 & U3). F = female; M = male.

FIGURE 3. Propejanice lagamarensis sp. nov. male holotype, Antonina, Paraná, Brazil. Pereopods (P3, P5, P6, P7).