Metopoides rotundus (Stebbing, 1917)

Krapp-Schickel, Traudl, 2011, On the Austral-Antarctic stenothoids Proboloides, Metopoides, Torometopa and Scaphodactylus (Crustacea Amphipoda) Part 2: the genus Proboloides, with description of two new genera and the transfer of two nominal species to Metopoides, ZooKeys 86, pp. 11-45 : 21-23

Metopoides rotundus (Stebbing, 1917) Fig. 5

Metopa rotunda Stebbing, 1917: 39-40, pl. XCVIB; K.H. Barnard 1940: 444; Griffiths 1974: 326

? Proboloides stephenseni Ruffo, 1949: 15, fig. 1 (12-18), fig. 2 (1-5), fig. 3 (1)

? Torometopa stephenseni Barnard & Karaman, 1991: 700

Proboloides rotundus Barnard & Karaman, 1991: 696

Material examined.

Type material of Proboloides stephenseni MNVCr.

Redescription:

Body

smooth. Eyes rounded, large.

Length.

Male 3,5 mm.

Antennae.

A1 = A2, A1 less than half of body length, peduncle robust, art 1 length about three times the width; acc. flag. with 2 arts, flagellum 12 arts. A2 subequal in length to A1, peduncle robust, art 4 ≥ art 5, flagellum about as long as peduncle art 5, with 9 arts.

Mouthparts.

Md palp with 3 arts, art 1 and art 3 subequal, art 3 longer than 1/3 art 2, with 2 long distal setae. Mx 1 palp with 2 arts. Mxp IP separated, OP longer than half ischium; dactylus as long as propodus.

Coxae.

Cx2 with rounded anterior margin, straight posterior one, angle rounded with small tooth; Cx3 with parallel margins, Cx4 not excavated, anterior and posterior margin rounded, about as long as wide.

Gnathopods.

Gn1, 2 propodi similar in shape, different in size. Gn1 dactylus ordinary; propodus triangular, palm well defined, about twice as long as wide, about as long as hind margin; carpus shorter than propodus, trapezoid, longer than wide, with parallel margins; merus with very short distal free margin. Gn2 length of propodus = Cx2; propodus more than twice the size of propodus Gn1; hind margin much shorter than length of palm which has shallow incisions and crenulations, palmar corner well defined by small tooth-shaped prolongation but no U-shaped incision. Dactylus shorter than palm. Gn2 carpus shorter than wide, cup-shaped, merus not lobate.

Peraeopods.

P5 dactylus half length of slim propodus; merus posterodistal margin not reaching half of carpus length, basis rectolinear, width proximally and distally subequal, posterodistally rounded, but not lobed. P6, 7 similar, basis hind margin rounded, merus posterodistal corner shortly lengthened and somewhat widened, not reaching to half of carpus length.

Epimeral plates.

Ep3 posterodistal corner rectangular, but rounded.

Uropods.

U3 peduncle shorter than ramus, art 1 of ramus longer than art 2; peduncle with one short robust seta distally, ramus art 1 with 2 robust setae.

Telson

not reaching end of peduncle U3; less than twice as long as wide; distally pointed, marginally two robust setae.

Sexual differences.

Females unknown.

Distribution.

Antarctica, 70°23'0"S, 82°47'0"W ( Proboloides stephenseni Ruffo, 1949). South Africa ( Proboloides rotunda Stebbing, 1917).

Depth.

42 fathoms = 76,8 m ( Proboloides rotunda , Stebbing 1917: 40)

After Barnard and Karaman (1991: 696) the genus Proboloides has its distribution in the Atlantic Ocean, S-Africa and the Antarctica. Therefore it was important to check also non-Antarctic species.