Stegosoladidus complex, Berge, 2001

Berge, JØrgen, 2001, Revision of Stegosoladidus Barnard and Karaman, 1987 (Crustacea: Amphipoda: Stegocephalidae), redescription of two species and description of three new species, Journal of Natural History 35 (4), pp. 539-571 : 558-562

Stegosoladidus complex n. sp.

(®gures 18±20)

H OLOTYPE. Female, J24060 (Victoria), 38ss17.70¾S, 149ss11.30¾E, 400 m.

PARATYPES.Forty-nine specimens, J24060 .

Additional material. J24053 , seven specimens, 37ss0.60¾S, 150ss20.70¾E, 363 m ; J45336 , two specimens, 38ss52.6¾S, 148ss25.2¾E, 130 m.

Distribution. Known from Victoria, New South Wales and Tasmania.

Description. Rostrum very small.

Antennae short. Antenna 1 longer than antenna 2, ¯agellum four-articulate, accessory ¯agellum with two articles. Antenna 2 peduncle (articles 3±5) longer than ¯agellum, article 3 short, about as long as broad; article 4 longer than article 5.

Epistome produced laterally, rectangular, with a long ridge on each side; epistomal plate (medial keel) produced into a small elongate medial ridge covering the entire epistome.

Mandible incisor transverse, smooth, left lacinia mobilis present, reduced, laterally straight, conical.

Maxilla 1 palp uni-articulate, rectangular, apex not reaching above the apex of outer plate; outer plate distally rounded, ST in a pseudocrown, ST ®rst row with ®ve setae, ST 1 ordinary (similar to ST 2±4), ST 1±5 reduced, four setae present, ST 6 absent, gap between ST 5 and ST 7, ST A present, located distally, part of ®rst row, ST B absent, ST C present; inner plate without a well developed shoulder, setae pappose.

Maxilla 2 ordinary, outer plate setae without distal hooks or cleft; inner plate setae row A covering the entire margin, appressed to row B, row A setae pappose, three or four ®rst setae diOEerentiated from the other setae (weakly pappopectinate); row B setae proximally simple, distally without cusps; row C absent; row D absent.

Maxilliped palp four-articulate, article 2 distally unproduced, articles 1±3 inner margins without plumose setae, dactylus distally simple (pointed); inner plate not exceeding base of palp article 2; no nodular setae; medial setae row absent; distal setae row present, setae simple; inner setae row absent; outer plate outer setae row present, marginal, setae attached normally, long robust, straight; inner setae row absent; distal setae-group absent.

Labrum very short; lobes symmetrical, both lobes reduced.

Labium distally broad, oval.

Coxal plates and basis on the pereopods smooth. Coxae 1±3 contiguous.

Pereopod 1 coxal plate not as deep as basis, propodus subovate.

Pereopod 2 longer and thinner than pereopod 1, ischium elongate, ratio length 5 breadth exceeding 1.5, ischium distal posterior margin with plumose setae, propodus subrectangular, palm absent.

Pereopod 4 coxa posteroventral lobe large, reaching about the base of pereon segment 7; basis anterior and posterior margins without long setae, plumose setae on distal anterior and posterior margins, ischium with plumose setae on posterior distal margin.

Pereopod 6 basis posteriorly expanded, expansion conspicuous, rounded posteriorly, with a row of long plumose setae.

Pereopod 7 basis anterior margin straight, distally rounded, medial row of setae present, setae short and robust, carpus present, dactylus present.

Oostegites on pereopod 2±5, gills on pereopod 2±7.

Pleonites 1±3 dorsally smooth.

Urosomites 2 and 3 free. Uropod 1 peduncle longer than rami, outer ramus longer than inner. Uropod 2 peduncle longer than rami, outer ramus as long as inner. Uropod 3 peduncle longer than half the length of rami, outer ramus two-articulate, outer ramus longer than inner.

Telson as long as broad, as long as peduncle uropod 3, cleft, apically rounded, submarginal setae on apex of each lobe.

Males: pereopod 2 propodus equally sized in males and females, urosome ordinary (similar to females), uropods 1±3 with ordinary outer ramus.

Etymology. The species name refers to its more`complex’ appearance than that of S. simplex , in that articulations are present both between maxilliped palp articles 1 and 2, and between urosome segments 2 and 3. Although the name complex is not grammatically correct, it is chosen to accommodate the dualism between its very close relationship with S. simplex and at the same time the more`complex’ morphology.

Remarks. The present species is very closely related to S. simplex , but is separated on the presence of articulations between maxilliped palp article 1 and 2, and between urosome segments 2 and 3.