Genus Paratyphis Claus, 1879

(Figs 53–55)

Paratyphis Claus, 1879: 4 (key), 13–14.— Gerstaecker 1886: 483.— Claus 1887: 31 (key), 39.— Stebbing 1888: 1476.— Spandl 1927: 227 (key), 243.— Pirlot 1929: 157.— Barnard 1940: 541 (key).— Hurley 1955: 187 (key), 188.— Bowman & Gruner 1973: 55 (key), 55–56.— Zeidler 1978: 39 (key), 42.— Vinogradov et al. 1982: 439 (key), 448.— Shih & Chen 1995: 225 (key), 243.— Vinogradov 1999: 1200 (key), 1201.

Type species. Paratyphis maculatus Claus, 1879 by monotypy. Type material could not be found at the MFN or ZMH and is considered lost. However, the descriptions and figures of Claus (1879, 1887) readily distinguish this genus. The type locality is the South Atlantic, off the Cape of Good Hope.

Diagnosis. Head round. Eyes occupying most of head surface; grouped in two fields on each side of head. Antennae 1 of males with 1-articulate peduncle; flagellum with large, crescent-shaped callynophore, with aesthetascs arranged in two-field brush medially, with three smaller articles inserted on antero-dorsal corner. Antennae 1 of females with 2-articulate peduncle; callynophore narrowly rectangular, with two smaller articles inserted terminally. Antennae 2 of males 5-articulate; strongly zig-zagged, with all articles folded back on each other, extending anteriorly under head and posteriorly between the gnathopoda and pereopoda to pereonite 4; basal article distinctly inflated, about half or less the length of following article; articles 2 & 3 sub-equal in length; terminal two articles of similar length, about half-length preceding one; terminal article pointing anteriorly. Antennae 2 of females 5-articulate, with very small terminal article. Mandibular incisor relatively broad, straight with several teeth, with small distal lobe medially; in male orientated more or less parallel to palp. Maxillae 1 consisting of elongate plates, with four bifid teeth distally on medial margin. Maxillae 2 consisting of slightly curved plates with distinctive, rounded, medial bulge, armed with fine setae terminally. Maxilliped with inner lobes completely fused; medial margin of outer lobes with membranous fringe. Coxae 1–6 separate from pereonites; coxa 7 mostly fused with pereonite. Gnathopods 1 & 2 simple. Pereopods 3 & 4 distinctly shorter than pereopods 5 & 6. Pereopod 5; basis very broad, oval-shaped, width about 0.4–0.5 x length; articles 3–7 inserted terminally, or sub-terminally to basis. Pereopod 6; basis very broad, relatively rectangular, with straight or slightly rounded distal margin, maximum width 0.4–0.5 x maximum length, with fissure; articles 3–7 inserted sub-terminally on basis; merus with antero-distal corner slightly extended, overlapping carpus medially. Pereopod 7 reduced in size with enlarged, elongate basis; with only 1–3 terminal articles. Uropods 1 & 2 with articulated exopoda and endopoda. Uropod 3; endopod fused with peduncle. Rami of all uropoda more or less lanceolate, usually with serrated margins. Gills all without folds.

Species. Paratyphis maculatus Claus, 1879; P. pa r v u s Claus, 1887; P. promontorii Stebbing, 1888 and P. spinosus Spandl, 1924.

Sexual dimorphism. The sexes are remarkably similar in general morphology, and except for the antennae and mandibles, there is no obvious sexual dimorphism, although in some species the basis of pereopod 7 is more elongate in females.

Remarks. This genus is characterised by the simple first gnathopoda, and the poorly developed chelae of the second gnathopoda. In this respect it resembles Parascelus and Thyropus, of the family Parascelidae, in which the gnathopoda are simple. However, in Parascelus the basis of pereopod 6 is without a fissure, and in Thyropus the fissure is located well above the telsonic groove.

Paratyphis seems to be a relatively uncommon genus. Consequently very little is known about the biology of species, and there are no records of associations with gelatinous plankton. Although uncommon, it seems to be widespread in tropical and warm-temperate regions of the world’s oceans.

Species of Paratyphis are extremely difficult to determine with certainty and the genus is in need of revision. Good examples of the type species, P. maculatus, where not readily available for illustrative purposes, so P. promontorii was substituted here (Figs 53–55) because it is very similar to P. maculatus and may even prove to be synonymous. Pirlot (1930) and Vinogradov et al. (1982) recognise four species, for which the following key is provided.