Cryosignum (Just & Wilson, 2007)

Just, Jean & Wilson, George D. F., 2021, Redescriptions and new species in the ‘ Austrosignum-Munnogonium’ complex sensu Just & Wilson (2007), mainly from the Southern Hemisphere (Crustacea Isopoda: Paramunnidae), Zootaxa 4952 (3), pp. 401-447 : 416-417

Cryosignum sp.

( Fig. 9 )

Austrosignum grande Hodgson, 1910 .— Menzies, 1962: 52, fig. 11.

‘ Cryosignum’ undescribed species.— Just & Wilson, 2007: 14.

Material examined. Male , 1.3 mm, Southern Chile, Seno Reloncavi, off Puerta Montt, 41°30’15’’S, 72°57’50’’W, 35 m, coarse sand, 14 July 1949, stn M142, SMNH Gen coll. 155406 (single specimen reported by Menzies, 1962.)

We do not name this mature, but probably not fully terminal, male. It was collected in the vicinity of the type locality of Cryosignum latifrons (above), only a few month later. There is thus a possibility that the specimen could be the so far unknown male of that species, although it differs from the female in the shape of the lateral margins of pereionites 2–4. While that could be an expression of sexual dimorphism, the issue cannot be resolved until the sexes are collected together.

We refer the specimen to Cryosignum on account of presence of a mandible palp (observed but not illustrated), an oval pereiopod I carpus, 2 robust setae on pereiopod I propodus, smooth pleotelson margins, and a straight, api- cally truncate uropodal endopod. This combination of characters distinguishes Cryosignum from other genera in the Austrosignum – Munnogonium complex.

Menzies (1962, fig.11) illustrated this specimen with the caption (part) “…A, holotype male in toto.” That statement was clearly an unintended error.

Remarks. In their study of the isopod fauna of the South Atlantic Tristan da Cunha Archipelago Sievertsen and Holthuis (1980) reported the presence of a single male of Paramunna antarctica (Richardson, 1906) from Stoltenhoff island, (37°25’S, 12°30’W, 30–45 m). Just & Wilson (2004, table 1) revived Richardson’s original genus Austrimunna for the species Austrimunna antarctica Richardson, 1906 . However, Richardson’s species is part of the Paramunna complex ( Just & Wilson 2004) and not he Austrosignum - Munnogonium complex under consideration here. The specimen shown by Sievertsen & Holthuis (fig. 27) is a species of Cryosignum , similar to Cryosignum sp. of this paper, but because of lack of detailed description by Sievertsen and Holthuis and differences in rendition between Sievertsen and Holthuis’ and our illustrations we cannot be certain they belong to the same species.

Figures

FIGURE 9. Cryosignum sp., ♂. p1, pereiopod I; pl1, pleopod I; up, uropod. Scale for habitus, 0.5 mm.