Joeropsis Koehler, 1885

Bruce, Niel L., 2015, Joeropsididae Nordenstam, 1933 (Crustacea, Isopoda, Asellota) from the Lizard Island region of the Great Barrier Reef, Queensland, Australia, ZooKeys 491, pp. 1-62 : 6-8

Taxon classification Animalia Isopoda Joeropsididae

Genus Joeropsis Koehler, 1885

Joeropsis Koehler, 1885: 7. - Kensley and Schotte 1989: 87; Wilson 1997: 86; Kussakin 1999: 12; Just 2001: 304; Kensley and Schotte 2002: 1428.

Jaeropsis . - Richardson 1905: 476; Stebbing 1905: 50.

Jaeropsis . - Vanhöffen 1914: 531(unjustified emendation). - Nordenstam 1933: 191. - Menzies and Barnard 1959: 10; Menzies 1962: 64; Menzies and Glynn 1968: 76.

Iaeropsis . - Nierstrasz 1941: 288 (unjustified emendation).

Diagnosis.

Body lateral margins parallel, with or without dorsal sculpture. Cuticle polished, smooth or finely granular. Pseudorostrum with overhanging apex. Upper lip evenly rounded, less than twice as wide as long. Mandible incisor with 5 or 6 strong subequal evenly spaced cusps; spine row setae long, in regular row, with or without lobe on right mandible spine row. Lower lip, lobes longer than wide, distally tapering, pointed. Maxillipeds endite reaching to end of or beyond palp article 3; palp about half length of endite; palp article 3 without mesial lobe, article 4 much longer than article 3. Pereopod 1 with 2 dactylar claws, pereopods 2-7 with 2 or 3 dactylar claws.

Female. Pleopod 2 (operculum) with at most a few short simple setae apically.

Type species.

Joeropsis brevicornis Koehler, 1885, by monotypy. Menzies (1962) incorrectly stated the type species to be Joeropsis curvicornis (Nicolet, 1849) as did Menzies and Glynn (1968). The original orthography on the heading page of Koehler (1885) was Joeropsis , thereafter Joeropsis [ œ] not Jaeropsis [ æ], the derivation from Jaera notwithstanding; the two spellings can be indistinguishable depending on the font used, but my interpretation is that in some cases the spelling is ambiguous. I follow the first use- Joeropsis .

Remarks.

Most older diagnoses (e.g. Menzies and Barnard 1959) contain little diagnostic information. Wilson (1997) provided the first restrictive diagnosis. Just (2001) gave the most recent generic diagnosis. A full synonymy was given by Kussakin (1999) for family and genus, though spelling changes were largely ignored, and the synonymy includes two identical spellings.

A number of authors have, over the years, recorded species of Joeropsis from widely disparate locations, some commenting on variation, occasionally establishing subspecies. In most such cases the identity of records remote from the type locality or core distribution have to be regarded with caution and scepticism. The records in the literature, particularly earlier than the 1980s, often lack adequate illustrative and descriptive data. Giving just one example, Joeropsis curvicornis (Nicolet, 1849) was recorded from Chile (original record), Sri Lanka ( Stebbing 1905) and New Zealand (when Joeropsis neozelanica Chilton, 1891 was considered a junior synonym) but these records are highly unlikely to be the one species.

Maxilliped palp article 3 in most species lacks a distomesial lobe or process, the exception being Joeropsis sanctipauli Kensley, 1989, which has a small distomesial lobe ( Kensley 1989, fig. 3H). Most species of Joeropsis , including all Australian species (those described here and by Just [2001]) have a distomesial lobe only on maxilliped palp article 2, the exception being Joeropsis mije sp. n., which also has a small distolateral lobe on palp article 1 (Fig. 15D, E).

The mandible incisor has five or six distally acute cusps, usually of similar size. Exceptions are Joeropsis indica Müller, 1991b and Joeropsis makrogenys sp. n., both of which have markedly asymmetric mandibular incisors, with a truncate mesial cusp on the left mandible with the remaining cusps set on a lobe; in Joeropsis indica the right mandible cusps are of the usual form, but in Joeropsis makrogenys the right mandible proximal or posterior cusp is conspicuously wide and broadly rounded.

Species recognition.

Species within a region are most readily identified by their characteristic colour pattern. Colour pattern is consistent, though shade and density of colour may vary, particularly on preservation. Some species will share similar colour patterns, and for old preserved specimens that have lost the colour pattern morphological characters can be used, the most obvious in the first instance being shape of the pseudorostrum. Other characters that are useful include shape of head (lateral margins narrowing anteriorly, concave, straight; serrate or not), body compactness, antenna 1 and antenna 2 (serrate or not; articles lobed or not; relative width of antenna 2 articles 5 and 6); details of the maxilliped (notably the distal margin of the endite and details of the maxilliped palp), pleotelson shape and serrations of the lateral margins; in some cases the male pleopod 1 will separate species but the differences are often subtle. Eyes are always dorsolateral in position, but vary in size and may be marginal or sub-marginal in position. A small number of species show dorsal sculpting in the form of carinae or low nodules, ventral keels may be present and the uropods may be with (most species) or without (few species) a distomesial spine. Supporting characters can be seen in body proportions and uropods. Generally the mandible is similar throughout the genus, but two species, Joeropsis indica Müller 1991b and Joeropsis makrogenys sp. n. have the proximal cusps on the left mandible incisor set on a lobe, and both species have a comparatively large labrum; additionally the mandibular incisor right proximal cusp is broadly rounded in Joeropsis makrogenys . Pereopods and pleopods are generally uniform throughout the genus, although there are differences in pereopod proportions and setation, including the number of dactylar claws on pereopods 2-7 (2 or 3 claws, and 2 claws with a stiff seta).

Sexual dimorphism.

Males and females of Joeropsis are generally similar, other than for the primary sexual characters. There are some instances of secondary sexual variation, for example the strongly dimorphic antenna 2 in Joeropsis mije sp. n. and Joeropsis minuta Müller, 1989 (see Müller 1989, fig. 15F, G), while in Joeropsis panstikta sp. n. the males have fewer spines on the pleotelson in comparison to the female.

Key to the Lizard Island species of Joeropsis

This key applies to the named species, 10 of the 15 recorded species in the region. Identifications should be checked against the remarks given for the listed but undescribed species. Inter-reef habitats beyond diving depth are highly likely to have further undescribed species.