Synidotea Harger, 1878

Poore, Gary C. B., 2012, Four new valviferan isopods from diverse tropical Australian habitats (Crustacea: Isopoda: Holognathidae and Idoteidae), Memoirs of Museum Victoria 69, pp. 327-340 : 329-332

Synidotea Harger, 1878

Synidotea Harger, 1878: 374 . – Poore and Lew Ton, 1993: 261–

262.

Remarks. The valviferan idoteid genus Synidotea occurs worldwide and is represented by 59 species, most highly endemic ( Schotte et al., 2008 onwards). Chapman and Carlton (1991, 1994) suggested that some described species are in fact a single one, the Japanese Synidotea laevidorsalis Miers, 1881 translocated elsewhere, especially to ports. This assertion was disputed by Poore (1996) who showed that morphological and ecological differences could be shown between several examples. Nevertheless, one other species does appear to be translocated. Synidotea laticauda Benedict, 1897 , first described from the estuarine parts of San Francisco Bay, is now known, though wrongly identified, from the Gironde Estuary, France ( Mees and Fockedey, 1993), the Guadalquivir River estuary, Spain ( Cuesta et al., 1996) and Delaware Bay, USA ( Buschek and Boyd, 2006).

Most idoteid genera are restricted to temperate shores but Synidotea is not ( Schotte et al., 1995 onwards). Northern Australia is within the broad Indo-West Pacific biogeographic region and species recorded there could potentially occur in the Australian tropics. Four species have been described from India: S. variegata Collinge, 1917 , S. fluviatilis Pillai, 1954 , S. worliensis Joshi and Bal, 1959 and S. hanumantharaoi Kumari and Shyamasundari, 1984 . Two, S. fecunda Javed and Yasmeen, 1994 and S. indica Javed and Yasmeen, 1994 occur in Pakistan and S. poorei Cai and Teo, 2012 in Singapore. Further afield, S. oahu Moore, 2004 was described from Hawaii and S. pacifica Nobili, 1906 from Tuamoto. All of these belong to the so-called S. hirtipes Milne Edwards, 1840 group of species; S. hirtipes is from southern Africa. Both new species differ from the Indian Ocean species as follows: from S. hirtipes in the absence of ridges on the uropod (Kensley, 1978), from S. fecunda in the absence of bosses on the head, from S. indica in the less angled pereonite margins, from S. variegata in the more robust antenna 2 and less obviously triangular uropodal endopod, and from S. hanumantharaoi and S. worliensis in the more elongate antenna 2. The new species differ from S. poorei in absence of or less dense persistent colour and more elongate antenna 2.

The four Australian species already described are temperate: S. grisea Poore and Lew Ton, 1993 and S. keablei Poore and Lew Ton, 1993 from southeastern states, S. watsonae Poore and Lew Ton, 1993 from southern WA and Vic., and an undescribed species from WA. Of these, the new species differ from S. grisea and S. keablei most obviously in the broader pleotelsonic apex, and from S. watsonae in the absence of sculpture. The two species differ from each other most obviously in colour, proportions of the articles of antenna 2, pereopods and uropodal endopod.