Diastylis Say, 1818

Gerken, Sarah, 2014, Eleven New Species and a New Genus of Diastylidae (Crustacea: Cumacea) from Australia and One New Species from Canada, Records of the Australian Museum 66 (1), pp. 1-62 : 16

Diastylis Say, 1818

Type species. Diastylis rathkii (Krøyer, 1841) by designation.

Diagnosis. Female and subadult male. Carapace with pseudorostrum not greatly elongate. Pereopods 3–4 with or without rudimentary exopods. Telson twice length of pleonite 6, with post-anal portion, with at least 3 pairs of lateral setae. Adult male.Antennule not greatly expanded, may have brush of setae on peduncle article 3. Antennae extending to end of pleon. Pereopod and exopod bases may be weakly expanded. With 2 pairs of pleopods.

Remarks. There is currently only one species described from Australian waters that fits within the genus Diastylis . As noted in the introduction, the Australian diastylid fauna is unusual in that it is not dominated by Diastylis species. Within the Australian fauna, the genus that is most likely to be confused with Diastylis is Makrokylindrus . The telson in the only species of Makrokylindrus currently known from Australian waters is distinctly longer than the uropod peduncles, while the only species of Diastylis from this region has the telson shorter than the uropod peduncles. The difference in telson length relative to uropod peduncle length is not characteristic for the genera, but it serves to easily distinguish between the two Australian species.