Metacirolana Kussakin, 1979

Bruce, Niel L. & Rodcharoen, Eknarin, 2023, Electrolana Schädel, Hyžný & Haug, 2021 (Crustacea: Isopoda: Cirolanidae), a Junior Synonym of Cirolana Leach, 1818 and a New Species of Metacirolana Kussakin, 1978 from Cretaceous Amber of Myanmar, Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 405-412 : 408

Metacirolana Kussakin, 1979

Restricted synonymy (complete synonymy in Bruce & Rodcharoen, 2022):

Metacirolana .— Bruce, 1981: 950.— Brusca et al., 1995: 64.— Sidabalok & Bruce, 2018b: 520 .— Bruce & Rodcharoen, 2021: 680.

Type species. Cirolana japonica Hansen, 1890 ; by subsequent designation ( Kussakin, 1979).

Remarks. Bruce & Rodcharoen (2021) recently reviewed the genera of Eurydicinae (sensu Kensley & Schotte, 1989), all of which share two character states: a clypeus in the form of a ventrally or anteroventrally projecting triangular blade; and pleonites with free (not overlapped) lateral margins, notably pleonite 5 being not overlapped by pleonite 4. In some species pleonite 5 may be narrower than pleonite 4, but the posterolateral angles of pleonite 5 are visible and free rather than contained by pleonite 4. Several of these genera, notably Metacirolana and Eurydice , have a “long pleon” comprising 21–35% total body length (Bruce & Rodcharoen, 2022). Seven of the thirteen genera placed within the Eurydicinae have a posteriorly stemmed (narrowed) frontal lamina. Examination of the paratype of Electrolana madelinae which is described here as Metacirolana jimlowryi sp. nov. indicates it has these character states and unambiguously belongs to the “eurydicine” genera.

Within the “Eurydicinae”, Metacirolana jimlowryi belongs with those genera that have the posterior of the frontal lamina markedly narrowed, a “long pleon” and relatively slender ambulatory pereopods. These are Aphantolana Moore & Brusca, 2003 (see Anil & Jayaraj, 2020), Arubolana Botosaneanu & Stock, 1979 , Eurydice Leach, 1815 and Metacirolana . Eurydice differs on many generic-level character states, including antennular and antennal morphology, maxilliped with a reduced endite without coupling hooks and the uropod peduncle not produced (among other characters). The remaining three genera share a similar body shape, and all have a unique character state: maxilliped palp article 5 is quadrate or sub-quadrate. Of these three genera Aphantolana is excluded by having conate spines on the pereopods, pleonite 5 narrower than 4 and the pleotelson has strongly sinuate lateral margins. Arubolana is a strictly cave dwelling genus restricted to the Caribbean region, and is primarily distinguished by having a terminal or subterminal appendix masculina on pleopod 2, a character state not evident in the holotype of M. jimlowryi because the specimen is not adult. However, species of Arubolana can be excluded as M. jimlowryi has eyes (absent in Arubolana ), and the anterior pereopods dactyli are not longer than propodus and connate spines are absent [vs. haptorial (with a long dactylus) or with connate spines in Arubolana ]. Lastly, M. jimlowryi uniquely has a “putative autapomorphy” for Metacirolana , in antennular peduncle article 2 being longest; in all other cirolanids, antennular peduncle article 3 is the longest.