Pseudirona Pillai, 1964

Ravichandran, S., Vigneshwaran, P. & Rameshkumar, G., 2019, A taxonomic review of the fish parasitic isopod family Cymothoidae Leach, 1818 (Crustacea: Isopoda: Cymothooidea) of India, Zootaxa 4622 (1), pp. 1-99 : 70-72

Genus Pseudirona Pillai, 1964

Pseudirona Pillai, 1964: 220–221 .

Type species. Pseudirona laeopsi Pillai, 1964 by monotype.

Diagnosis of female. Body slightly asymmetrical, cephalon broadly triangular, with well-developed dorsally placed eyes. Peraeonites 1–3 subequal in length, peraeonite 1 antero-laterally produced into conical lobes, peraeonites 4–7 subequal in length and breadth, peraeonite 7 considerably overlapping pleon. Coxae well-developed and projecting. Pleon well immersed in peraeon, increasing in width backwards, fifth segment longest, first completely hidden by the peraeon. Peleotelson as broad as pleon, transversely oblong, distal border rounded, prominently bilobed, dorso-median carina prominent. Uropods with flattened subsimilar rami. Antenna very unequal. Mandible with three-segmented palp. Maxillula with one claw stout, maxilla with four well-curved hooks. Maxilliped foliaceous and prominently setose. Pereopods with merus and propodus in the first two pairs, and merus in all the others, internally expanded. All the appendages with fine setules or spines.

Remarks. The genus Pseudirona belongs with the group of genera that formed Lironecinae Schiöedte & Meinert’s (1884). This group includes (amongst others) the genera Mothocya Costa in Hope, 1851, Cterissa Schiöedte & Meinert, 1884 , Agarna Schiöedte & Meinert, 1884 , and Livoneca Leach, 1818 . Agarna and Cterissa are easily separated by their unusual coxal morphology and distorted body shapes (see Schiöedte & Meinert 1884; Trilles 1981; Trilles & Paperna 1980). Pseudirona is abundantly distinct from Mothocya , and in all respects except setosity and spination of the appendages agrees closely with Livoneca .

This genus has the closest resemblance to Mothocya . The general shape of the peraeon, pleon and telson is very much like that of Mothocya , but in Mothocya the peraeon is usually more asymmetrical, with the coxal plates very much so. In Mothocya the posterior coxal plates are larger than the anterior ones while they are all subsimilar in Pseudirona . In Mothocya the uropods generally overreach the telson and the rami are apically narrowed, but it is not so in Pseudirona . The extremely spiny and setose appendages are quite unlike those of any other cymothoid.