Joryma Bowman & Tareen, 1983

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 : 28-29

Genus Joryma Bowman & Tareen, 1983

Joryma Bowman & Tareen, 1983: 21–25 .— Aneesh, Helna, Trilles & Chandra, 2018b: 4.

Agama Schiöedte & Meinert 1884: 328–329 [partim].— Barnard 1936: 169.— Pillai 1954: 16; 1964: 211.

Type species. Joryma sawayah Bowman & Tareen, 1983 .

Provisional diagnosis of female. Bowman & Tareen (1983) provided the following diagnosis for the genus Joryma ; the principal characters are: Body asymmetrical, twisted to one side, widest at pereonite 5. Cephalon as long as wide, anterior margin rounded, deeply impressed pereonite 1. Pereonite 1 anterolateral expansion unilateral and not bilobed, not reaching the anterior margin of cephalon. Coxae 2 and 3 inflated, much larger than remaining coxae; coxa 4 and 5 may be inflated. Pleon nearly as wide as pereon; pereonite 1 partly or completely covered by pereonite 7. Antennula well separated at bases. Mandibular palp enlarged, very stout, indistinctly or non-segmented.

Remarks. Joryma is readily identified by the cephalon being immersed in pereonite 1; pereonite 1 produced on each side into inflated bilobed process reaching well beyond anterior margin of cephalon; cephalon anterolateral margins convex; antennula well separated at bases; pleopods rami lamellar, endopod smaller than exopod; protopod without coupling hooks and expanded laterally into rounded lobes.

Bowman & Tareen (1983) discovered the genus Joryma from Kuwait. Bowman & Tareen (1983) grouped four species under the genus Joryma , Agarna engraulidis Barnard, (1936) , Agarna tartoor Pillai, 1954 , Agarna brachysoma Pillai, 1964 and Joryma sawayah Bowman & Tareen, 1983 . Taking into consideration the fact that the important generic feature of Agarna is the hunched asymmetrical pereon with posterior pereonites flattened and expanded laterally on one side a character not observed in the genus Joryma and also the consonance between the Agarna and the generic diagnosis of Joryma differed. More recently, Rameshkumar et al. (2011) and Aneesh et al. (2018b) described two new species Joryma hilsae Rameshkumar et al. 2011 and Joryma malabaricus Aneesh et al. 2018 from India respectively. The differences between these five species delineated in Table 1 of Rameshkumar et al. (2011).

Other related branchial-attaching genera differ from Joryma in the following characteristics: Elthusa Schiöedte & Meinert, 1884 pleon moderately to deeply immersed into pereonite 7, usually wide (greater than 0.5 widths of pereon); pleonite 1 as wide, or only a little narrower than 2 ( Bruce 1990); Livoneca Leach, 1818 Cephalon anterior margin folded back, but not projecting between antennal bases; pleonites becoming progressively narrower towards posterior; ventrolateral margin of pleonites 1 and 2 or 1–3 weakly bilobed ( Bruce 1990).

Species of Joryma are restricted mainly to clupeiform hosts, with the exception of Joryma sawayah Bowman & Tareen, 1983 known from the perciform fish Terapon puta ( Terapontidae ). Joryma species show different levels of host specificity towards clupeiform fishes. Four species of Joryma , including the new species, are only known from the type host; Joryma engraulidis ( Barnard, 1936) from Thryssa setirostris ( Engraulidae ), Joryma brachysoma ( Pillai, 1964) from Sardinella brachysoma ( Clupeidae ), Joryma tartoor ( Pillai, 1954) from Opisthopterus tardoore ( Pristigasteridae ), and Joryma malabaricus Aneesh, Helna & Trilles, 2018 from Escualosa thoracata ( Clupeidae ). The remaining two species of Joryma show oligoxenous host specificity; J. sawayah is known from two hosts, Ilisha melastoma ( Pristigasteridae ) and Terapon puta ( Terapontidae ), and Joryma hilsae Rameshkumar, Ravichandran & Trilles, 2011 recorded from four host fishes including two clupeid fishes Sardinella sp. and Hilsa kelee , one engraulid fish Stolephorus commersonnii and a pristigasterid fish Pellona ditchela .

All five species of Joryma are described from India, with the exception of J. sawayah from Kuwait. Joryma spp. Show unique site-specific parasitization; large ovig. females are attached to the inner wall of the operculum, close to the postero-dorsal corner of the gill chamber with the body upside down; juvenile males are attached to the opposite gill chamber more or less in the same position ( Aneesh et al. 2018b).