Paradynamene Richardson, 1905 : 305

Khalaji-Pirbalouty, Valiallah, 2018, Redescription of Cerceis biforamina Javed & Yousuf, 1996 from the Gulf of Oman (Crustacea: Isopoda: Sphaeromatidae) with remarks on the status of Cymodoce insolita Yousuf, 2011, Zootaxa 4472 (2), pp. 375-384 : 376-378

Paradynamene Richardson, 1905: 305 .

Circeis Baker, 1908: 153 [lapsus].

Cerceis tridentate intermedia Baker (1926) .

Cerceis Milne Edwards, 1840: 221 .—Haswell, 1882: 191.— Baker, 1926: 270.— Hale, 1929: 301.— Nierstrasz, 1931: 215.— Barnard, 1936: 183.— Pillai, 1954: 83.— Glynn, 1970: 28.— Harrison and Holdich, 1982: 433; 1984: 377.— Kussakin and Malyutina, 1993: 1182.

Type species: Cerceis tridentata H. Milne Edwards, 1840 . (Type designation: Harrison and Holdich, 1982).

Diagnosis. Body markedly flattened, not strongly domed, lateral margins subparallel, tapering slightly toward anterior end. Anterior margin of head narrowly rounded, extended anteriorly to cover proximal regions of antennae, posterior margin extending well beyond eyes. Rostral process, epistome, antenna and basal antennular articles usually not visible in dorsal view. Pleon with long suture lines extending to lateral margins. Pleotelson vaulted, tapering evenly toward deep distal notch. Article 1 of antennular peduncle broad, bearing acute distal processes, mesial distal process longer and embracing article 2; lateral process does not reach middle of mesial margin of peduncle article 2; peduncle article 3 narrow and shortest one. Pleopods 1 and 2 with exopod and endopod distolateral margins bearing pointed serrations (teeth); exopod of pleopod 1, has longitudinal axis strongly oblique. Appendix masculina arising sub-medially, extending well beyond endopod distal margin, rather broad at base and tapering to narrowly rounded apex. Pleopod 4 exopod lateral margin with tiny triangular lobe proximally.

Description. Head and pereonites 1 – 6 lacking dorsal processes. Rostral process and epistome never visible in dorsal view. Eyes large, located at dorsolateral margin of head. Pereonite 1 lateral margins anteriorly produced, laterally enclosing head. Pereonites 1 – 7 posterior margin with fringe of small setae; pereonites 2 – 7 coxal plates with clearly visible sutures. Pleon with two long, separate and parallel sutures at each side, dorsal surface covered with small setae or tubercles. Pleotelson with deep apical notch.

Antennula short, not reaching to posterior margin of pereonite 1, peduncle article 1 longer than articles 2 and 3 together, bearing two acute distal processes, inferior semilunar process being much longer than superior one; article 2 short bearing, curved, inferior distal tooth; flagellum shorter than peduncle. Antenna slender, peduncle articles 1– 3 short, article 5 longest; flagellum longer than peduncle.

Left mandible incisor and lacinia mobilis multicuspid; molar process prominent, spine row of serrate curved spines present. Maxillula mesial lobe with 4 pectinate RS, lateral lobe with about 10 RS some or all serrate. Maxilla lateral and middle endites each with 9 – 11 curved pectinate RS. Maxilliped endite lateral margin strongly convex, mesial margin with 1 coupling hook; palp articles 2 – 4 with weakly pronounced and setosed lobes.

Pereopods all ambulatory; superior margins of ischium to propodus not bearing fine setae fringe; with simple secondary unguis. Pereopod 1 shorter and robust than pereopods 2–7; pereopod 2 similar in proportion to pereopod 3.

Penial processes short, entirely separate, tapering smoothly from base, with bluntly rounded apex.

Pleopod 1 exopod with longitudinal axis strongly oblique, distolateral margin bearing acute serrations (teeth); endopod triangular in shape, distolateral margin weakly serrated. Pleopod 2 exopod longer than endopod, distolateral margin with acute serrations (teeth); appendix masculina inserted sub-medially, extending well beyond endopod distal margin. Pleopod 3 exopod with transverse suture; endopod of similar proportions to exopod. Pleopod 4 rami without PMS, thickened transverse ridges present, exopod lateral margin with tiny proximal triangular lobe. Pleopod 5 rami with thickened transverse ridges, exopod lateral margin with simple marginal setae, bearing 3 discrete scale patches.

Uropodal rami extending beyond pleotelsonic apex; endopod, lateral margin fringed with small dense setae, distal margin with notch; exopod slightly wider than endopod, distally with conical acute tip; medial margin lamellar, lateral margin stout, setosed and tuberculate.

Female. Smaller than male, dorsal surface smooth, body ornamentation reduced or absent. Pleotelson weakly domed; posterior margin with weak apical notch. Mouthparts metamorphosed. Marsupium formed from 4 pairs of oostegites arising from bases of pereopods 1 – 4.

Remarks. This distinctive genus is characterised by the following characters: a generally flattened body shape; antennule peduncle articles 1 broad, with two acute distal processes, mesial process longer than lateral one and embracing article 2; pleopods 1 and 2 with pointed serrations on distolateral margin of both rami, appendix masculina arising sub-medially, pleopod 4 exopod lateral margin bearing tiny triangular lobe proximally, pleopods 4 and 5 have thickened ridges on both rami. Several characters of this genus, such as mouthparts morphology; antennule peduncle articles 1 and 2 robust, articles 3 narrow and short; pleon with long suture lines, exopod of pleopod 3 with transverse suture are shared with genera such as Cymodoce Leach, 1814 and Cilicaea Leach, 1818 . These genera are separated from Cerceis by the long penial processes (extending to distal part of pleopod rami), appendix masculina inserted sub-basally (rather than sub-medially) and lacking of pleopod 4 and 5 exopod thickened transverse ridges (rather than thickened ridges on both rami). During a biodiversity project on the coastal zone isopods of the Iranian side of the Gulf of Oman from 2013 to 2015 and a literature review of Indian Ocean species of Cerceis , the description of Cerceis insolita Yousuf, 2011 was examined. It was immediately apparent that this species, described from Manora Island, Karachi coast, Pakistan belongs to Cymodoce Leach, 1814 . The following characters indicate that it cannot belong in Cerceis : frontal lamina and antennular peduncle articles visible from the dorsal view; epistome not elongated anteriorly and ending in an acute apex; lacking the acute unequal processes of antennular peduncle article 1 which is covered by the lateral margins of the second article; long penial processes with narrow apex; exopod and endopod of the pleopods 1 and 2 without deep serrations (teeth) on distolateral margins; appendix masculina arising basally; exopod of pleopods 4 and 5 without thickened transverse ridges; lacking the triangular lobe on exopod lateral margin of pleopod 4 proximally and pleopod 5 exopod distally with 5 scale patches. Based on the description and illustration given by Yasmeen (2011), Cerceis insolita matches the sub-adult male of a Cymodoce species. Comparison of the original description and illustrations of this species with Cymodoce manorii ( Nooruddin, 1965) , and Cymodoce spinula Yousuf & Javed, 2001 (recently synonymised with C. manorii ) from the same locality, reveal that Cerceis insolita is a junior subjective synonym of Cymodoce manorii ( Nooruddin, 1965) .

According to Harrison & Holdich’s (1982) brief review and the later appraisal ( Kussakin & Malyutina 1993; Khalaji-Pirbalouty 2016) the genus Cerceis contained here 12 species.

Species included:

Cerceis acuticaudata (Haswell, 1882) . South Australia.

Cerceis aspericaudata Miers, 1884 . Queensland, Australia.

Cerceis bicarinata Barnard, 1936 . Andaman Sea, Indian Ocean.

Cerceis bidentata H. Milne Edwards, 1840 . Australia.

Cerceis biforamina Javed & Yousuf, 1996 . Northern Arabian Sea (present study).

Cerceis granulata Pillai, 1954 . Kerala, India.

Cerceis picta Nierstrasz, 1931 . Philippines.

Cerceis pravipalma Harrison & Holdich, 1982 . Queensland, Australia , Southern Chinese coast , Southern Vietnam ( Kussakin & Malyutina, 1993).

Cerceis pustulosa Harrison & Holdich, 1982 . Queensland, Australia, South China Sea ( Kussakin & Malyutina, 1993).

Cerceis sinensis Kussakin & Malyutina, 1993 . South China Sea.

Cerceis tridentata H. Milne Edwards, 1840 . Queensland, Australia.

Cerceis tuberculata Müller, 1991 . Sri Lanka.