Cirolana swaraj, Anil & Bruce & Jayaraj, 2024

Anil, Pathan, Bruce, Niel L. & Jayaraj, Kadeparambil Arjunan, 2024, A new species of Cirolana Leach, 1818 (Isopoda, Cymothoidea, Cirolanidae), from Havelock Island, Andaman Sea, northern Indian Ocean, Zootaxa 5418 (1), pp. 57-71 : 59-67

Cirolana swaraj sp. nov.

( Figs 2−6 )

Material examined. Holotype: ♂ (6.5 mm), middle part of Neil Lagoon , Radhanagar beach, Havelock Island, Andaman Islands, 11.9845° N, 92.9508° E, 17 February 2019, gravel bottom and associated with Gracilaria salicornia bed, coll. Pathan Anil (Reg. no. BAKRZRL 2711).

Paratypes: 7♂ (7.6, 8.8, 7.1, 8.5, 7.4, 7.9, 8.4 mm) [dissected]), 12 ♀ (6.9, 7.5, 7.7, 8.4, 8.1, 7.8, 7.4, 8.5, 7.7, 8.3, 7.9, 8.9 mm [dissected]), same data and locality as holotype, (Reg. no. BAKRZRL 2712) .

Diagnosis: Pereonite 1 dorsal anterior mid-region with convex boss covered with fine ridges, pereonites 1–7 each with single transverse impressed line, posterior margin with 18, 18, 17 and 12 tubercles on pereonites 4−7 dorsal posterior margins respectively; pleonites 4−5 each with prominent median tubercle, 4 and 2 tubercules on each side of pleonites 4−5; frontal lamina 2.2 times as long as greatest width, lateral margins slightly widening to rounded anterior margin; pleotelson dorsal surface with sub-median double row of 5 tubercules, posterior lateral margins straight, posterior margin narrowly rounded with 6 RS and plumose marginal setae extending anteriorly to mid-length; uropodal exopod lateral margin with 8 RS and continuous row of plumose marginal setae.

Description of male: Body ( Fig. 2A ) 2.8 times as long as greatest width, dorsal surfaces punctuate, widest at pereonite 5, lateral margins slightly widening to freely projecting rounded anterior margin. Rostral point ( Fig. 3A ) absent. Eyes black; separated by about 85% width of head. Pereonites 1–7 each with a single transverse impressed suture; pereonite 1 and coxae 2–3 each with posteroventral angle rounded; coxae 2–7 with entire oblique carina; pereonite 1( Fig. 2C ) dorsal anterior mid-region with convex dome finely wrinkled; pereonites 2 and 3 without tubercules; pereonites 4–7 each with single row of small dorsal tubercules 18, 18, 17 and 12 on pereonites 4−7 dorsal posterior margins respectively, becoming more prominent on posterior pereonites. Pleon ( Fig. 2H , 3B ) with pleonite 1 largely concealed by pereonite 7; pleonites 3–5 with tubercles; posterolateral angles of pleonite 2 rounded, extending posteriorly to anterior of pleonite 4; pleonite 3 with row of 9 tubercles, posterolateral margins extending to but not beyond posterior margin of pleonite 4, narrowly rounded; pleonite 4 with prominent median tubercle and 4 sublateral tubercles on each side, posterolateral margins rounded, clearly extending beyond posterior margin of pleonite 5; pleonite 5 with prominent median tubercle and 2 sublateral tubercles on each side, posterolateral angles overlapped by lateral margins of pleonite 4. Pleotelson ( Fig. 3B ) 0.7 times as long as anterior width, dorsal anterior margin with pair of large submedian tubercles followed by two parallel rows of four smaller tubercles; lateral margins weakly concave; disto-lateral margins sinuate, posterior margin evenly rounded with 6 RS; lateral margin with 28 PMS extending anteriorly along half the lateral margin.

Antennula ( Fig. 2F ) peduncle articles 1 and 2 distinct, articulated; article 1 superior distal margin with 1small palmate seta and 1 short simple seta, inferior medial margin with 2 palmate setae and 2 short simple setae; article 2 0.5 times as long as article1, superior medial margin with 1 palmate seta and 1 short simple seta and inferior medial margin with 2 palmate setae; article 3 and 4 0.9 times as long as combined lengths of articles 1 and 2, article 3 1.8 times as long as wide, superior distal angle with 2 palmate setae and 2 short simple setae, distal margin with 2 palmate setae and inferior distal angle with 1 palmate, 2 short simple setae; flagellum with 9 articles, extending to posterior margin of eye.

Antenna ( Fig. 2G ) peduncle article 1 superior margin with 2 short simple setae; article 2 superior margin with 1 short simple seta; article 3 superior medial margin with 1 short simple seta, distal margin with 3 simple setae and inferior distal margin with 1 short simple seta; article 4 1.8 times as long as wide, 2.6 times as long as article 3, superior medial margin with 1 simple seta, distal margin with 3 simple setae and inferior medial margin with 1 short simple seta and distal margin with 2 simple setae; article 5 1 times as long as article 4, 2.5 times as long as wide, superior distal angle with 4 palmate setae, 1 long simple seta, distal margin with 1 palmate seta and inferior medial margin with 1 short simple seta, distal angle with 2 palmate and 2 simple setae; flagellum with 18 articles, extending to anterior of pereonite 3.

Frontal lamina ( Fig. 2E ) 2.2 times longer than greatest width, slightly widening to rounded anterior margin.

Maxilliped ( Fig. 4A ) palp article 2 mesial margin with 6 slender setae, lateral margin distally with 1 slender seta; article 3 mesial margin with 12 slender setae, lateral margin with 9 slender setae; article 4 mesial margin with 10 slender setae, lateral margin with 4 slender setae; article 5 distal margin 13 setae, lateral margin with 4 setae; endite with 5 long CPS, and 1 coupling seta.

Right mandible ( Fig. 4B ) molar process anterior margin with about 18 flat teeth; spine row composed of 8 spines; palp article 2 with 14 distolateral setae, palp article 3 with 17 biserrate RS.

Maxillule ( Fig. 4D ) mesial lobe with 3 large robust CPS; lateral lobe with 12 RS.

Maxilla ( Fig. 4C ) lateral lobe with 5 long setae; middle lobe with 13 long setae; mesial lobe with 12 proximal long CPS.

Pereopod 1 ( Fig. 5A ) basis 2.3 times as long as greatest width, inferior distal margin with 1simple acute seta; ischium 0.6 times as long as basis, inferior distal angle with 1 acute RS and superior distal angle with 2 RS; merus inferior margin with 6 molari form RS, 4 acute RS, 3 simple setae and 6 paramargina simple setae, superior distal angle with 2 slender setae; carpus inferior distal margin with 1 RS and 1slender seta; propodus 2.0 times as long as wide, inferior margin with 3 RS one of which has 1 accessory seta and 7 simple distal setae, superior distal angle with 2 simple setae; dactylus 0.7 times as long as propodus, dactylus 0.7 times as long as propodus, superior distal margin with 3 simple setae.

Pereopod 2 ( Fig. 5B ) basis superior margin with 3 palmate setae and 1 short simple seta, inferior margin with 4 simple setae, 2 of which on distal angle; ischium superior distal angle with 2 biserrate RS, anterior medial surface with 1 short simple seta and 1 acute RS, inferior distal margin with 2 stout, bluntly rounded RS, 1 acute RS and 1 simple seta; merus inferior margin with 6 stout RS and 1 long simple seta, superior distal margin with 3 RS, distal margin with 1 acute RS; carpus inferodistal angle with 2 RS and 1 simple long seta, distal margin with 2 simple setae; propodus 1.7 times as long as wide; dactylus 0.9 times as long as propodus, dactylus superior distal margin with 2 simple setae. Pereopod 3 similar to pereopod 2.

Pereopod 4 ( Fig. 5C ) intermediate in form between pereopod 3 and pereopod 5. Pereopod 6 ( Fig. 5D ) similar to pereopod 7. Pereopod 7 ( Fig. 5E ) basis 2.8 times as long as greatest width, superior margin convex with 4 palmate setae and 8 simple short setae, dorsal anterior surface with 1 palmate seta and 3 simple short setae and inferior distal angle with 4 simple setae; ischium 0.6 times as long as basis, superior distal angle with 6 RS two of which biserrate, 1 spinulate and 3 simple RS, inferior margin with 7 RS (set in groups of 3, 1 and 3), inferior distal angle with 2 RS; merus 0.7 times as long as ischium, 1.3 times as long as wide, inferior margin with 4 RS (set in groups of 1 and 3), inferior distal angle with 6 RS, superior distal angle with 12 RS (2 simple and 9 biserrate); carpus 0.9 times as long as ischium, 1.7 times as long as wide, inferior margin with 3 RS, inferior distal angle with 10 RS (6 simple and 4 biserrate), superior distal angle with 16 RS (simple and biserrate); propodus 1.0 time as long as ischium, 4.4 times as long as wide, inferior margin with 4 RS (set in group 2 and 2), inferior distal angle with 2 RS and 1 simple seta, superior distal angle with 2 RS, slender setae and 1 palmate seta; dactylus 0.4 times as long as propodus with 3 setae and 1 simple seta on distal inferior angle.

Penes ( Fig. 2I ) low tubercles, openings separated by 25% of sternal width.

Pleopod 1 ( Fig. 6A ) peduncle 1.6 times as wide as long, mesial margin with 4 coupling hooks and 1 PMS; exopod 1.4 times as long as wide, lateral margin straight, distally broadly rounded, mesial margin strongly convex, with 26 PMS from distal one-third; endopod 2.2 times as long as wide, distally broadly rounded, lateral margin sinuate, with 9 PMS on distal margins only. Pleopod 2 ( Fig. 6B ) peduncle mesial margin with 4 coupling hooks and 3 PMS; exopod with 34 PMS, endopod with 11 PMS; appendix masculina with parallel margins, 1.1 times as long as endopod, distally acute. Pleopod 3 ( Fig. 6C ) peduncle mesial margin with 4 coupling hooks and 3 PMS; exopod with 38 PMS, endopod with 11 PMS. Pleopod 4 ( Fig. 6D ) peduncle mesial margin with 3 coupling hooks and 3 PMS; exopod with 36 PMS, endopod with 9 PMS. Pleopod 5 ( Fig. 6E ) exopod with 34 PMS. Pleopods 1–5 peduncle distolateral margin with prominent acute RS.

Uropod ( Fig. 3C ) peduncle ventrolateral margin with 2 RS, lateral margin with 1 mesial short acute RS, posterior lobe about one-half as long as endopod bearing 2 acute RS and 2 simple setae; rami extending beyond pleotelson, marginal setae in single tier, apices broadly round. Endopod ( Fig. 3C ) apically not bifid; lateral margin distally convex, without prominent excision, with 3 RS, mesial margin strongly convex, with 8 RS. Exopod ( Fig. 3C ) not extending to end of endopod, 1.5 times as long as greatest width, apically shallowly and equally sub-bifid; lateral margin weakly convex, with 5 RS; mesial margin convex, with 3 RS.

Female. Similar to the male but without a dorsal dome on pereonite 1 and the tubercles on pleon and pleotelson and pereonites are smaller.

Variation. Pleotelson (n=20 [8♂ and 12♀]) with 6–8 RS, 6=84.1%, 8=15.9%. Uropod endopod mesial margin with 7–8 RS, with 8 (97%) most frequent, 7 (3%), lateral margin with 3 RS (100%); exopod mesial margin with 3 RS (100%); lateral margin with 5–6, with 6 (87%) most frequent and 5 (13%).

Size. Adult males (n=8) 6.5–8.8 mm (mean 7.7 mm); females (n=12) 6.9–8.9 mm (mean 7.9 mm).

Remarks: Males of Cirolana swaraj sp. nov., can be identified by the pereonite 1 dorsal anterior mid-region with convex dome with a finely wrinkled surface, a character unique to this species, and both males and females by pereonites 1–7 each with a single transverse impressed line and having 18, 18, 17 and 12 tubercles on pereonites 4−7 dorsal posterior margins respectively; pleonites 4 and 5 each with prominent median tubercle, and four and two tubercules on each side of pleonites 4 and 5 respectively; frontal lamina 2.2 times as longer than greatest width, slightly widening to the rounded anterior margin; pleotelson dorsal surface with double row of five sub-median tubercules, posterior lateral margins sinuate with a narrowly rounded apex is with six robust setae and plumose marginal setae extending well to the anterior; the uropodal exopod lateral margin has eight robust setae and a continuous row of plumose marginal setae.

Cirolana swaraj sp. nov., belongs with a small group of species, referred to as ‘Clade D’ by Sidabalok (2019). This clade comprises Cirolana browni Van Name, 1936 , Cirolana cranchi Leach, 1818 , Cirolana pustulosa Hale, 1925 , Cirolana willeyi Stebbing, 1904 , Cirolana harfordi ( Lockington 1877) . The clade will likely be found to include other species that were not included in the analysis. One of the characters of this clade is that the pleotelson marginal setae extend well anterior to the robust setae, the uropod setation is usually dimorphic, with males having more abundant setae, pleonite 4 is not posteriorly extended, penial processes are lacking, and all species are to a greater or lesser degree nodular, though in the two cold-water species, the eastern Atlantic C. cranchi and the northern Pacific C. harfordi , the nodules are quite small. Of these five species C. browni , C. cranchii and C. harfordi are well out of range and lack the larger nodules and ornamentation ( Bruce & Ellis 1983; Bruce 1986, Brusca et al. 1995) of C. swaraj sp. nov,. Cirolana willeyi , a strongly nodular species with, in adult males, prominent nodules on the head and pereonite 1, is immediately distinguished by have a distinctly pentagonal frontal lamina, the uropod exopod with an acute apex and the endopod with a narrowly rounded apex (both rami are rounded in C. swaraj sp. nov.). Cirolana pustolosa has a rounded frontal lamina, but has strongly sinuate pleotelson lateral margins, with elongate and bluntly rounded uropodal rami that extend well beyond the pleotelson posterior margin.

Cirolana swaraj sp. nov. appears most similar to some of the figures given for the very poorly known C. fluviatilis Stebbing, 1902 ( Barnard 1935; Chilton 1924, 1926; Pillai 1967; Sanil et al. 2009). It appears that most records of C. fluviatilis other than those from South Africa do not correspond with the South African species and are misidentifications. Barnard (1935, fig. 19) gave comparative figures of a syntype (‘cotype’) and of a specimen from East London, and of specimens from Travancore and Chilika Lake. C. swaraj sp. nov., is immediately distinguished by the males having a prominent dome on pereonite 1 and, in all cases, having the pleotelson longitudinal ridges consisting of a large anterior nodule and row of short acute nodules progressively decreasing in size posteriorly, while the uropodal endopod of C. swaraj sp.nov., is far more broadly rounded than that of South African C. fluviatilis . With regard to C. ‘ fluviatilis ’ from Travancore ( Barnard 1935 fig. 1a), the uropod endopod shape is more similar to that of C. swaraj sp.nov., but is more posteriorly straight, and the pattern of nodules on the pleon and pleotelson for both species is different, with the Travancore nodules being smaller, lacking a dominant median nodule, and additionally, the pleotelson lateral margins are distinctly convex, with the telson having a broadly rounded pleotelson. None of the records of C. fluviatilis from South Africa and from India have been fully described, but all records other than those from South Africa are misidentifications and as such those records must be disregarded.

Although there is a strong superficial resemblance to several species of the Cirolana ‘ pleonastica group’, all these species can be ruled out by having the uropodal exopod with only three widely spaced small robust setae, and discontinuous slender setae, and the pleotelson marginal slender setae not extending anteriorly from the posterior row of robust setae.

Distribution. Known only from the type locality, South Andaman, Andaman Islands.

Etymology. The epithet is the Indian name of Havelock Island; noun in apposition.

Figures

FIGURE 2. Cirolana swaraj sp. nov., holotype male (6.5 mm, Reg. no. BAKRZRL 2711). A, dorsal view; B, lateral view; C, head and pereonite 1; D, dorsal tubercles on pereonite 7; E, frontal lamina; F, antennula; G, antenna; H, pleon; I, penial opening, sternite.

FIGURE 3. Cirolana swaraj sp. nov., holotype male (6.5 mm, Reg. no. BAKRZRL 2711). A, head; B, pleotelson; C, uropods.

FIGURE 4. Cirolana swaraj sp. nov., holotype male (6.5 mm, Reg. no. BAKRZRL 2711). A, maxilliped; B, mandible; C, maxilla; D, maxillule.

FIGURE 5. Cirolana swaraj sp. nov., holotype male (6.5 mm, Reg. no. BAKRZRL 2711). A, pereopod 1; B, pereopod 2; C, pereopod 4; D, pereopod 6; E, pereopod 7.

FIGURE 6. Cirolana swaraj sp. nov., holotype male (6.5 mm, Reg. no. BAKRZRL 2711). A–E, pleopods 1–5 respectively.