Cirolana stenoura Bruce, 1986

Bruce, Niel L., 2017, Review of the species of the Cirolana ‘ parva - group’ (Cirolanidae: Isopoda: Crustacea) in Indonesian and Singaporean waters, Zootaxa 4317 (3), pp. 401-435 : 414-415

Cirolana stenoura Bruce, 1986

( Fig. 8 )

Cirolana stenoura BruCe, 1986: 192 , figs 133–134.— BruCe, Lew Ton & Poore, 2002: 143.— RodCharoen, BruCe & Pholpunthin, 2016: 1981 .

Cirolana Cf stenoura .— Sidabalok 2013: 52.

Type and type locality. The holotype is held at AM and the type locality is Lizard Island, Great Barrier Reef, Queensland, Australia, 14°41.4'S, 145°27.5'E (AM P32168).

Material examined. All Indonesia. 2 ♂ (5.1 [dissected and illustrated], 6.7 mm), 2 ♀ (4.6, 7.2 mm), Tanjung Boi, Kaimana , West Papua, 04°2.478'S, 134°30.168'E, 13 November 2010, hand collection on intertidal reef, rubble, coll. C.M. Sidabalok and party ( MZB Cru.Iso 004) . 1 ♀ (6.5 mm), same data as previous (MTQ W52897) . 1 ♀ (3.4 mm), Tanjung Putus, Raja Ampat , 00°30'29.5''S, 130°27'21.9''E, 15 August 2015, diving 20 m, rubble and dead coral head, coll. M. Mofu and R. Mambrasar ( MZB Cru.Iso 067).

Description (male). Body 2.5 times as long as greatest width, widest at pereonite 5, lateral margins subparallel. Eyes separated by about 82% width of head, eye colour black. Pereonite 1 and coxae 2–3 each with posteroventral angle acute, posteriorly produced; coxae 5–7 with entire oblique carina; posterior margins of pereonites 5–7 smooth. Pleon with pleonite 1 largely concealed by pereonite 7; pleonites 3–5 posterior margin smooth; posterolateral angles of pleonite 2 forming acute point, extending posteriorly to anterior of pleonite 3; pleonite 3 with posterolateral margins extending clearly beyond posterior margin of pleonite 5, narrowly rounded; posterolateral margin of pleonite 4 narrowly rounded, clearly extending beyond posterior margin of pleonite 5. Pleotelson 0.7 times as long as anterior width; lateral margins straight, margins smooth, posterior margin narrowly rounded, with small distinct median point, with 6 RS.

Antennula peduncle articles 1 and 2 entirely fused; article 2 1 times as long as article 1, articles 3 and 4 1 times as long as combined lengths of articles 1 and 2, article 3 4.8 times as long as wide; flagellum with 12 articles, extending to anterior of pereonite 1. Antenna peduncle article 4 2.4 times as long as wide, 2.4 times as long as article 3, inferior margin with 3 plumose setae, and without short simple setae; article 5 1.4 times as long as article 4, 3.3 times as long as wide, inferior margin without pappose setae, anterodistal angle with cluster of 4 short simple setae; anterodistal angle with cluster of 4 long simple setae; extending to posterior of pereonite 3.

Frontal lamina longer than greatest width, lateral margins straight, diverging slightly towards anterior, anterior margin concave, with small median point.

Pereopod 1 basis 2.3 times as long as greatest width, superior distal angle without cluster of acute setae; ischium 0.5 times as long as basis, inferior margin with 1 setae, superior distal margin with 2 RS; merus inferior margin with 4 molariform RS, merus inferior margin with 1 simple seta, set as single row, superior distal angle with 2 setae; carpus inferior margin with 1 RS, carpus inferior margin with 1 simple seta; propodus 2.2 times as long as wide, inferior margin with 2 RS, inferior margin with 1 simple seta; dactylus 0.6 as long as propodus; inferior margin with setal fringe lacking. Pereopod 7 basis 2.2 times as long as greatest width, superior margin convex, inferior margin with 3 palmate setae; ischium 1.5 as long as basis, inferior margin with 3 RS, superior distal angle with 1 RS, inferior distal angle with 3 RS; merus 0.7 as long as ischium, 1.7 times as long as wide, inferior margin with 1 RS, superior distal angle with 3 RS, inferior distal angle with 5 RS; carpus 0.7 as long as ischium, 2.4 times as long as wide, inferior margin with 2 RS, superior distal angle with 4 RS, inferior distal angle with 5 RS; propodus 0.8 as long as ischium, 4.1 times as long as wide, inferior margin with 1 cluster of RS, superior distal angle with 1 slender seta, inferior distal angle with 2 RS; dactylus 0.3 as long as propodus.

Penes opening flush with surface of sternite 7, penial openings separated by 10% of sternal width.

Pleopod 1 exopod 1.5 times as long as wide, lateral margin straight, distally broadly rounded, mesial margin strongly convex, with PMS from distal one-third; endopod 2 times as long as wide, distally narrowly rounded, lateral margin straight, with PMS from distal one-third, mesial margin with PMS on distal margin only; peduncle 1.7 times as wide as long; mesial margin with 5 coupling setae. Pleopod 2 appendix masculina with parallel margins, 0.8 times as long as endopod, with appendiculate projection. Pleopods 2–5 peduncle distolateral margin with prominent acute RS, 3–5 endopods with distomesial serrate scales.

Uropod peduncle ventrolateral margin with 2 RS, lateral margin with mesial short acute RS, posterior lobe about as long as endopod; rami extending beyond pleotelson, marginal setae in single tier, apices acute. Endopod apically shallowly and evenly bifid; lateral margin weakly convex, proximal lateral margin with 1 RS; distal lateral margin with 1 RS, mesial margin weakly convex, with 5 RS. Exopod not extending to end of endopod, 3 times as long as greatest width, apically shallowly and evenly bifid; lateral margin straight, with 6 RS; mesial margin straight, with 3 RS.

Female. Similar to male.

Variation. The current material has fewer RS on exopod lateral margin than that in the original description (6– 7 vs 8–10). Of the few specimens, five were measured for uropod RS (MZB Cru.Iso 0 0 4 and MTQ W52897). Uropod exopod RS mesial margin with 2–3 (3 = 80%), lateral with 6–7 (6 = 60%); uropod endopod mesial margin with 4–6 (6 = 60%), lateral margin with 3 (100%). Number of RS on pleotelson is always 6.

Remarks. Cirolana stenoura can be identified by the dark body colour and chromatophores and posteriorly narrow pleotelson with 6 robust setae (vs 8 of other species in the ‘ parva -group’). These two characters are not known to occur in other species of the Cirolana ‘ parva -group’ which therefore identifies C. stenoura within the group. This species has been recorded in estuarine environments and tends to be an inshore shallow-water dweller rather than open-water and oceanic reefs in coral-reef ecosystems. Males of the current material have a notably shorter appendix masculina than that of the illustrated paratype from Lizard Island, Queensland (0.8 vs 1.2 endopod length) ( Bruce 1986, fig. 134D), but otherwise did not differ from the original description.

Distribution. Northern Great Barrier Reef, Queensland, Madang PNG ( Bruce 1986), Raja Ampat and Kaimana, West Papua ( Fig 1 ).

Figures

FIGURE 1. Distribution map of Cirolana ‘ parva group’ in Indo-Australian region (C – H, Indonesia; I, PNG; J – K, Australia). LoCation symbols: A = Thailand, B = Singapore, C = Lombok, D = Bitung, E = Pulau Pombo, Maluku, F = Raja Ampat, G = Kei Islands, H = Kaimana, I = Madang, J = Lizard Island, K = HinChinbrook Island. SpeCies symbols: Cirolana andamanensis (-), Cirolana arafurae (×), Cirolana improceros (v), Cirolana leptanga (O), Cirolana siamensis (O), Cirolana stenoura (A), Cirolana thailandica (Ł), Cirolana molari (Ɨ), Cirolana peisanae (+), Cirolana duo (Ŧ).

FIGURE 8. Cirolana stenoura, ♂ (5.1 mm, MZB Cru. Iso 004): A, antenna peduncle; B, antennula; C, pleon; D, uropod; E, penial openings; F, pleotelson; G, pereopod 1; H, pereopod 2; I, pereopod 7; J, pleopod 1; K, pleopod 2.