Metacirolana mioskon, Sidabalok & Bruce, 2018

Sidabalok, Conni M. & Bruce, Niel L., 2018, Two new species and a new record of Metacirolana Kussakin, 1979 (Crustacea: Isopoda: Cirolanidae) from Indonesia, Zootaxa 4370 (5), pp. 519-534 : 527-532

Metacirolana mioskon sp. nov.

( Figs 5–8 )

All Indonesia. Holotype: ♂ (2.1 mm), Mioskon, Raja Ampat, 00°29'47.9''S, 130°43'33.6''E, 10 August 2015, 10 m, rubble and dead coral head, coll. E. Mamberaku and M. Mofu ( MZB Cru.Iso 081).

Paratypes: 4 ♂ (1.9, 2.0, 2.1, 2.1[dissected] mm), 11 ♀ (1.9–2.5 mm, average = 2.3 mm), same data as holotype ( MZB Cru.Iso 082) . 1 ♂ (2.0 mm), 11 ♀ (1.7–2.4 mm, average = 2.1 mm), Tanjung Putus, Raja Ampat, 00°30'29.5''S, 130°27'21.9''E, 15 August 2015, 15 m, rubble and dead coral head, coll. M. Mofu and R. Mambrasar (MZB Cru.Iso 083). 5 ♀ (not measured), same data as above (MTQ W34876) . 12 ♀ (1.6–2.4 mm, average = 2.1 mm), Tanjung Putus, Raja Ampat, 00°30'29.5''S, 130°27'21.9''E, 15 August 2015, 20 m, rubble and dead coral head, coll. M. Mofu and R. Mambrasar (MZB Cru.Iso 084). 1 ♂ (2.2 mm), 4 ♀ (2.4, 2.5, 3.0, 3.4 mm), Kepulauan Mansuar, Raja Ampat, 00°36'05.00''S, 130°33'30.2''E, 13 August 2015, 15 m, rubble and dead coral head, coll. E. Umpain (MZB Cru.Iso 085). 4 ♀ (2.2, 2.4, 2.5, 2.5 mm), Arborek, Raja Ampat, 00°33'48.6''S, 130°31'08.2''E, 8 August 2015, 10 m, rubble and dead coral head, coll. E. Mamberaku and M. Mofu (MZB Cru.Iso 086). 2 ♀ (2.0, 2.7 mm), Batu Lima, Raja Ampat , 00°26'58.8''S, 130°41'51.8''E, 16 August 2015, 20 m, coll. rubble and dead coral head, coll. M. Mofu and E. Umpain ( MZB Cru.Iso 087) . 3 ♀ (2.3, 2.4, 2.4 mm), Yenbuba, Raja Ampat, 00°26'15.9''S, 130°48'23.5''E, 15 m, rubble and dead coral head, coll. M. Mofu and E. Umpain (MZB Cru.Iso 088). 1 ♂ (2.3 mm), off Pulau Saonek Monde, Raja Ampat, 00°27'04.9''S, 130°48'14.0''E, 20 m, coll. rubble and dead coral head, coll. M. Mofu and E. Mamberaku (MZB Cru.Iso 089).

Description. Body 2.9 times as long as greatest width, dorsal surfaces smooth, widest at pereonite 5, lateral margins subparallel. Rostral point present. Eyes separated by about 46% width of head, eye colour black. Pereonite 1 and coxae 2–3 each with posteroventral angle acute; coxae 3–7 with entire oblique carina; posterior margins of pereonites 5–7 smooth. Pleon with pleonite 1 visible in dorsal view, pleonites 3–5 posterior margin smooth; posterolateral angles of pleonite 2 forming acute point, pleonite 3 posterolateral margins not extending to posterior margin of pleonite 5, acute, pleonite 4 posterolateral margin acute, extending beyond posterior margin of pleonite 5, pleonite 5 with posterolateral angles not overlapped by lateral margins of pleonite 4. Pleotelson 1.4 as long as anterior width; without longitudinal carina, smooth, lateral margins straight, margins smooth, posterior margin truncate, with small distinct median point, with 14 teeth.

Antennula peduncle article 2 2.1 as long as wide, 1.1 as long as article 1, 2.4 as long as combined articles 3 and 4; article 3 1.2 as long as wide; flagellum with 6 articles, extending to posterior of pereonite 1. Antenna peduncle article 4 1.8 times as long as wide, 1.2 times as long as article 3, and 2 short simple setae and 1 plumose seta (distal); article 5 1.7 as long as article 4, 3.9 times as long as wide, anterodistal angle with cluster of 3 short simple setae; flagellum with 9 articles, extending to middle of pereonite 3.

Frontal lamina anteriorly rounded, margin weakly projecting, 2.2 times longer than greatest width, lateral margin concave narrowing strongly to posterior.

Mandible molar process anterior margin with 15 flat teeth; without proximal cluster of long simple setae; right mandible spine row composed of 8 spines; palp article 2 with 6 setae, palp article 3 with 5 robust biserrate. Maxillula mesial lobe with 3 large CPS; lateral lobe with 9 RS. Maxilla lateral lobe with 3 long simple setae and 1 plumose; middle lobe with 2 long simple setae; mesial lobe with 3 distal simple setae. Maxilliped palp article 2 mesial margin with 2 slender setae, lateral margin distally with 1 slender seta; article 3 mesial margin with 3 slender setae, lateral margin with 1 slender seta; article 4 mesial margin with 3 slender setae, lateral margin with 1 slender seta; article 5 distal margin 4 setae, lateral margin with 1 seta; endite with 2 long CPS and 1 coupling seta.

Pereopod 1 basis 2.8 times as long as greatest width, superior distal angle without cluster of acute setae, inferior distal angle with 1 acute seta; ischium 0.6 times as long as basis, inferior margin with 1 acute seta, inferior distal margin without setae, superior distal margin with 2 long simple setae; merus inferior margin with 2 RS, inferior distal margin with 1 RS and 1 long simple seta, superior distal angle with 2 long simple setae; carpus inferior distal margin with 1 RS and 1 long simple seta; propodus 1.8 times as long as wide, inferior margin with 1 RS, inferior distal margin with 1 large RS and 2 simple setae, superior distal with 1 simple seta; dactylus as long as propodus. Pereopod 2 ischium inferior margin with 2 long simple setae, inferior distal margin with 1 RS, superior distal margin with 1 long acute seta; merus inferior margin with 2 acute RS, inferior distal margin with 1 RS and 1 long simple seta, superior distal margin with 3 long acute RS; carpus inferior distal margin with 2 long acute RS; propodus 2.1 as long as wide, with 1 cluster of acute RS, inferior margin with 1 RS, inferior distal margin with 1 large RS and 2 simple setae; dactylus 0.9 as long as propodus. Pereopod 3 similar to pereopod 2. Pereopod 6 similar to pereopod 7. Pereopod 7 basis 5.4 times as long as greatest width, superior margin convex without setae; ischium 0.6 as long as basis, inferior margin with 1 RS, inferior distal angle with 1 RS, superior distal angle with 1 RS; merus 0.3 as long as ischium, 1.6 times as long as wide, inferior margin without RS, superior distal angle with 2 RS (1 biserrate), inferior distal angle with 2 biserrate RS; carpus 0.7 as long as ischium, 2.3 times as long as wide, inferior margin with 1 RS, superior distal angle with 7 RS (6 biserrate) and 1 palmate seta, inferior distal angle with 4 biserrate RS; propodus 0.4 as long as ischium, 4.7 times as long as wide, inferior margin with 1 cluster of RS, superior distal angle with 2 slender setae, 1 plumose seta and 1 RS, inferior distal angle with 3 RS; dactylus 0.4 as long as propodus.

Penes distinct flat lobes, separated by 20.5% of sternal width.

Pleopod 1 exopod 1.8 times as long as wide, lateral margin weakly convex, distally narrowly rounded with weakly oblique medial margin, mesial margin strongly convex, with PMS from distal one-third, with ~16 PMS; endopod 1.7 times as long as wide, distally narrowly rounded, lateral margin straight, with PMS on distal margin only, mesial margin with PMS on distal margin only, endopod with ~10 PMS; peduncle 0.5 times as wide as long, mesial margin with 4 coupling setae. Pleopod 2 exopod with ~16 PMS, endopod with ~9 PMS; appendix masculina sub-basal, with parallel margins, as long as endopod, distally narrowly rounded. Pleopod 3 exopod with ~16 PMS, endopod with ~8 PMS. Pleopod 4 exopod with ~18 PMS, endopod with ~9 PMS. Pleopod 5 exopod with ~17 PMS. Pleopods 2–5 peduncle distolateral margin with prominent acute RS.

Uropod peduncle ventrolateral margin with 2 RS, lateral margin with medial short acute RS, posterior lobe 0.9 as long as endopod; rami extending to pleotelson apex, marginal setae in single tier, apices bifid. Endopod apically deeply bifid, mesial process prominent; lateral margin distally convex, without prominent excision, distal lateral margin with 4 teeth; mesial margin weakly convex, with 11 teeth. Exopod not extending to end of endopod, 2.1 times as long as greatest width, apically deeply bifid, mesial process prominent; lateral margin convex, with 4 teeth; mesial margin convex, with 4 teeth.

Female. Similar to male. No ovigerous female present.

Variation. Number of teeth on the pleotelson varies between 12 and 18 (12 = 26.8%, 13 = 19.5%; 14 = 29.3 %, 15 = 12.2%, 16 = 7.3%, 18 = 4. 9%, n = 41). Number of teeth on uropod rami (n = 16): exopod lateral 3–5 (3 = 12.5%, 4 = 81.3%, 5 = 6.2%), exopod mesial 3–4 (3 = 81.3%, 4 = 18.7%), endopod lateral 4–5 (4 = 62.5%, 5 = 37.5%), endopod mesial 8–11 (8 = 56.3%, 9 = 12.5%, 10 = 25%, 11 = 6.2%).

Remarks. Metacirolana mioskon sp. nov. is similar to M. serrata and Metacirolana lombok sp. nov. in having weakly produced rostrum, anteriorly dilated frontal lamina, similarly shaped robust setae on inferior distal of the pereopod 1 propodus, uropodal rami mesial and lateral margins are convex with sub-bifid apex mesial prominent. Metacirolana mioskon differs from the both species in having distally narrowly rounded appendix masculina, penial process that are widely separated by 20.5% of sternal width, proportionally much wider uropod exopod (0.5 vs 0.3–0.4 WL) and a more angled uropodal endopod (120° vs 90° of M. serrata ). For more comparison see the remarks for M. lombok .

Distribution. Only known in Waigeo Region, Raja Ampat, Indonesia.

Etymology. Named after the type locality.

Figures

FIGURE 5. Metacirolana mioskon sp. nov., hоlоtуpе ♂ (2.1 mm, MZB Cru.Isо 081) (А–B, E–F), paratуpе ♂ (2.1 mm, MZB Cru.Isо 082) (C–D, G–H). А, dоrsal viеw; B, latеral viеw; C, antеnnula; D, antеnna pеdunclе; E, frоns; F, pеnial prоcеss; G, plеоtеlsоn; H, urоpоd.

FIGURE 6. Metacirolana mioskon sp. nov., paratype ♂ (2.1 mm, MZB Cru.Iso 082). A, maxilliped; B, maxillula; C, right mandiblе; D, maxilla.

FIGURE 7. Metacirolana mioskon sp. nov., paratype ♂ (2.1 mm, MZB Cru.Iso 082). A, pereopod 1; B, pereopod 2; C, pеrеоpоd 6; D, pеrеоpоd 7; E, distal prоpоdus rоbust sеta.

FIGURE 8. Metacirolana mioskon sp. nov., paratype ♂ (2.1 mm, MZB Cru.Iso 082). A, pleopod 1; B, pleopod 2; C, pleopod 3; D, plеоpоd 4; E, plеоpоd 5.