Odysseylana sakijang, Sidabalok, Conni M. & Bruce, Niel L., 2015

Sidabalok, Conni M. & Bruce, Niel L., 2015, Revision of the cirolanid isopod genus Odysseylana Malyutina, 1995 (Crustacea) with description of two new species from Singapore, Zootaxa 4021 (2), pp. 351-367 : 355-360

Odysseylana sakijang sp. nov.

( Fig 2–5 )

Odysseylana sp. 3.— Bruce & Wong, 2015: 4.

Material examined. All material from Singapore. Holotype: ♂ (6.8 mm), between St John’s Island and Lazarus Island, 1.218718°N, 103.853968°E, 31 May 2013, baited trap, 25 m, stn SW 137, SS 4942, coll. N.L. Bruce & J.K. Lowry ( ZRC 2015.0359).

Paratypes: 7 ♂, 11 ♀ (6.7 mm broken [part dissected], 5.0– 6.8 mm, average 6 mm), same data as holotype ( ZRC 2015.0360, ZRC 2015.0361); 4 ♂, 16 ♀ (unmeasured) same data as holotype (MTQ W34314, MTQ W34315); 48 ♀ (42 measured, average 7.4 mm), same data as holotype ( ZRC 2015.0362). 7 ♂, 12 ♀, and 5 mancas (unmeasured), between St John’s Island and Lazarus Island, 31 May 2013, baited trap, 13.5 m, SW 138, SS 4941, coll. N.L. Bruce & J.K. Lowry (MTQ W34316).

Description. Body 2.9 times as long as greatest width, dorsal surfaces smooth, widest at pereonite 4, lateral margins subparallel. Eyes separated by about 82% width of head, each eye made up of ~5–6 transverse rows of ommatidia, each row with ~6 ocelli, eye colour black. Pereonite 1 and coxae 2–3 each with posteroventral angle rounded; coxae 5–7 with incomplete oblique carina; posterior margins of pereonites 5–7 smooth. Pleon with pleonite 1 largely concealed by pereonite 7; pleonites 4–5 posterior margin with 7 irregular small nodules on each; posterolateral angles of pleonite 2 forming acute point, not posteriorly produced; pleonite 3 with posterolateral margins not extending to posterior margin of pleonites 5, acute; clearly extending beyond posterior margin of pleonite 5, posterolateral margin of pleonite 4 rounded and extending to posterior margin of pleonite 5; pleonite 5 with posterolateral angles overlapped by lateral margins of pleonite 4. Pleotelson 0.9 times as long as anterior width, dorsal surface without longitudinal carina but with nodules on the proximal region; lateral margins straight, smooth, posterior margin sub-truncate, without median point, with 6 or 8 RS.

Antennula peduncle articles 1 and 2 distinct, articulated; article 2 0.8 times as long as article 1, articles 3 and 4 0.7 times as long as combined lengths of articles 1 and 2, article 3 1.4 times as long as wide; flagellum with 9 articles, extending to pereonite 2. Antenna peduncle article 4 2 times as long as wide, 1.6 times as long as article 3, inferior margin with 0 plumose setae, and 2 short simple setae; article 5 0.9 times as long as article 4, 2.4 times as long as wide, inferior margin with 7 pappose setae, anterodistal angle with cluster of 4 short simple setae; flagellum with 15 articles, extending to middle of pereonite 2.

Frontal lamina pentagonal, ventral surface entirely flat, 1.8 longer than greatest width, lateral margins straight and parallel, anterior margin acute, without small median point.

Mandible molar process anterior margin with 18 flat teeth; with proximal cluster of long simple setae; right mandible spine row composed of 9 spines, left with 10 spines; palp article 2 with 14 distolateral setae, palp article 3 with 4 robust biserrate setae. Maxillula lateral lobe with 13 RS. Maxilla lateral lobe with 6 long simple setae; middle lobe with 9 long simple setae; mesial lobe with 10 distal simple setae, with 10 proximal simple and plumose setae. Maxilliped palp article 2 mesial margin with 6 slender setae, lateral margin distally with 1 slender setae; article 3 mesial margin with 14 slender setae, lateral margin with 11 slender setae; article 4 mesial margin with 10 slender setae, lateral margin with 7 slender setae; article 5 distal margin 16 setae, lateral margin with 7 setae; endite with 3 long CPS, and 2 coupling setae.

Pereopod 1 basis 1.5 times as long as greatest width, superior distal angle without acute setae; ischium 0.7 times as long as basis, inferior margin with 2 setae, superior distal margin with 4 slender setae and 2 distal midmargin setae; merus inferior margin with 7 molariform RS, set as single row with 2 blunt, 1 acute and 1 slender seta, superior distal angle with 2 setae; carpus inferior margin with 1 slender setae; propodus 1.8 times as long as wide, inferior margin with 3 RS (2 on palm and 1 opposing the dactylus); dactylus 0.6 as long as propodus; inferior margin with setal fringe on propodus– ischium. Pereopod 2 ischium inferior margin with 2 stout, bluntly rounded RS and 1 acute setae, superior distal margin with 0 RS and 5 slender setae; merus inferior margin with 5 stout RS,1 acute and 1 slender seta, set as single row; dactylus 0.7 as long as propodus. Pereopod 3 similar to pereopod 2.

Pereopod 6 similar to pereopod 7. Pereopod 7 basis 1.9 times as long as greatest width, superior margin straight, inferior margin with 7 palmate setae; ischium 0.7 as long as basis, inferior margin with 0 RS, superior distal angle with 4 RS, inferior distal angle with 7 RS; merus 1.1 as long as ischium, 1.9 times as long as wide, inferior margin with 2 RS, superior distal angle with 9 RS, inferior distal angle with 10 RS; carpus 0.9 as long as ischium, 2.1 times as long as wide, inferior margin with 3 RS, superior distal angle with 6 RS, inferior distal angle with 7 RS; propodus 1.1 as long as ischium, 4 times as long as wide, inferior margin with 3 clusters of RS, superior distal angle with 1 slender setae, inferior distal angle with 3 RS; dactylus 0.3 as long as propodus.

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

Pleopod 1 exopod 1.7 times as long as wide, lateral margin distally concave, distally narrowly rounded, medial margin weakly oblique, mesial margin straight, with PMS from distal half, with ~16 PMS; endopod 2.4 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 ~42 PMS; peduncle 0.7 times as wide as long; mesial margin with 4 coupling setae. Pleopod 2 exopod with ~53 PMS, endopod with ~17 PMS; appendix masculina with parallel margins, 1.0 times as long as endopod, distally acute. Pleopod 3 exopod with ~58 PMS, endopod with ~13 PMS. Pleopod 4 exopod with ~59 PMS, endopod with ~9 PMS. Pleopod 5 exopod with ~63 PMS. Pleopods 2–5 peduncle distolateral margin with prominent acute RS, 3–5 endopods with distomesial serrate scales.

Uropod peduncle ventrolateral margin with 1 RS, 10 plumose setae, 1 acute seta and lateral margin with 1 medial short acute RS, posterior lobe about three-quarters as long as endopod; rami extending beyond pleotelson, marginal setae in single tier, endopod apex blunt and exopod apex bifid. Endopod apically not bifid; lateral margin sinuate, without prominent excision, proximal lateral margin with 0 RS; distal lateral margin with 2 RS, mesial margin weakly convex, with 6 RS. Exopod not extending to end of endopod, 4.2 times as long as greatest width, apically shallowly and equally bifid; lateral margin straight, with 5 RS; mesial margin straight, with 3 RS.

Female. Non-ovigerous females are similar to males except for the sexual characters.

Size. Adult males 5.0– 6.8 mm, mean 6.0 mm (n = 18); adult females 5.7–9.1 mm, mean 7.3 mm (n = 43).

Distribution. Known only from Singapore.

Remarks. Odysseylana sakijang sp. nov. can be identified and distinguished from all other species in the genus by the less elongate body (2.9 as long as wide compared to 3.5), smaller male size (5.0– 6.8 mm) than others (8.5–10.5 mm), the presence of small acute tubercles on the posterior margin of pleonites 4–5 and anterior surface of the pleotelson.

Odysseylana sakijang sp. nov. is most similar to Odysseylana temasek sp. nov. and O. setosa Yu & Li, 2001 . O. sakijang can be readily separated by the presence of fine, low tubercles on the posterior margin of pleonite 4 and 5 and anterior of pleotelson, an evenly rounded pleotelson, less elongate body, absence of long PMS in article 4 of antenna peduncle, the presence of lateral setae of uropod peduncle, and greater rami proportion in pleopod 1 (~70%). Odysseylana sirenkoi differs from Odysseylana sakijang sp. nov. in having a medially indented pleotelson posterior margin with plumose setae on the pleotelson surface and the uropod exopod extends posteriorly beyond the endopod and being distally narrowed.

Etymology. The epithet is the Malay word sakijang , meaning “barking deer”, and alludes to the original name of St John’s Island.

Figures

FIGURE 2. Odysseylana sakijang sp. nov., holotype (6.8 mm) (A – C); paratype (6.7 mm) (D – I): A, dorsal view; B, lateral view; C, frons; D, antenna; E, pleotelson and uropods; F, antennula; G, sternite 7 showing penial openings; H, uropod; I, uropod peduncle ventrolateral margin.

FIGURE 3. Odysseylana sakijang sp. nov., paratype (6.7 mm, ZRC 2015.0360): A, right mandible; B, molar process of right mandible; C, right mandible palp; D, maxilliped; E, maxillula; F, maxilla.

FIGURE 4. Odysseylana sakijang sp. nov., paratype (6.7 mm, ZRC 2015.0360): A, pereopod 1; B, robust setae on propodus inferodistal of pereopod 1; C, pereopod 2; D, pereopod 6; E, dactylus of pereopod 6; F, pereopod 7.

FIGURE 5. Odysseylana sakijang sp. nov., paratype (6.7 mm, ZRC 2015.0360): A – E, pleopods 1 – 5 respectively.