Cirolana mclaughlinae, Bruce & Brandt, 2006

Bruce, Niel L. & Brandt, Angelika, 2006, A new species of Cirolana Leach, 1818 (Crustacea, Isopoda, Cirolanidae) from the western Ross Sea, Antarctica, the first record of the genus from polar waters, Zoosystema 28 (2), pp. 315-324 : 317-323

Cirolana mclaughlinae n. sp.

( Figs 1-4 )

TYPE MATERIAL. — Antarctica, western Ross Sea. Holotype: BIOROSS, RV Tangaroa , stn TAN0402/14, 71°43.88’S, 171°45.00’E, 451 m, 2.II.2004, ♂ 14.9 mm ( NIWA 17948 ).

Paratypes: same data as holotype, 9 ♂♂, 12.5 (dissected), 12.5, 12.5, 12.3, 12.0, 11.9, 11.5, 11.5, 10.3 mm ; 7 ♀♀, non-ovig. 12.5, 12.4 (dissected mx2), 12.0, 11.5, 9.3, 9.0, 8.5 mm; 2 mancas, 7.2, 6.5 mm ( NIWA 17949 ) .

OTHER MATERIAL EXAMINED (sex not recorded). — Antarctica, western Ross Sea. BIOROSS, RV Tangaroa , stn TAN0402/14, 71°43.88’S, 171°45.00’E,

451 m, 5.II.2004, 6 specimens ( NIWA 17950 ). — Stn TAN0402/15, 71°43.67-43.85’S, 171°44.12-44.67’E, 466-467 m, 5.II.2004, 2 specimens ( NIWA 17951 , NIWA 17962 ). — Stn TAN0402/17, 71°44.39-44.11’S, 171°39.24-39.70’E, 409- 403 m, 5.II.2004, 1 specimen ( NIWA 17952 ). — Stn TAN0402/82, 72°03.63-03.89’S, 172°54.23-54.77’E, 526-527 m, 14.II.2004, 1 specimen ( NIWA 17953 ). — Stn TAN0402/107, 71°16.63’S, 170°36.13’E, 400 m, 18.II.2004, 4 specimens ( NMNZ Cr.10021). — Stn TAN0402/108, 71°16.63-16.64’S, 170°35.98-36.91’E, 400-405 m, 18.II.2004, 1 specimen ( NIWA 17954 ) ; 1 specimen ( NIWA 17955 ) ; 9 specimens (MNHN-Is5887). — Stn TAN0402/112, 71°17.61- 17.77’S, 170°34.60-35.45’E, 346-357 m, 18.II.2004, 23 specimens ( NIWA 17956 , NIWA 17957 ). — Stn TAN0402/116, 71°17.93-18.21’S, 170°32.43- 33.02’E, 312-315 m, 18.II.2004, 10 specimens ( NIWA 17958 ). — Stn TAN0402/117, 71°18.55’S, 170°34.39’E, 322 m, 18.II.2004, 1 specimen ( NIWA 17959 ). — Stn TAN0402/150, 71°58.77-58.91’S, 171°58.09-58.41’E, 480- 461 m, 26.II.2004, 1 specimen ( NIWA 17960 ). — Stn TAN0402/156, 71°59.56’S, 172°12.42’E, 675 m, 26.II.2004, 4 specimens ( NIWA 17961 ) .

ETYMOLOGY. — Named for Pat McLaughlin, in recognition of her considerable contribution to knowledge of the Crustacea , the Paguroidea in particular.

DISTRIBUTION. — Known from several locations in the western Ross Sea, at latitude 71- 72°S, at depths from 312 to 675 m.

DESCRIPTION

Male

Body 2.3 times as long as greatest width, dorsal surfaces coarsely pitted, widest at pereonite 5, lateral margins subparallel. Head with rostral point absent; anterior margin rounded, medially weakly indented; with prominent interocular ridge. Eyes separated by about 76% width of head, each eye composed of c. five transverse rows of ommatidia, each row with c. seven ommatidia; eye colour black. Pereonite 1 and coxae 2-3 each with posteroventral angle right-angled; coxae 5-7 with entire, strongly developed oblique carina; posterior margins of pereonites 5-7 dorsally with irregular submarginal nodules. Pleon with pleonite 1 largely concealed by pereonite 7; pleonite 3-5 each with posterior margin with irregular small nodules; pleonite 2 not posteriorly produced; pleonite 3 with posterolateral margins extending to but not beyond posterior margin of pleonite 5, narrowly

A new species of Cirolana from the western Ross Sea rounded; pleonite 4 clearly extending beyond posterior margin of pleonite 5, posterolateral margin narrowly rounded; pleonite 5 with posterolateral angles overlapped by lateral margins of pleonite 4. Pleotelson 0.7 times as long as anterior width, dorsal surface with two large submedian nodules anteriorly, with single median longitudinal carina (irregularly nodular, with obscure median depression); lateral margins sinuate, smooth, posteriorly narrow; posterior margin evenly rounded, without median point, with six RS.

Antennule peduncle articles 1 and 2 distinct, articulated; article 2 about as long as article 1, article 3 0.8 times as long as combined lengths of articles 1 and 2, 2.6 times as long as wide; flagellum with five articles, extending to anterior of pereonite 1. Antenna peduncle article 4 1.4 times as long as wide, 1.5 times as long as article 3, inferior margin without plumose setae, with seven short simple setae (submarginal, including distal margin); article 5 about as long as article 4, 2 times as long as wide, inferior margin without pappose setae, anterodistal angle with cluster of seven short simple setae; flagellum with 12 articles, extending to posterior of pereonite 1.

Frontal lamina with ventral surface entirely flat, longer than greatest width, lateral margins straight, diverging slightly towards anterior, anterior margin rounded, with anterolateral “step”, without median point.

Mandible molar process anterior margin with 27-30 flat teeth; without proximal cluster of long simple setae, with abundant long scale-setae; right mandible spine row composed of eight spines, left with eight spines; palp article 2 with 15 distolateral setae, palp article 3 with 20 robust biserrate setae. Maxillule mesial lobe with four large and CP RS (three large, one small); lateral lobe with 13 RS. Maxilla lateral lobe with four long, finely plumose slender setae; middle lobe with 13 long slender setae (eight ventral placed, five dorsal; some finely plumose); mesial lobe with four distal simple setae and nine proximal simple and plumose slender setae. Maxilliped palp article 2 mesial margin with nine slender setae, lateral margin distally with three slender setae; article 3 mesial margin with c. 19 slender setae, lateral margin with 10 slender setae; article 4 mesial margin with c. 13 slender setae, lateral margin with five slender setae; article 5 distal margin with eight setae (some of which are finely serrate), lateral margin with six setae; endite with four long CP setae and two coupling hooks.

Pereopod 1 basis 2.7 times as long as greatest width, superior distal angle with cluster of five short, acute setae; ischium 0.5 times as long as basis, inferior margin with eight setae (three submarginal molariform, five short acute simple), superior distal margin with one acute RS (and five simple setae); merus inferior margin with six molariform RS, set as single row, superior distal angle with five setae (two RS, three simple); carpus inferior margin with one RS (and one simple seta); propodus 2.1 times as long as wide, inferior margin with three RS (largest opposing base of dactylus); dactylus 0.5 as long as propodus; inferior margin without setal fringe. Pereopod 2 ischium inferior margin with two stout, bluntly rounded RS, superior distal margin with two RS (and three short simple setae); merus inferior margin with seven stout RS, superior distal margin with four acute RS; carpus inferodistal angle with three RS (two large, one small). Pereopod 3 similar to pereopod 2. Pereopod 6 similar to pereopod 7 (but slightly longer). Pereopod 7 basis 2.6 times as long as greatest width, superior margin convex, inferior margin with two palmate setae; ischium 0.6 as long as basis, inferior margin with six RS (set as two and four), superior distal angle with seven RS, inferior distal angle with seven RS; merus 0.7 as long as ischium, inferior margin with five RS (set as one and four), superior distal angle with 10 RS (some biserrate), inferior distal angle with four RS; carpus 0.7 as long as ischium, 1.3 times as long as wide, inferior margin with two RS, superior distal angle with 10 RS (some biserrate), inferior distal angle with seven RS; propodus as long as ischium, 3.2 times as long as wide, inferior margin with four RS (set as two and two), superior distal angle with two slender setae (and two acute RS), inferior distal angle with three RS.

Penes flat lobes separated by 5% of sternal width; penial process 2.3 times as long as basal width, tapering to narrowly rounded apex.

Pleopod 1 exopod 1.5 times as long as wide, broadly rounded distally, mesial margin strongly convex, with PMS on distal one-third, with c. 40 PMS; endopod 1.8 times as long as wide, narrowly rounded distally, lateral margin straight, with PMS on distal one-third, mesial margin with PMS on distal one-third, with c. 20 PMS; peduncle 1.5 times as wide as long; mesial margin with seven coupling hooks. Pleopod 2 exopod with c. 51 PMS,

endopod with c. 22 PMS; appendix masculina with parallel margins, 1.4 times as long as endopod, distally bluntly rounded. Pleopod 3 exopod with

c. 53 PMS, endopod with seven PMS. Pleopod 4 similar to pleopod 3. Pleopod 5 exopod with c. 47 PMS. Pleopods 2-5 peduncle distolateral margin without prominent acute RS, 3-5 endopods without distomesial serrate scales.

Uropod peduncle ventrolateral margin with nine plumose setae, without RS, lateral margin without medial short acute RS, posterior lobe about threequarters as long as endopod; rami extending to pleotelson apex, marginal setae in single tier, apices narrowly rounded. Endopod apically sub-bifid, lateral process prominent; lateral margin straight, with two RS sub-distally and two RS distally; mesial margin weakly convex, with seven RS. Exopod not extending to end of endopod, 0.8 times as long as endopod, 2.6 times as long as greatest width, apically deeply bifid, mesial process prominent; lateral margin straight, with five RS, distal marginal setae in two tiers, dorsal tier shorter than ventral tier; mesial margin weakly convex, with three RS.

Female

Similar to males, with exception of primary sexual characters.

Size

Adults measure 9.3-14.8 mm; no ovigerous females present in material examined; mancas up to 7.2 mm.

Variation

Taken from holotype and paratypes; n = 15. Pleotelson with six RS (94%), with five once. Uropod endopod (n = 28) mesial margin with four to seven RS, with five (46%) and six (32%) and seven (14%) most frequent; lateral margin with 1-4 RS, with two (36%) and three (50%) most frequent; exopod mesial margin with two to five RS, with two (21%), three (57%) and four (14%) most frequent, with five twice (one individual); lateral margin with four to six RS, with four and five most frequent (each 46%), three and six occurring once.

The marginal robust setae on the uropodal rami are irregularly set, and the level of variation is relatively high when compared to some other cirolanids (e.g., Bruce 2004). Variation is not obviously correlated with size or sex of the individuals.

REMARKS

Cirolana mclaughlinae n. sp. may be identified by the heavily and irregularly nodular and pitted dorsal surface of the posterior pereonites, pleon and pleotelson; the dorsal surface of the pleotelson has two large, submedian nodules anteriorly and a prominent irregular longitudinal ridge; and the uropods do not extend posteriorly beyond the pleotelson apex. The most similar species is the deep-water C. australis Keable, 2001 (from off southeastern Australia), which differs in being far less nodular, lacking the median longitudinal ridge on the pleotelson, has larger eyes, a more acute frontal lamina, the uropods extend beyond the pleotelson posterior margin, shorter penial processes and usually has two to four robust setae on the pleotelson posterior margin (95% of specimens – Keable 2001) compared to six (94% of specimens) in C. mclaughlinae n. sp.

Figures

FIG. 1.— Cirolana mclaughlinae n. sp.: A-H, holotype, 14.9 mm (NIWA 17948); I-K, paratype, 12.5 mm (NIWA 17949); A, dorsal view; B, lateral view; C, frons; D, head dorsal view; E, head, pereonite 1, lateral view; F, pleon, lateral view; G, pleotelson and uropods, dorsal view; H, sternite 7 and penes; I, antennule; J, antennule flagellum; K, antenna.

FIG. 2.— Cirolana mclaughlinae n. sp., paratype,12.5 mm (NIWA 17949): A, maxilliped; B, maxilliped endite; C, left mandible;D, man- dible palp; E, maxilla; F, maxillule; G, left mandible, distal; H, right mandible, distal.

FIG. 3.— Cirolana mclaughlinae n. sp.,paratype,12.5 mm (NIWA 17949):A, pereopod 1; B, pereopod 2; C, pereopod 1, tip of dactylus; D, pereopod 1 dactylus; E, pereopod 6; F, pereopod 7.

FIG. 4.— Cirolana mclaughlinae n. sp., paratype, 12.5 mm (NIWA 17949):A-D, pleopods 1-3 and 5 respectively; E, uropod;F, uropodal endopod, apex; G, uropodal exopod, apex.