Cirolana mimulus, Schotte & Kensley, 2005

Schotte, Marilyn & Kensley, Brian, 2005, New species and records of Flabellifera from the Indian Ocean (Crustacea: Peracarida: Isopoda), Journal of Natural History 39 (16), pp. 1211-1282 : 1223-1226

Cirolana mimulus sp. nov.

( Figures 7 , 8 )

Material examined

Holotype: USNM 280275 , one male (5.3 mm), in clumps of coralline alga Amphiroa sp. on reef flat, Anse Marie Louise , Mahe´, Seychelles, 1 m, 21 February 1989 . Paratypes: USNM 280276 , 86 specimens, same data as holotype .

Other material examined. USNM 280277 , 150 specimens from eight stations, algal turf, rubble, coralline algae, on reef flat, Mahé Island, Seychelles, 0.5–1.5 m .

Description

Male. Body about three times as long as greatest width. Cephalon with submarginal anterior and faint interocular sutures. Integument smooth. Pereonite 1 with single lateral suture; coxae all with entire carina, posterolateral angles of coxae 5–7 acute. Pleonite 1 visible in lateral view, not completely overlapped by coxa of pereonite 7. Pleotelson broadly rounded, armed with eight apical spine-like setae amongst plumose marginal setae.

Antennular peduncle articles 1 and 2 fused; article 3, slightly shorter than articles 1 and 2 combined; flagellum of 10–11 articles. Antennal flagellum of 24 articles, extending to pereonite 4. Frontal lamina overlapped by rostrum, pentagonal, width two-thirds of length. Mandible as figured, with three long setae at junction of molar process. Maxilla 1 lateral lobe with nine stout and seven shorter, simple setules. Maxilla 2 as figured. Maxillipedal endite with two coupling hooks and four circumplumose setae.

Pereopod 1, propodus bearing large conspicuous seta at posterodistal angle; merus with five very stout, short, blunt spine-like setae on posterior margin. Pereopod 2 as figured. Pereopod 7, carpus with one and merus with two, long, stout complex setae at posterodistal angle (see enlarged view) among cluster of other fringed and simple setae. Penes lacking, vasa differentia openings inconspicuous.

Pleopod 1 with four coupling hooks and two plumose setae; endopod 73% width of exopod. Pleopod 2 with three coupling hooks and four plumose setae; appendix masculina straight, length about 28 times basal width, apex acute bearing several fine setae, extending about one-third beyond endopod. Pleopods 3 and 4 similar, peduncle of pleopod 3 with one more plumose seta; exopod sutures complete. Pleopod 5 peduncle without coupling hooks, endopod without setae. Uropodal exopod length more than three times greatest width, subequal in length to endopod; lateral margin with seven spine-like setae, apex subbifid, medial margin bearing three short spine-like setules amongst plumose setae; a few short setae scattered on surface near lateral margin. Uropodal endopod subequal in length to pleotelson; lateral margin with two (very occasionally three) short spine-like setae; apex bifid with several long plumose setae emerging; medial margin with five spine-like setae amongst long plumose setae.

Female. Similar to male except for sexual characters.

Remarks

Cirolana mimulus can be distinguished from C. aldabrensis sp. nov. described herein, by the spination of the uropods and pleotelson, e.g. in having eight apical setules on the pleotelson (versus six) and by the lack of penes. The new species is much more similar to C. mascarenensis Müller, 1991 but differs in subtle ways: antennal articles 1 and 2 are fused in the Seychelles species, which also has anterior and interocular furrows on the cephalon (not shown in Müller’s drawings), a relatively shorter appendix masculina and a complex of robust setae on pereopod 7. The easiest character to use in separation is the number of stout setules on the lateral margin of the uropodal endopod: five in Müller’s species versus two in C. mimulus .

Etymology

The specific name is from the Latin diminutive of ‘‘mimus’’ (imitator), referring to its great similarity to another Indian Ocean species, C. mascarenensis Müller, 1991 from Réunion Island.

Figures

Figure 7. Cirolana mimulus sp. nov. (A) Male, dorsal view; (B) male, lateral view; (C) frons; (D) left mandible; (E) maxilliped; (F) anterior pleon in ventral view; (G) uropod; (H) right mandible; (I) apical margin of pleotelson; (J) maxilla 2; (K) maxilla 1.

Figure 8. Cirolana mimulus sp. nov. (A) Pereopod 1; (B) pereopod 2; (C) dactyl of pereopod 1; (D) seta from merus of pereopod 2; (E) pereopod 7; (F) pleopod 1; (G) male pleopod 2; (H) pleopod 3; (I) pleopod 4; (J) apex of copulatory stylet; (K) pleopod 5.