Colopisthus tresesquinas, MOORE & BRUSCA, 2003

MOORE, WENDY & BRUSCA, RICHARD C., 2003, A monograph on the isopod genus Colopisthus (Crustacea: Isopoda: Cirolanidae) with the description of a new genus, Journal of Natural History 37 (11), pp. 1329-1399 : 1371-1378

Colopisthus tresesquinas new species

(figures 28–34)

Synonymy. Colopisthus parvus Müller, 1993: 212–218 , figures 72–96 (misidentification; not C. parvus: Richardson, 1902 ).

Type material examined. H  , female ( ZMB Cat. No. 26973) ; one male, three female and two juvenile paratypes; Colombia, Santa Marta , intertidal from Sargassum ; collected by H. G. Müller.

Diagnosis. Pleon with three free pleonites. Antenna 1 flagellum three-articulate. Antennae 2 flagellum seven-articulate. Maxilliped endite with four circumplumose setae and two coupling setae; palp articles 2 and 3 partly fused. P-1 to P-3 merus with two or three molariform setae on inferior margin. Carpus of P-5 with one biplumose seta on anterior-distal margin; P-6 with three biplumose setae on anteriordistal margin; P-7 with seven biplumose setae on anterior-distal margin. Pl-3 exopod with complete transverse suture.

Description of female

Dorsal surface of pereon and pleon with fine setae.

Antennae. Antenna 1 peduncular articles 1–3 with slender and palmate setae, article 4 with palmate setae; flagellum three-articulate, first article much longer than distal two articles; all flagellar articles with slender setae and jointed aesthetascs. Antennae 2 peduncular articles 2 and 3 with slender setae on anterior margin, articles 4 and 5 with biplumose and slender setae as figured; flagellum seven-articulate, all with cluster of slender setae in anterior-distal region and one or two slender setae in posterior-distal region.

Maxilliped. Endite with four circumplumose setae and two coupling setae. Palp article 1 with a jointed slender seta on medial margin; articles 2 and 3 partly fused, lateral margins with fine setae, lateral and medial margins with jointed slender setae; article 4 with one jointed seta on disto-lateral angle, one uniserrate and approximately five jointed slender setae on disto-medial angle; terminal article length greater than width, with approximately six slender (some jointed) and two uniserrate apical setae.

Maxillae. Maxilla 1 lateral lobe with one stout, seven forked and three uniserrate setae; medial lobe with one small biplumose, one slender and three stout biplumose setae. Maxilla 2 outer and medial lobes with three uniserrate apical setae; outer lobe with fine setae on lateral margin; gnathal lobe with one slender seta at base (below outer lobe), apical margin with one large circumplumose, one stout, one slender and three stout biplumose setae.

Mandible. Spine row with 14 large spines; molar process with approximately 21 small acute marginal spines; proximal palp article with one slender seta on lateral margin; middle article with two slender, six biserrate and three unequally biserrate setae; distal article with eight biserrate setae.

Pereopods 1–3. Ischium with two stout setae on inferior margin and one stout seta on superior-distal angle and anterior-distal margin; P-2 and P-3 with a molariform seta near inferior-distal angle. Merus with two or three molariform setae on inferior margin and one or two stout setae on superior-distal angle; distal margin deeply incised (notched) on anterior surface; P-1 with a connate spine on inferiordistal angle. Carpus subtriangular, inferior margin much longer than superior margin; with cluster of stout setae on inferior distal angle and two or three connate spines on inferior margin. Propodus with complex setae and connate spines on inferior margin as figured; P-1 and P-2 with two complex setae and four or five connate spines; P-3 with two complex setae and two connate spines.

Pereopods 4–7. Ischium with two or three clusters of stout setae on inferior margin; P-5 to P-7 with one or two biplumose setae at superior-distal angle. Carpus of P-5 with one biplumose seta on anterior-distal margin, P-6 with three biplumose setae on anterior-distal margin, two long biplumose setae at superior-distal angle; P-7 with seven biplumose setae on anterior-distal margin and approximately five long biplumose setae at superior-distal angle. Propodus inferior distal angle with two stout setae; posterior-distal margin with one stout seta; superior-distal angle with one stout, one or two slender and one biplumose seta.

Pleopods. Pl-1 to Pl-4 peduncle with one biplumose and three coupling setae on medial margin. Pl-2 to Pl-5 lateral margin of peduncle with one stout seta. Pl-3 to Pl-5 exopod with complete transverse suture. Pl-1 to P-4 endopod with approximately five or six PMS; exopod with approximately 13–16 PMS. Pl-5 endopod subovate, without setation; exopod with approximately seven PMS.

Uropod. Endopod with slender and palmate setae, two robust setae on medial margin and one robust seta on lateral margin; apex broadly rounded. Exopod with slender and two robust setae on medial margin; apex rounded, with five long slender setae; lateral margin with a continuous row of short slender setae; without lateral fold.

Description of male

As described for female. Appendix masculina missing from specimen; figured by Müller (1993). Secondary sexual characters typical of genus.

Distribution

This species is so far known only from the intertidal shores of Santa Marta, Colombia, where it was collected from the brown alga Sargassum .

Etymology This species is named after Tresesquinas rum, one of the gentle rums of Colombia.