Cymodoce fuscina, 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 : 1245-1248

Cymodoce fuscina sp. nov.

( Figures 19 , 20 )

Material examined

Holotype: USNM 280292 , one male (12.0 mm), sta 2G2, Persian Gulf between Safaniya and Manifa, Saudi Arabia, seagrass beds, coll. J. McCain, 5 March 1982 . Paratypes: USNM 280293 , 38 males, 19 ovigerous females, two females, 277 juveniles, from 28 stations in Persian Gulf between Bandar Mishar and Manifa, Saudi Arabia, sand and seagrass beds, 1–4 m, coll. J. McCain, January and May 1982 .

Description

Male. Cephalon and pereonites 1–4 smooth, very sparse setae. Pereonites 5–7 each with two sometimes faint rows of small tubercles, setae increasing toward lateral margins. Pleon, anterior fused segments with many long setae near lateral margins, two strong dentate projections on posterior margin of segment, and scattered tubercles mid-region. Pleotelson with tubercles of various sizes; two rows of two elongate tubercles on either side of midline, posterior pair bifid, each of pair flanked by smaller bifid tubercle, all apically setose; anterior pair covered with short, goldenbrown setae. Posterior region at midline with small knob bearing tuft of brown setae, additional tufts on either side of knob; domed boss lacking. Apex tridentate, setose, apical notch very deep; three apices toothed, rounded distally, coplanar and of equal length.

Antennule with 16 articles in flagellum, articles 5–15 bearing one aesthetasc each; plumose setae on ventral margins on articles 1 and 2 of peduncle. Antenna with 13 articles in flagellum. Frontal lamina broad, narrowly rounded at apex. Maxilliped palp article 2 bearing long distal seta. Pereopod 1 with five very stout, fringed setae and a few smaller setules on inner margin of propodus, four similar large setae on carpus, three to four stout setae on merus. Pereopod 2 with a fringe of small setules interspersed with a few longer setae on propodus, and merus. Pereopod 7 with row of stout, simple setae on propodus; carpus and merus each bearing a ‘‘comb’’ of long, slender fringed setae on anterior margins. Penes tapering evenly to acute tip, length about 9.5 times width; margins bearing tiny setules, most obvious in posterior half. Pleopod 1, three coupling hooks on basis, plumose marginal setae on outer margins of exopod and apical region of endopod as shown. Pleopod 2 with three hooks on basis; appendix masculina tapering evenly to narrowly rounded tip, extending one-fifth length beyond endopod. Pleopod 3 with three hooks on basis. Pleopod 4 with subterminal indentation on internal margin of endopod, exopod with simple setae on external margin. Pleopod 5 with short, simple distal setae on external margin, exopod with external setae on most of margin. Uropod with rami subequal, extending very slightly beyond pleotelson apex. Endopod subrectangular, latero-distal angle toothed, with single tubercle at midline, setose laterally and ventrally near base. Exopod setose laterally and ventrally, with short, dark brown setae dorsally near external margin; internal margin arcuate, tapering to acute tip.

Sub-adult male. Dorsum smooth. Posterior margin of fused segments of pleon with two submedian tubercles, each bearing a seta. Pleotelson with ridge on either side of midline, culminating in low tubercle. Apex tridentate. Uropodal rami tapering to acute apices and extending slightly beyond pleotelson.

Ovigerous female. Dorsum smooth. Pleotelson with two submedian tubercles on posterior margin of fused segments; posteriorly, two pairs of tubercles on either side of midline. Apex of pleotelson shallowly tridentate, extending slightly beyond both rami of uropod; apices of endopod truncate, exopod with small tooth apically.

Remarks

This species differs from other species placed in this genus by having three apical lobes of the pleotelson that are coplanar, relatively slender, equal in length, rounded distally but each bearing a tiny spike, and separated by deep incisions, resulting in a marked tridentate appearance. Cymodoce tribullis Harrison and Holdich, 1984 , C. longistylis Miers, 1884 and C. pelsarti Tattersall, 1922 , Australian species, also possess three apical lobes but those in the present new species are much longer and of identical length. The maxillipedal palp, tuberculate pleon and pleotelson, and shape of the uropodal rami are characteristic of the genus, of which C. truncata Leach, 1814 is the type species. These characters are consistent with Harrison and Holdich’s (1984) diagnosis of Cymodoce (s. str.). It lacks, however, the hemispherical dome just anterior to the pleotelsonic notch which is listed by Bruce (1997) as a possible apomorphy for Cymodoce s. str. The pereopods are also similar to the type species with regards to setation. The shape of the uropods and pleotelson seem somewhat similar to those of the poorly described C. aculeata Haswell, 1881 but lack of details in the description and lack of illustrations of appendages prevent further comparison. The structure of the brood pouch is consistent with that characterizing the genus (Harrison 1984).

Etymology

The specific name, from the Latin ‘‘fuscina’’, used as a noun in apposition, means ‘‘trident’’ and refers to the shape of the three-pronged pleotelsonic apex.

Figures

Figure 19. Cymodoce fuscina sp. nov. (A) Male, dorsal view; (B) antennule; (C) antenna; (D) frontal lamina; (E) pleotelson and uropods, ventral view; (F) immature pleon, dorsal view; (G) maxilliped; (H) female, pleon; (I) penes; (J) left mandible; (K) male, lateral view.

Figure 20. Cymodoce fuscina sp. nov. (A) Pereopod 1; (B) pleopod 1; (C) male pleopod 2; (D) pleopod 3; (E) pleopod 4; (F) pleopod 5; (G) pereopod 7; (H) pereopod 2.