Ericthonius parabrasiliensis, Just, 2009

Just, Jean, 2009, Ischyroceridae *, Zootaxa 2260 (1), pp. 463-486 : 475-478

Ericthonius parabrasiliensis sp. nov.

( Figs 8 , 9 )

Type material. Holotype, male, 4.6 mm, AM P70718, Watsons Bay , Lizard Island (14°39'41"S 145°26'52"E), scrapings from mooring block on sandy bottom, 8.3 m, P.B. Berents & L. Hughes, 24 February 2005 (QLD 1636) . Paratypes: 1 male, AM P70693 (QLD 1636); 1 ovigerous female, 5.2 mm, AM P70675 (QLD 1644) .

Type locality. Watsons Bay , Lizard Island, Queensland, Australia (14°39'41"S 145°26'52"E) .

Etymology. The prefix para indicates the similarity of this new species to Ericthonius brasiliensis .

Description. Based on male holotype, 4.6 mm, AM P70718.

Head. E yes large, 2/5 dorsal length of head, situated mainly within lateral lobe of head. Antenna 1 peduncular article 1 distinctly shorter than article 3; flagellum distinctly longer than peduncular article 3, with 13 articles, each with a single aesthetasc. (Antenna 2 not known in male.)

Pereon. Gnathopod 1 distinctly smaller than gnathopod 2; coxa about half length and width of coxa 2, not ventrally setose; basis with midposterior broad expansion; merus with posterodistal forward pointing spine; carpus distinctly longer than propodus; propodus length slightly less than 1.5 x width, posterior margin evenly rounded. Gnathopod 2 carpochelate; coxa 2 separated from coxa 1 and 3 (but not widely), subquadrate, about as broad as deep, much larger than 1 and 3–4, with stridulation ridges along ventral convex margin and cluster of slender setae on anteroventral margin; carpus with distinct free posterodistal expansion with two carpal teeth, posterior margin of carpus with slender setae only; propodus length 2/3 carpus length, rectangular, posterior margin with low rectangular projection in distal third and flat rounded midposterior bump; dactylus approximately 2/3 length of propodus, with apical tuft of setae. Pereopods 3–4 coxae, ventral margin setose; basis anterodistally expanded, flask shaped; merus weakly expanded. Pereopod 5 coxa ventral margin with many long slender and plumose setae, basis posterodistal corner approximately right angled. Pereopod 7 basis length approximately 1.5 width, posterodistal corner rounded right angled.

Pleon. Urosomites 1 and 2 with dorsal pair of upright slender setae. Uropod 1 peduncle dorsolateral margin with row of 5 robust setae, outer ramus with 4 lateral and 3 medial robust setae, inner ramus with 4 medial robust setae, apically with 2–3 robust setae. Uropod 2 peduncle dorsolateral margin with 3 robust setae, medial margin with single long robust seta distally, outer ramus lateral margin with 2 robust setae, medial margin without setae; inner ramus lateral margin without setae, medial margin with 3 robust setae, both rami with 2–3 robust setae apically, one of which is twice as long as the others. Uropod 3 peduncle length approximately 2.5 x greatest width, broad proximally, narrowing distally, with 4 dorsolateral slender setae; ramus length approximately 3 x width, distally cusped. Telson midlength 1/3 greatest width, lateral lobes with 2 rows of recurving hooks, distance between lobes equals width of each lobe.

Female (sexually dimorphic characters). Based on paratype, 5.2 mm, AM P70675. Gnathopod 1 basis without posterior swelling. Gnathopod 2 coxa rounded, only slightly longer than 1 and 3, with stridulation ridges ventrally; carpus projection with row of 2–4 robust setae on posterior margin and acute apex; propodus posterior margin evenly convex, with group of 3 robust setae level with ventral apex of carpus; dactylus without apical setae.

Habitat. On overgrown mooring blocks and lines, 5 to ca. 8 m depth.

Remarks. Males of Ericthonius parabrasiliensis sp. nov. are similar to E. brasiliensis ( Dana, 1853) in possessing a posterior swelling on the basis of gnathopod 1, although a much shallower one than in the latter species. No other species of Ericthonius has such a swelling on the basis of gnathopod 1. In both sexes, the eyes in E. parabrasiliensis are much larger than in E. brasiliensis ; the shape of coxae 3–4 differs, and coxa 5 in E. brasiliensis lacks a combination of long slender and plumose marginal setae.

Distribution. Australia. Queensland: Lizard Island, Great Barrier Reef (current study).

Figures

FIGURE 8. Ericthonius parabrasiliensis sp. nov., holotype, male, 4.6 mm, AM P70718, Watsons Bay, Lizard Island, Great Barrier Reef.

FIGURE 9. Ericthonius parabrasiliensis sp. nov., holotype, male, 4.6 mm, AM P70718, except F, paratype, female, 5.2 mm, AM P70675, Watsons Bay, Lizard Island, Great Barrier Reef (setae on F G1 omitted, but as in male Fig.8 G1).