Syrrhoe oluta J. L. Barnard 1972

Syrrhoe oluta

DIAGNOSIS.—Forehead protuberant, lateral cephalic lobe not sharp; eyes absent; article 1 of antenna 1 not elongate and lacking tooth, article 2 elongate and with mediodistal tooth; coxa 1 extremely broadened apically and acutely produced forward, coxa 2 scarcely tapering, posterior lobe of coxa 3 half or more total coxal height; gnathopodal palms with one serrate spine; article 2 of pereopod 5 expanded and ventrally truncate, posterior teeth small to medium; pereonite 7 and pleonites 1–5 each with one small to medium dorsoposterior tooth; epimera 1–2 with small posteroventral tooth, epimeron 3 with small double tooth; uropod 3 not exceeding uropods 1–2, peduncle short; telson elongate, cleft more than 85 percent its length.

DESCRIPTION.—Cephalon with strong forehead, anterior and dorsal margins forming acute angle, rostrum sharp and pointing ventrally, rostral base forming proximal keel separated from secondary midsagittal keel projecting anteriorly by falciform notch; articles 1 and 2 of antenna 1 subequal in length, article 3 about half as long, article 1 with rudimentary (type) or strong (Oregon) distomedial cusp, article 2 with strong reverted cusp; article 4 of antenna 2 much shorter than article 5, gland cone weak; coxa 1 strongly produced forward by means of anterior conical process but unlike other syrrhoes, coxa 1 broadly expanded, thus coxa 2 not bent forward and coxa 3 not extended forward by anteroventral prolongation to fit unusual posterior margin of coxa 1 in sequence; coxa 2 tapering slightly distally and 2-serrate distally; coxa 4 comma-shaped; gnathopod 1 of medium stoutness for genus, gnathopod 2 extremely slender and elongate; article 6 of pereopods 1–2 stout and bearing very dense brush of distal setae; posterior margins of second articles on pereopods 3–5 coarsely and sparsely serrate, posteroventral corners more (Oregon) or less (Colombia) protruding; distolateral peduncular margins of uropods 1–2 with long and short cusp respectively, outer rami distally simple; telson elongate and cleft almost to base; body essentially without serrations, only dorsoposterior angles of pereonites 7 and pleonites 1–5 with one tooth each, that on pleonite 3 larger than on others; no nodules present; pleonal epimera 1–2 with small posteroventral point, epimeron 3 with sinuous posterior margin and apparently bifid at posteroventral corner.

HOLOTYPE.—AMNH 14,402 male, 7.0 mm, pereopod 5 missing.

TYPE-LOCALITY.—Vema 15–38, off Pacific Colombia, 05°00′N, 79°04′W, 3023–3251 m, 15 November 1958.

MATERIAL.—The holotype and Oregon 81 (1); Oregon 82 (1).

RELATIONSHIP.—This species has closest affinities with S. papyracea Stebbing (1888) in view of its head, but the following strong differences occur in the new species: (1) the telson is elongate and more deeply cleft; (2) coxa 1 is broadly expanded ventrally and therefore coxa 2 is not bent forward and coxa 3 follows suit; coxa 3 has a smooth posterior margin and coxa 4 is more comma-shaped; (3) no accessory serrations occur on the pleonites; (4) the outer ramus of uropod 1 lacks a distal spine; (5) article 4 of antenna 2 is relatively much shorter and the gland cone is much weaker; (6) pereopods 1–2 are more strongly developed, article 6 is stouter and the distal setal brush is more highly elaborated; (7) the posterior margin of article 2 on pereopod 3 (and usually 4–5) protrudes more strongly.

Most of the differences noted above also apply to S. longifrons Shoemaker (1964) except that the latter has a deeply cleft telson like S. oluta.

Oregon to Colombia, 2798–3251 m.