Rhepoxynius vigitegus (J. L. Barnard 1971)

Rhepoxynius vigitegus (J.L. Barnard)

Paraphoxus vigitegus J.L. Barnard, 1971:70–74, figs. 44–46.

DESCRIPTION OF FEMALE (female “w,” 4.76 mm).—Head about 18 percent of total body length, greatest width about 80 percent of length, rostrum constricted, narrow, short, reaching middle of article 2 on antenna 1. Eyes tiny, clear of pigment, ommatidia ordinary. Article 1 of peduncle on antenna 1 about 1.3 times as long as wide, about 2.3 times as wide as article 2, ventral margin with about 6 setules, weakly produced dorsal apex with 2 setules-setae, article 2 about 0.7 times as long as article 1, with widely spread ventral row of 7 setae, primary flagellum with 8 articles, about 0.6 times as long as peduncle, bearing 1 short aesthetasc each on articles 3–7; accessory flagellum with 7 articles. Ensiform process of antenna 2 very long; article 3 with thin apicodorsal spine; spine formula of article 4 = 3–3–2, dorsal margin with notch bearing 5 setae, ventral margin with 9 groups of 1–2 long to short setae, 1 ventrodistal long spine; article 5 about 0.7 times as long as article 4, facial spine formula = 0, dorsal margin bearing 2 sets of small setae, ventral margin with 5 sets of 1 long seta each, 3 ventrodistal long to medium spines all set facially; flagellum about 1.1 times as long as articles 4–5 of peduncle combined, with 9 articles.

Sharp epistomal cusp curled upward into hook. Mandibles with weak palpar hump, right incisor with 3 teeth, third in midddle, left incisor with 3 hump teeth in 2 branches; right lacinia mobilis bifid, distal branch little shorter than proximal, both branches, narrow, pointed, left lacinia mobilis with 5 teeth, middle teeth scarcely shortened; right rakers 9 plus 2 rudimentaries, left rakers 10 plus 1 rudimentary; molars composed of short bulbous protrusions, right molar with 5 primarily medium spines, no spine disjunct, left molar with 6 primarily medium spines, no spine disjunct, molars without plume; palp article 1 short, article 2 with 1 short inner apical seta and 1 other short inner seta, article 3 about 0.9 times as long as article 2, oblique apex with 11 spine-setae, basofacial formula = 0–2. Each outer lobe of lower lip with 1 cone. Inner plate of maxilla 1 ordinary, bearing 1 medium apical pluseta, 1 similar apicomedial seta, 2 apicolateral shorter setae, palp article 2 with 1 apical spine, 1 apicolateral, 3 apicomedial, and 7 submarginal setae. Plates of maxilla 2 extending subequally, outer much broader than inner, outer with 2 apicolateral setae, inner with 2 medial setae. Inner plate of maxilliped with 1 large thick apical spine, 2 apicofacial setae, 5 medial setae, outer plate with 7 medial spines, no apicolateral setae or cusp, palp article 1 with 1 apicolateral seta, article 2 with 3 groups of 4 lateral setae, medial margin of article 2 moderately setose, article 3 with 8 facial setae, 3 lateral setae, nail 8 of article 4 short, completely fused, with 2 accessory setules.

Coxa 1 not expanded apically, anterior margin weakly convex, straight, main ventral setae of coxae 1–4 = 7–7–7–4, posteriormost seta of coxa 1–4 slightly shortened, anterior and posterior margins of coxa 4 almost parallel, posterior margin almost straight, posterodorsal corner sharp-rounded, posterodorsal margin short, concave, width-length ratio of coxa 4 = 11:17.

Gnathopods with moderately thin hands moderately setose anteriorly, width ratios on articles 5–6 of gnathopods 1–2 = 28:24 and 28:25, length ratios = 65:45 and 60:43, palmar humps very small, palms transverse, article 5 of gnathopod 1 elongate, ovate, posterior margin flat, long, article 5 of gnathopod 2 elongate, ovate, posterior margin rounded, almost lobate.

Pereopod 4 stouter than pereopod 3 especially on article 5, facial setae formula on article 4 = 5 and 8 parallel to apex, on article 5 = 7 and 5, main spine of article 5 extending to M. 95 on article 6, article 5 with no proximoposterior spines, spine formula of article 6 = 6 + 7 and 7 + 7 plus no middistal seta, some spines especially long; acclivity on inner margin of dactyls of pereopods 3–4 sharp, produced as tooth, emergent setule short, midfacial pluseta ordinary. Coxae 5–7 posteroventral seta formula = 11–11–1. Articles 4–5 of pereopods 5–6 broad, facial spine rows moderately developed, facial ridge formula of article 2 on pereopods 5–7 = 0–0–0; width ratios of articles 2, 4, 5, 6 of pereopod 5 = 63:63:58:17 (article 2 width = 73 with posterior tooth), of pereopod 6 = 90:54:37:15, of pereopod 7 = 93:24:22:8; length ratios of pereopod 5 = 109:52:52:34, of pereopod 6 = 104:77:42:53, of pereopod 7 = 100:25:30:26, article 2 of pereopod 7 almost reaching apex of article 4, with 6 deep posterior castellations, posteroventral margin beveled, medial and lateral apices of articles 5–6 coarsely combed, bearing no digital processes; article 2 of pereopod 5 with large posterodorsal cusp.

Posteroventral corner of epimeron 1 rounded, posterior margin weakly convex, anteroventral margin with 7–8 short to medium setae, posteroventral face with 3 long setae set obliquely. Posteroventral corner of epimeron 2 rounded, posterior margin weakly convex, facial setae = 13, posteriormost triad set vertically and fully posterior. Posteroventral corner of epimeron 3 rounded, with 1 seta, posterior margin weakly convex, with 1 setule notch, ventral margin with 4 setae mainly posterior.

Urosomite 1 with lateral setule at base of uropod 1 and lateral ridge, articulation line almost complete, urosomite 2 with large hook dorsally. Rami of uropods 1–2 with articulate but tightly fixed apical nails, rami of uropods 1–2 naked, inner ramus of uropod 2 shortened. Peduncle of uropod 1 with 1 basofacial seta and 1 apicolateral spine, medially with 1 apical spine, no displaced spine. Peduncle of uropod 2 with 3 dorsal spines, medially with 1 medium apical spine; apicolateral corners of peduncles on uropods 1–2 without comb. Peduncle of uropod 3 with 3 ventral spines, dorsally with 1 lateral spine, 1 medial setule, rami feminine, inner extending to M. 50 on article 1 of outer ramus, apex with 1 medium seta, medial and lateral margins naked, article 2 of outer ramus ordinary, 0.22, bearing 1 short and 1 medium setae, medial margin of article 1 naked, lateral margin with 2 acclivities, spine formula = 1–1–1, setal formula = 0. Telson especially long, length-width ratio = 8:5 or 16:9, almost fully cleft, each apex narrow, rounded, lateral acclivity shallow, narrow, bearing ordinary lateral setule, seta next medial longer than setule, or additional medial setule present, midlateral setules diverse, largest medium, set at M. 50.

MALE.—Unknown.

MATERIAL.—USNM, Oregon 1, AD 1 of A.G. Carey, Jr., off mouth of Columbia River, 44°39.8′N, 124°05.9′W, 30 m, 20 June 1962, female “w,” 4.76 mm.

RELATIONSHIP.—If one keys this species on through couplet 9 of the “Key to the Species of Rhepoxynius,” the closest relationship of Rhepoxynius vigitegus falls to R. daboius; but R. vigitegus differs from R. daboius in the absence of ramal spines on uropods 1–2 and in the two characters for which R. vigitegus is unique in the Phoxocephalidae: the curled epistomal cusp and the giant dorsal spike on urosomite 2. Actually, urosomites 1 and 2 are almost solidly fused but marked with a strong suture ridge.

Rhepoxynius vigitegus is also unusual in the genus because of the shortened inner ramus of uropod 2, the spike on article 2 of pereopod 5, and the distally placed dorsolateral setule pairs on the telson.

DISTRIBUTION.—Oregon, 30 m.