Wecomedon wecomus (J. L. Barnard 1971)

Hippomedon wecomus

DIAGNOSIS.—Lateral cephalic lobes strong, moderately stout for genus, subacute; eyes faint, composed of ommatidia within weak capsule, oval, located on side of head, lacking horny lens; dorsal carina of antenna 1 obsolete, peduncle slender, article 1 of primary flagellum only one-third as long as article 1 of peduncle, lacking distal spine or spines, accessory flagellum 4-articulate, article 1 not elongate; coxae 1–3 each with posteroventral notch, coxa 4 with 3–4 posteroventral serrations, posteroventral lobe of coxa 4 broad; article 6 of gnathopod 1 about three-fourths as long as article 5, anterior and posterior margins nearly perfectly parallel, palm oblique but strongly defined from posterior margin of article 6 by 2 spines (1 drawn in figure), dactyl fitting palm and bearing subdistal inner tooth and narrow distal hood; article 5 of gnathopod 2 with strong posterodistal tuberosity, article 6 subovate, narrow distally, palm short, slightly protuberant; posterior setae on articles 5–6 of pereopods 1–2 thin; dactyls of all pereopods with weak distal hoods; article 2 of pereopod 3 tapering distally, of pereopods 4–5 not tapering distally, posterior margins of all second articles moderately serrate; peduncles of uropods 1–2 strongly spinose, rami of uropod 1 each with 1–2 marginal spines, outer ramus of uropod 2 with 2–3 spines, inner naked; uropod 3 slender, rami tapering evenly, inner ramus reaching midway along article 2 of outer ramus, latter article exceeding 35 percent length of article 1, opposite margins of rami evenly spinose, with 3 (inner) and 5 (outer) spines each; telson deeply cleft, lobes of medium breadth, each lateral margin with 2 spines and pair of setae, apices each incised and bearing 2 medium-size spines; pleonal epimeron 1 with minute point posteroventrally, epimeron 2 with medium-size, slender tooth, epimeron 3 with plain blunt tooth of medium length, lacking dorsal sinus; urosomite 1 with weak dorsal saddle and obsolescent crest, urosomites 2–3 stair-stepping normally downward; integument covered with weak irregular polygonal structure, scarcely alveolar, bearing very rare tiny spines not oriented to alveoli (similar to H. boreopacificus Gurjanova, 1962), but spinules even more rare.

Head with coniform keel between first antennae.

MALE.—One specimen bearing penial projections, otherwise like female in antennae, uropods, eyes, and other characters.

HOLOTYPE.—USNM 127130, female, 6.8 mm.

TYPE-LOCALITY.—Station 61, 44°43.8′N, 124° 18.l′W, 100 m, 25 March 1964.

MATERIAL.—Stations 60 (1), 61 (2), 71 (1), 1001 (2).

RELATIONSHIP.—This species has strong affinities with Hippomedon minusculus Gurjanova (1938, 1951, 1962) and may only be a subspecies joined to that entity. There seems to be considerable variation in spination of telson and uropod 3 in H. minusculus as taken from Gurjanova’s two sets of figures (1938 and 1962) but H. wecomus differs, nevertheless, in the shorter article 2 of the outer ramus of uropod 3 and in the shortness of the telsonic spines. The tooth on pleonal epimeron 3 of H. minusculus is slightly larger than in H. wecomus. The dorsal configuration of the urosome of H. wecomus differs from that of H. minusculus in the distinct saddle-shaped depression of urosomite 1 and the regularity of the other segments, whereas H. minusculus lacks the depression and has a very short and low urosomite 3. Hippomedon wecomus has other characters of importance, which are not described for H. minusculus, that may have specific value: the serrations of coxa 4, the thin tooth of pleonal epimeron 2, the minute tooth of pleonal epimeron 1.

Hippomedon zetesimus Hurley (1963) resembles H. wecomus but differs in the elongate and strongly armed article 1 of the primary flagellum on antenna 1, the weak palm of gnathopod 1, the lack of a discrete bulbosity on article 5 of gnathopod 2, the absence of spines on the rami of uropod 2, and the minute honeycomb sculpturing of the integument. Hippomedon subrobustus Hurley (1963) has a strongly rounded and sloping posteroventral margin on article 2 of pereopod 5.

The differences among various species of Hippomedon are so minor that one may see resemblances of H. wecomus even to others not mentioned above. A brief mention of differences of the following species from H. wecomus is as follows: H. boreopacificus Gurjanova (1962) lacks eyes, has a sharper cephalic lobe, and more obliquely rounded posterodistal margin of article 2 on pereopod 5; H. granulosus Bulycheva (1955) has an almondshaped, untapering article 6 on gnathopod 2, no tuberosity on article 5 of gnathopod 2, and a very granular integument; H. wirketis Gurjanova (1962) lacks eyes, has a sharper cephalic lobe, stouter uropod 3, densely setose anterior margin on article 2 of gnathopod 1, and a regular alveolar integument with a spinule in the center of each polygon; Hippomedon propinquus propinquus Sars (see Gurjanova, 1962) has a scarcely distinguishable palm on gnathopod 1, a strong dorsal crest on antenna 1, and an elongate article 1 on the primary flagellum.

DISTRIBUTION.—Oregon, 52–100 m.

Lepidepecreoides K. H. Barnard

Lepidepecreoides K. H. Barnard, 1932, p. 62.

DIAGNOSIS.—Lateral cephalic lobes sharp but short, head tall but often partially hidden by coxa 1 and appearing small; peduncular articles 2–3 of antenna 1 not longer than distal articles of flagellum but article 1 elongate; upper lip projecting in front of epistome and separated from it by weak invagination or tiny notch; mandibular palp 3-articulate, attached opposite molar, incisor smooth, molar triturative; lower lip and maxilla 2 ordinary; inner plate of maxilla 1 with 3 or fewer terminal setae, spines on outer plate thick, palp 2-articulate; maxilliped stout and short like typical members of Hippomedon Boeck; coxa 1 elongate and evenly rectangular, coxa 4 elongate and narrow, coxa 5 nearly as long as 4; gnathopod 1 subchelate, article 5 longer than 6, gnathopod 2 weakly chelate; article 2 of pereopod 3 with blunt posterior spur and weaker posteroventral spur; pleonal epimeron 3 lacking tooth; pleonite 4 with large dorsal tooth; uropod 2 without special notches on rami; uropod 3 of ordinary size, outer ramus 2-articulate; telson deeply cleft; pereonites 5–6 with sausage-shaped appendage on each gill.

TYPE-SPECIES.—Lepidepecreoides xenopus K. H. Barnard (1932), South Shetlands, South Georgia, Palmer Archipelago, 130–1,080 m.

RELATIONSHIP.—K. H. Barnard mentioned Lepidepecreum Bate and Westwood, Lepidepecreella Schellenberg, and Lepidepecreopsis Stephensen (= Tryphosella Bonnier) in his discussion of relationships, but Lepidepecreoides appears to have no special affinity with those genera and instead seems to have a few resemblances to Hippomedon Boeck. Lepidepecreoides differs from Hippomedon in the elongate coxa 5, the presence of a dorsal process on pleonite 4, the absence of a tooth on epimeron 3, and the gross spurs of pereopod 3. Lepidepecreoides differs from the majority of species in Hippomedon in the narrow coxa 4 and unexpanded coxa 1. It resembles Hippomedon in its overall aspect, its generally small head with sharp ocular lobes, the elongate article 1 on the flagellum of antenna 1, the outline of the prebuccal mass, the appendages on the gills, the elongate pereopods 3–5, shape of gnathopods 1–2, all of the mouthparts including the very stout and short maxillipeds, and in the uropods and telson.

Lepidepecreoides also has many characters in common with the odd members of Uristes, such as U. perspinis J. L. Barnard (1967a) and U. lepidus J. L. Barnard (1964e). But those species, like all of those in Tryphosella ( = Lepidepecreopsis) have a short and tapering coxa 1, no teeth on pereopod 3 and pleonite 4, and have somewhat shortened fifth articles of gnathopod 1.