Urothoides mammarta Barnard & Drummond 1979

Urothoides mammarta

DESCRIPTION OF FEMALE.—Rostrum broad from dorsal view, anterior margin broadly rounded. Eyes absent. Article 1 of antenna 1 about as wide as long, article 2 about 0.65 times as long and 0.90 times as wide as article 1; article 3 about 0.85 times as long as article 2; primary flagellum with 4 long articles attached to short stout basal article; accessory flagellum with 3 long articles, geniculation weak. Article 3 of antenna 2 with only one faciodistal setal-spine; article 4 with 7 alternately short and long dorsal spines and pair of long facial setae, ventral margin with 2 main setae; article 5 about 0.75 times as long as article 4, dorsal margin with 3 apical spines, distal face with 2 long setae, ventral margin with 2 short setae; flagellum almost 1.5 times as long as article 5 of peduncle, composed of 3 long articles, no cusps.

Prebuccal complex massive, dorsally protruding; epistome and upper lip apparently amalgamated, but with ventral crescentic appendage possibly representing upper lip. Mandibles huge; incisors blunt, broad, fuzzy; right lacinia mobilis thin, apically trifid or humped, left lacinia mobilis broad, dome-shaped, weakly toothed; raker spines absent; molars large, weakly fuzzy and scarcely triturative on edge; palp of medium size, about as long as body of mandible, mostly concealed from oral view, article 1 elongate, article 2 with one long and one short medial setae, article 3 about 0.8 times as long as article 2, apex oblique and short, bearing 3 setae. Lower lip massive, inner lobes fully separate, large, outer plates with elongate mandibular lobes. Inner plate of maxilla 1 narrow, apex with 2 setae; outer plate with 9 spines, with tenth apicomedial spine-like cusp; palp article 2 reaching apex of outer plate, apex with 3 setae, one stout. Inner plate of maxilla 2 narrower and shorter than outer plate. Inner plate of maxilliped with 2 apical spines, 2 short dorsal and one short ventral plusetae plus smaller terminal pluseta, apex with excavation; outer plate with 11 medial spines and setae; articles 2–3 of palp apically produced, article 4 with 2 apical and one inner subapical setae.

Coxa 1 scarcely expanded distally, anterior margin weakly concave, posterior almost straight, ventral margin short, weakly convex, anterodistal corner rounded; coxa 2 grossly expanded distally, anteroventral corner rounded, posteroventral corner strongly extended posteriorly; coxae 3–4 narrow, comma-shaped, posterior margins deeply concave; coxa 4 shorter than coxa 3; ratios of widths to lengths of coxae 3–4 = 3:8 and 4:6. Long posterior setae of article 2 of gnathopods 1–2 and pereopods 1–2 = 5–5–0–0, short posteriors = 0–1–1–1, short anteriors = 3–2–2–0, long anteriors = 1– (side)–0–0–0. Gnathopods 1–2 almost identical to each other; article 5 elongate, posterior margin flat and extended, subquadrate distally, corner weakly extended, distomedial margin of article 5 with comb on both pairs, fan-combs absent, setae on posterior margin of article 5 on gnathopod 1 shorter and denser than on gnathopod 2; article 6 narrowly subovate, palm and posterior margin blending almost evenly but marked by defining spine; dactyl slightly overriding palm. Pereopod 2 slightly larger than pereopod 1; facial formula of setae on articles 4–5 = 1–1 and 3–2; article 4 of pereopod 1 with 2 groups of 3 posterior setae, pereopod 2 with groups of 3 and 2; main spine of article 5 reaching to M. 66 on article 6, apicolateral face with one spine, apicoposterior margin with 2 long spines (including main spine); article 6 with distal rows of 3 and 2 spines, no distomedial spine; dactyls elongate, bearing sharp inner acclivity forming erect thorn, no setule, apex with outer scale. Coxa 5 of ordinary familial form, posterior lobe larger and extending more deeply than anterior lobe, pointed posteroventrally; article 2 of pereopods 3–5 broad; pereopods 4–5 with anterior facial ridge; articles 4–5 of pereopods 3–4 narrow; ratio of widths of articles 2, 4, 5, 6 of pereopod 3 = 47:22:21:10, of pereopod 4 = 63:20:18:9, of pereopod 5 = 78:19:17:8; ratio of lengths of articles 2, 4, 5, 6 of pereopod 3 = 55:15:33:34, of pereopod 4 = 77:30:43:43, of pereopod 5 = 94:20:34:32; distomedial margin of article 6 on pereopod 5 combed.

Epimera 1–2 with attenuate, sharp tooth at posteroventral corner, posterior margins weakly convex; epimeron 2 with 2 ventrofacial setae in horizontal tandem; epimeron 3 expanded below, posterior margin convex, oblique, posteroventral corner subquadrate, bearing 2 ventrofacial setae in tandem.

Urosomites articulate; urosomite 1 almost flat dorsally, with 2 medium spines in crotch between uropod 1 peduncles medially, urosomite 1 almost fully concealing dorsum of urosomite 2. Peduncle of uropod 1 with 3 lateral spines, none elongate, medially with 4 spines, apicalmost stout; rami of uropods 1–2 apparently lacking nails (mostly broken off), rami of uropod 1 each with dorsal spine, rami of uropod 2 naked; peduncle of uropod 2 with one apicolateral elongate spine, medially with one apical spine, peduncles of uropods 1–2 with ragged apical comb. Uropod 3 large; peduncle with one apical spine ventrolaterally, one dorsolaterally, one small medial spine dorsally; rami submasculine, inner extending almost to M. 80 on article 1 of outer ramus; inner ramus tapering to blunt or sharp point bearing apicolateral setule, one basomedial setule; article 1 of outer ramus with one lateral spine, one apicolateral spine, one apicomedial spine, article 2 elongate, tapering to narrow truncation bearing one setule. Telson ordinary, about 1.2 times as long as wide, deeply cleft, weakly subcordate, lobes rapidly tapering to bifid apex bearing setule, no lateral acclivity, each lobe with lateral subapical setule and 2 midlateral dorsal setules on each side at M. 50.

Cuticle covered with occasional pipes, very minutely fuzzy.

OBSERVATIONS.—Juvenile “c” from type-locality: epimera and uropods similar to holotype.

HOLOTYPE.—AM, female “b,” 2.32 mm.

TYPE-LOCALITY.—SBS 4, 30 Jul 1973, off Malabar, New South Wales, Australia, 66 m, bottom unknown.

VOUCHER MATERIAL.—Type-locality, juvenile “c,” 2.22 mm (illus.).

RELATIONSHIP.—This species differs from all others described in the pair of ventral setae on epimeron 3. In terms of pereopod 5 it seems to have the closest resemblance to Urothoides makoo, but differs strongly in narrower articles 4–5 of pereopods 3–4, the longer posterior lobe on article 2 of pereopod 5, in the extended wrists of the gnathopods, shorter dactyls on pereopods 1–2, distinctive telson, and the unusually small coxa 4 and broadly expanded coxa 2, among numerous other distinctions.

MATERIAL.—AM, one sample (2).

DISTRIBUTION.—New South Wales, off Malabar, 66 m, bottom unknown.