Urohaustorius merkanius Barnard & Drummond 1982

Urohaustorius merkanius

DIAGNOSIS.—Dorsolateral armament rows on articles 1 and 2 of antenna 1 composed of thin elements; on article 4 of antenna 2 mixing spines and setae. Armament row on article 4 of antenna 2 even. Accessory flagellum not reduced. Main flagellar articles of only terminal male antenna 1 thickened, usually aesthetascs 2 per article and usually absent on articles 1–3, article 5 of male not bulbous. Coxa 1 not larger than coxa 2, both bearing only tiny setules. Spines on dactyl of pereopod 5 set in pairs on at least 1 locus. Dactyls of pereopods 6–7 well developed. Article 2 of pereopod 7 with 2 long posteroproximal setae, sometimes a third towards midmargin, and setules. Male sternite 6 with narrow, acute, posteriorly directed ventral tooth. Epimeron 2 bearing medium tooth, with about 3 facial setae in horizontal row. Tooth of epimeron 3 medium. Inner rami of uropods 1–2 much shorter than outer rami. Dorsolateral margin of peduncle on uropod 2 with or without spines. Apicolateral corner of peduncle on uropod 3 with stout spines, outer ramus with setae, with or without spines laterally on article 1. Telson entire, distally crenulate.

ADDITIONAL CHARACTERS.—Article 5 of antenna 2 oblong in adult females, more clavate in males, peduncle of uropod 1 more than half as wide as long.

GENERAL DESCRIPTION.—In contrast to U. parnggius, the majority of adult specimens of U. merkanius with (1) more numerous spines (of medium thickness and length) on article 1 of antenna 1 (generally 5–8 elements); (2) primary flagellum of male antenna 1 with slender articles bearing only 2 aesthetascs each, and these absent on articles 1–3 (except on 1 male, P.23354, 1500 m E of Belmont Beach, NSW, presumably terminal); (3) article 4 of antenna 2 with facial armament evenly aligned; (4) dactyl of pereopod 5 broad, with spines doubled at 1 or more loci; (5) posterior margin on article 2 of pereopod 7 with fewer long setae, generally 2 (less commonly 3), confined to proximal half; (6) peduncle of uropod 1 stout and stumpy, more than half as broad as long; (7) ordinary shape of article 2 on outer ramus of uropod 3; and (8) sternal tooth on male pereonite 6 distally attenuate and acutely pointed.

DESCRIPTION OF MALE.—Holotype male “o,” 3.49 mm (Western Port; probably not terminal): Head about 70% as long as wide, rostrum about 15% as long as remainder of head. Primary flagellum of antenna 1 with 10 unthickened articles, 2 aesthetascs each on articles 4–8, 1 on article 9; accessory flagellum 7-articulate; facial formula of mixed spines and setae on article 1 of antenna 1 = 5E, 2P; on article 4 of antenna 2 = 2P, P, SSESEES–PSSESESSESESSESS; on article 5 = 4SESESEESEESESSE; spines dominant only on antenna 2; article 3 with 5 facial setae; article 5 about 68% as wide as long, 61% as long as article 4; flagellum with 9 articles. Right incisor simple, left with 2 teeth, choppers on molars with 4–5 cusps; formula on right palp article 3 = 8–1–3–1, left = 7–1–3–1. Inner plate of maxilla 1 with 1 short apical seta, 1 large apicomedial seta; outer plate with 11 spines (several with 3 side teeth instead of 2 as shown for U. pulcus.) Inner plate of maxilla 2 with 6 setae in medial row. Inner plate of maxilliped with about 6 medial setae, outer plate with 1 apicolateral seta, palp article 2 with 6 setae in facial row, article 3 with 2 setae in facial row.

Coxa 1 broadly subtriangular; coxa 2 similar but apex blunter; coxa 3 with 9 ventral setae all in posterior half, posterior margin with 2 setae both ventral; coxa 4 with 7 long ventral setae and 10 mixed posterior setae.

Setal and spine formulas on pereopod 3 = 4, 5, 2–1–1–1–1, 5 + 5 + 1 (= aberrant case, normal = 6 + 5 + 1); on pereopod 4 = 3, 5, 2–1–1–1–1, 6 + 5 + 1, posterior margin of articles 5–6 with broken row of serrations. Article 2 of pereopods 5–7 progressively with medium to sparse setal densities posteriorly, article 2 of pereopod 5 lacking mediofacial brush, dactyl with 5 spines in tandem plus 2 partners. Pereonal sternite 6 with acute midventral projection posteriorly directed (illus.). Article 2 of pereopod 7 with 3 posterior marginal setae.

Peduncular spine formulas of pleopods 1–3 = 2 and 1, 2 and 0, 2 and 1; segmental formulas = 17–12, 15–11, 15–13 (inner proliferate); basal setal formulas = 11–2–4–5, 5–0–2–0, 7–2–1–3.

Epimeron 2 with 3 setae in horizontal row.

Peduncle of uropod 1 stumpy, more than half as wide as long, with 6 setae, apicolateral corner with 1 setule; on uropod 2 with 3 apicolateral spines closely contiguous, plus 1 setule; dorsal setae = 3 and 1; setae of rami = 7–5 and 7–4, inner rami extending 65% and 42% along outer. Apicolateral corner on peduncle of uropod 3 with 4 spines, medial margin with 2 weak setae in tandem, ventromedial apical row(s) with 10 mixed setae (rows distinct, 7 and 3), spine/seta formula on lateral margin of article 1 of outer ramus = Ee–Ee–Ee; article 2 of outer ramus about 80% as wide as long, about 28% as long as article 1.

Telson about 0.95 as long as wide, entire, extreme apex flat, basally glandular; setal formula = 2P, 1, 1, P, 1, 1.

Lateral gland clusters well developed in pleonites 3–6, more weakly developed in peduncle of uropod 3.

Male “b,” 3.29 mm (Towra Point, Botany Bay, NSW): Armament of articles 4–5 of antenna 2 ordinary; formula of article 4 = PP–SE–PSSSESEESS-PSEESEESESESESS. Dactyls of pereopod 5 stout, right with 1, left with 2 spines doubled. Posterior margin of article 2 on pereopod 7 with 3 setae, confined proximally. Epimeron 2 with 3 facial setae on right, 4 on left (illus.). Peduncle of uropod 1 more than half as broad as long, with 6 lateral setae; inner ramus unusually short (only 56% as long as outer). Peduncle of uropod 2 with 3 apicolateral spines and 1 lateral spine (illus.); dorsal peduncular setae = 3 and 2; ramal setae = 7 and 4, 7 and 3. Lateral spine-seta formula on outer ramus of uropod 3 = ES, ES, Ee, Ee/ES, Ee, Ee, Ee. Telson (illus.) apically peaked, basally glandular; formula = 2P, 1, 1, P, 1, 1/2P, 1, P, 1, 1.

Male “p,” 4.05 mm (offshore, 1500 m E of Belmont Beach, 16 km S of Hunter R, NSW): Article 1 of antenna 1, formula = 5 + 2P. Article 4 of antenna 2 formula = PP–ESP–SSSEESESS–PSEESESESESESS; of article 5 = SSSE–S–ESS–EESEEESS. Dactyl of pereopod 5 stout, spine formula = 2–2–1–1–1/1–2–2–1–1–1. Article 2 of pereopod 7 with 2 proximal posterior marginal setae. Inner ramus of uropod 1 on left side unusually long, 77% as long as outer. Peduncle of uropod 2 with 1 long dorsal seta, 3 lateral and 3 apicolateral strong spines. Left and right spine-seta formula for outer ramus of uropod 3 = Ee, Ee, Ee, Ee/ES, Ee, ES, Ee, Eee. Telson tending to asymmetry at apex, basally glandular; formula = 1, 2P, 1, 1, P, 1, 1/2P, 1, 1, P, 1, 1.

Male “q,” unmeasured, 1~4 + mm (offshore 1500 m E of Belmont Beach, NSW): The only specimen of U. merkanius with thickened basal articles and many aesthetascs on main flagellum of antenna 1 and reduced accessory flagellum. Article 1 of antenna 1 with 6 spines + 2 penicillates; article 2 with 7 fine spines, all short except 2 distal; main flagellum of 12 articles, aesthetasc formula = 4, 4, 5, 4, 5, 5, 5, 4, 3, 1, 0; accessory flagellum of 7 very thin articles. Article 3 of antenna 2 with 5 setae; article 4 with normal U. merkanius arrangement of armament, facial formula = PPEEP–SSEESESESS–P–SSESEESESESESS; article 5 about 63% as wide as long, 64% as long as article 4; formula = SSESESSESEESESS. Dactylar spine formula for pereopod 5 = 1, 2, 2, 2, 1, 1/1, 3, 3, 1, 1. Article 2 of pereopod 7 with 2 posterior setae confined to proximal 1/3 of margin. Epimera 2 and 3 each with small cusp and excavate margin; epimeron 2 with 5 setae in irregular oblique-horizontal alignment and 1 ventrally, smaller, below the middle seta. Peduncular spine formulas for pleopods 1–3 = 2 and 1, 2 and 0, 2 and 0; segmental formulas = 18–14, 16–12, 15–14; basal setal formulas = 8–1–2–3, 5–1 (setule)–1–1, 6–1+2(setules)–1–3. Peduncle of uropod 2 with 2 lateral marginal spines close together, and 3 apicolateral in close tandem. Peduncle of uropod 3 with 4 spines + 1 setule on dorsolateral apex; lateral marginal formula of outer ramus on left side = eS, ES, ES, Ee, Ee; article 2 extremely short, 16% as long as article 1, and 75% as wide as long. Telson longer than wide, extreme apex flat, basally glandular; telsonic formula = 2P, 1, 1, P, 1, 1/2P, 1, 1, P, 1, 1 (very short).

DESCRIPTION OF FEMALE.—Female “f,” 3.42 mm: Like male but with following variables: Primary flagellum of antenna 1 with 9 articles, accessory flagellum with 6 articles, article 1 of peduncle with 5 thin setae plus 2 penicillate setae in armament row. Antenna 2 as shown for female of U. pulcus. article 5 about 48% as wide as long, 62% as long as article 4, facial armament formula = P–SE–PSEES–EES–PSSESESSESESESS; formula on article 5 = SEESS–EESEESESS. Spine formula on posterior margin of article 5 of pereopod 3 = 2–1–1; on article 6 of pereopod 4 = 5–4–1; otherwise like holotype. Fifth dactylar spine formula = 2, 2, 1, 1, 1/1, 2, 2, 1, 1. Brood plates thin, well setose. Uropod 1 peduncle with only 2 dorsal setae, inner ramus with only 3 setae; rami of uropod 2 with 7 and 3 setae. Ventromedial setae on peduncle of uropod 3 in rows of 11 and 1. Telson basally glandular, apical crenulation barely convex; setal formula = 2P, 1, P, 1, 1/2P, 1, P, 1, 1.

Female “a,” 3.47 mm (Lake Macquarie Salts Bay, NSW): Antennal armament in general conforming to that of Victorian specimens; article 4 of antenna 2 formula = P–EE–PSSEESESEES–PSEESESESESESS. Right and left dactyls of pereopod 5 stout, each with 2 spines doubled. Posterior margin of article 2, pereopod 7 with 2 proximal setae. Peduncle of uropod 1 more than half as wide as long; inner ramus on left side unusually long (75% as long as outer). Peduncle of uropod 2 without spines. Telson apically convex, basally glandular; formula = 2P, 1, 1, 1, 1/2P, 1, 1, P, 1, 1 (illus.).

Female “m,” unmeasured (1500 m E of Burwood Beach, NSW): With slightly depressed telsonic apex and telsonic formula as in male “p.”

Female “c,” unmeasured, and juvenile “j,” 2.35 mm (Merimbula, NSW): Both with telsonic apex depressed. Dactyl of pereopod 5 with no spines doubled on either side (juvenile only). Otherwise these conform to U. merkanius diagnosis.

DISTRIBUTION.—Victoria, Western Port, to Lake Macquarie, NSW, embayment and offshore, 0.3–28 m, fine sand, coarse sand, mud and gravel.