Metaphoxus tuckatuck Barnard & Drummond 1978

Metaphoxus tuckatuck

DESCRIPTION OF FEMALE (phenotype A)—Head about 16 percent of total body length, greatest width about 60 percent of length; rostrum reaching apex of article 2 on antenna 1, unconstricted, tapering evenly, apically rounded. Eyes large, with purple core in preservative surrounded by large ommatidia. Article 1 on peduncle of antenna 1 almost 1.4 times as long as wide, more than twice as wide as article 2, apicoventral margin with several setules, strongly produced dorsal apex with 3 setules; article 2 about 0.4 times as long as article 1, apicoventral corner with 2 setae, article 2 overriding article 3 weakly on medial surface; accessory flagellum shorter than primary flagellum, 3-articulate; primary flagellum 5-articulate, aesthetascs present. Spine formula on article 4 of antenna 2 = 3–3–3, proximal set with one accessory setule, spines thin, dorsal margin with 2 setae in tandem, ventral face with 5 penicillate setules, ventral margin with about 6–7 short to long setae, apex with thin spine and short seta; article 5 about 0.75 times as long as article 4, facial spine formula = 2, with one accessory setule, dorsodistal corner with 3 spine-setae, dorsal margin smooth, ventral margin with 3 single medium setae, ventrodistal apex with about 5 setae and setules; flagellum as long as article 4 of peduncle, 4-articulate. Prebuccal complex convex anteriorly, well extended forward, epistome and upper lip mostly fused together, ventral margin of upper lip weakly bisinuate. Palpar hump of mandible small; right incisor tridentate, with notch defining second tooth and accessory hump between teeth 2–3; left basically bidentate, distal branch weakly bidentate and bearing weak proximal facial hump; right lacinia mobilis flabellate, distal branch poorly defined, margin toothed, face with weak hump; left lacinia mobilis flabellate, 6-toothed: right rakers 2, left 3; molar conical, setulose; palp article 2 with subbasal seta and 4 subapical long setae on inner margin, article 3 about as long as article 2, oblique apex with 12 setae. Cones on lower lip absent, mandibular lobes of medium length, weakly attenuate and apically rounded, inner lobes cleft about one third their length. Inner plate of maxilla 1 large, ovate, naked; outer plate with 7 spines; palp exceeding apex of outer plate, bearing 2 apical and one weakly apicolateral setae. Inner plate of maxilla 2 much broader and shorter than outer plate, medial margin of inner plate with one disjunct and distinctly medial seta plus 5 other short to medium setae, outer plate with 2 apicolateral, 4 apical and one medial setae. Inner plate of maxilliped with one mediofacial spine and 2 apical spines; outer plate with 5 spines, 2 longest basal spines hidden behind inner plate; article 2 of palp with sparse, stout and short medial setae, article 3 lacking facial setae, article 4 long, apical spine of medium length, bearing 2 accessory setules, first very long. Coxa 1 distally expanded and broadly rounded anteroventrally; long setal formula of coxae 1–4 = 8–9–9–3, each with tiny additional posteroventral bulbar setule; coxa 4 quadratiform, posterodorsal excavation large to medium, L-shaped, ratio of width to length = 1:1. Gnathopod 2 scarcely stouter than gnathopod 1; long posterior setae on article 2 of gnathopods 1–2 = 3–5 and 4; gnathopods subeusirid, article 5 small and triangular but apex scarcely produced, article 6 almost slender, slightly more than twice as long as wide, palm oblique, defining hump of medium size, defining spine large, dactyl fitting palm, apex of dactyl with flake, posterior margin of article 6 with 2–3 setae, posterior corner of article 5 almost cryptic; length ratios of articles 5–6 on gnathopods 1–2 = 36:90 and 33:95, width ratios = 23:45 and 22:46. Pereopods 1–2 similar to each other; long posterior setae on article 2 of pereopods 1–2 = 4 and 5–6; article 4 with about 4 apicoanterior setae and 4 apicofacial setae on pereopod 1, 2 apicofacial setae on pereopod 2, posterior margins of articles 4–5 moderately to weakly setose, article 5 with 1, rarely 2 apicofacial setae, with long posterodistal spine slightly exceeding apex of article 6, lacking small contiguous spine at base (possibly represented by facial seta), article 6 bearing one posterior seta, 2 apicofacial setae, one long apical spine, one short spine and one seta, rows therefore composed of 2 and 2 with 2 accessory facial setae, lateral spine row composed of shorter spine plus posterior seta, (also interpreted as 3 + 2 + middle distal spine), medial row composed of longer spine and one seta, dactyl with apical flake and thin inner setule (almost appressed), apical nail not evident. Coxae 5–7 posteroventral setule formula = 1–1–1. Articles 4–5 of pereopods 3–4 thin, facial spines absent, pereopods 4–5 with one anterior facial ridge; width ratios of articles 2, 4, 5, 6 of pereopod 3 = 66:17:15:7, of pereopod 4 = 80:19:13:8, of pereopod 5 = 92:13:11:6, length ratios of pereopod 3 = 78:24:24:28, of pereopod 4 = 95:52:47:45, of pereopod 5 = 115:21:23:18; article 2 of pereopod 5 extending to apex of article 4, posterior margin with small setule acclivities, ventral margin with setule scallops; apex of article 6 finely combed. Epimeron 1 with weak facial ridge, absent on epimeron 2, each with rounded–quadrate posteroventral corner and convex posterior margin, each bearing midsetule; epimeron 3 with weak posteroventral tooth and sinus bearing setule, posterior margin deeply convex, bearing 2 setule notches, epimeron 2 with one facial seta, rarely with 2 in horizontal tandem. Urosomite 1 ventrally naked, weakly produced dorsally and bearing one setule. Peduncle of uropod 1 with tiny basofacial seta, each apex of peduncle with one medium spine, medial margin with one spine, rami of uropods 1–2 naked dorsally, inner rami of uropods 1–2 and outer ramus of uropod 2 with apical flake, inner ramus of uropod 1 with small mediobasal spinule, outer ramus of uropod 1 slightly shortened, thinner and more curved than inner ramus, uropod 2 with 2–3 dorsolateral spines on peduncle, medial apex with one spine, apex of peduncle on uropods 1–2 with lateral comb. Uropod 3 of medium length, peduncle with 4 long ventrolateral spines, medially with one short spine; rami feminine, inner ramus extending to M. 100 on article 1 of outer ramus, apex with immersed setule, article 2 of outer ramus elongate, 0.50, bearing 2 apical setules, margins naked, lateral apex of article 1 with 2 spines, medial apex with one spine. Telson elongate, length–width ratio about 16:11, apices tapering, narrow, weakly excavate, each bearing medium spine and small apicolateral setule, dorsal pair of plusetules weakly diverse, near middle of each lobe, almost directly centered. Bulbar setules of cuticle extremely sparse.

DESCRIPTION OF MALE (phenotype A).—Eyes much larger than those of female, causing lateral protrusion of head. Article 1 of antenna 1 with medial patch of fuzz, disparity in length of flagella greater than in female; primary flagellum bearing calceolus (6-chambered) on each of articles 1–3. Spine formula on article 4 of antenna 2 peduncle = 4–3–3, articles 3–4 with dorsomedial fuzz, article 5 with one dorsal calceolus and 2 groups of stiff male setae, ventrodistal margin poorly setose; flagellar formula = 24, 1–3, 5, 7…23. Apex of mandibular palp with 10 setae. Long posterior setae on article 2 of gnathopods 1–2 and pereopods 1–2 = 2–(1–2)–2–3; article 6 of gnathopods slightly more elongate than in female. Long setae on coxae 1–4 = (7–8)–8–(7–8)–3; coxa 4 smaller in relation to coxae 1–3 than in female and very slightly narrower than in female. Article 4 of pereopods 1–2 with 3–4 and 0 apicofacial setae. Article 2 of pereopods 3–5 narrower than in female. Epimera enlarged, epimeron 2 with 0–1 facial seta, epimeron 3 with 3 posterior setules besides one at ventral corner. Urosome smaller than in female. Apicomedial corner of peduncle on uropods 1–2 with pair of spines in largest male, only one spine in smaller male. Rami of uropod 3 masculine, inner reaching only to M. 90 on article 1 of outer ramus, medial margins of rami setose. Telson scarcely more elongate than in female, with basal patches of dorsal denticles.

VARIATION (male phenotype A).—One outer plate on maxilliped of male “a” bearing 4 spines of stout kind.

ILLUSTRATIONS (phenotype A).—Specimens poorly preserved, heads of males especially difficult to interpret; dorsal view of male “c” head reconstructed and one damaged eye omitted; anterior lobe of coxa of pereopod 4 on male “c” omitted (damaged); dactyls of pereopods 1–2 with apical flake pulled away from dactyl in illustration, flake often closely appressed to dactyl in many specimens; 2 facial setae on epimeron 2 of male “a” represented only by holes, setae broken away.

HOLOTYPE.—NMV, female “b,” 3.46 mm, phenotype A.

TYPE-LOCALITY.—PPBES 919/4, 18 Nov 1971, Port Phillip Bay, Victoria, Australia, 6 m, silty sand.

VOUCHER MATERIAL (phenotype A).—Type-locality: male “a,” 3.11 mm (illus.); male “c,” 2.82 mm (illus.); female “u,” 3.05 mm (illus.).

DIAGNOSIS OF PHENOTYPE B.—Ommatidia of ordinary medium size; mandibular palp article 2 with only 2–3 long inner apical setae; epimeron 2 with 1–4 setae; male right lacinia mobilis poorly serrate.

DISTRIBUTION.—Victoria: Western Port and Port Phillip Bay, 0–24 m and neritic, sand, muddy sand, sand and gravel, clay, silty clay, often heavy seagrass cover.