Comprehensive Description
provided by Smithsonian Contributions to Zoology
Tipimegus dinjerrus
DESCRIPTION OF FEMALE.—Head about 22 percent of total body length, greatest width about 75 percent of length, rostrum constricted, narrow, exceeding middle of article 2 on antenna 1. Eyes medium, clear of pigment, ommatidia sparse and scattered. Article 1 on peduncle of antenna 1 about 1.2 times as long as wide, about 2.3 times as wide as article 2, ventral margin with about 8 setules, weakly unproduced dorsal apex with 3 setules, article 2 about 1.05 times as long as article 1, with apicoventral crescent of 11 setae; primary flagellum with 11 articles, about 0.6 times as long as peduncle, bearing several long aesthetascs (articles 3–10), accessory flagellum about as long as primary flagellum, with 10 articles. Spine formula on article 4 of antenna 2 = 2–2–9–12–7, with 2 supernumerary spines, dorsal margin setose, ventral margin with 8 groups of 2–4 long to medium setae, dense ventrodistal brush of setae; article 5 about 0.55 times as long as article 4, facial spine formula = 0, dorsal margin naked, ventral margin with 5 sets of one seta each, 5 ventrodistal long to medium spine-setae, this row set facially; flagellum about 0.9 times as long as articles 4–5 of peduncle combined, with 12 articles. Mandibles with weak to medium palpar hump; right incisor with 4 teeth, left incisor with 5 humps in 2 branches; right lacinia mobilis bifid, distal branch shorter than proximal, subbifid, proximal branch simple, pointed, lacking marginal denticles; left lacinia mobilis with 4 teeth; right rakers 10 plus one rudimentary, left rakers 11; molars elongate, conical or columnar, each with one long apical spine, one short apical spine, one medium spine on side with strong nonarticulate partner; palp article 1 short, article 2 with 2 long to medium inner apical setae and 3 other shorter inner setae, and 2 outer setae, article 3 about 0.9 times as long as article 2, oblique apex with 12 spine-setae, basodorsal formula = 2. Inner plate of maxilla 1 ordinary, bearing one long subapical pluseta, 2 apicolateral shorter setae; palp article 2 with 6 apical spines and 7 submarginal and facial setae. Inner plate of maxilla 2 shorter and much narrower than outer, outer lacking apicolateral setae, inner with 9 medial setae. Inner plate of maxilliped with 2 large, thick apical spines, 7 apicofacial setae, 4 medial setae; outer plate with 14 medial and apical spines, one apicolateral seta; palp article 1 lacking apicolateral seta, article 2 with 4 groups of one each apicolateral setae, medial margin of article 2 moderately setose, article 3 with 14–16 facial setae, 6 lateral setae, nail of article 4 absent, with 3 accessory setules. Coxa 1 strongly expanded distally, anterior margin almost straight; main ventral setae of coxae 1–4 = 9–11–10–25, posteriormost seta of coxae 1–3 shortest; anterior and posterior margins of coxa 4 strongly divergent, posterior margin oblique, almost straight, posterodorsal corner sharp, posterodorsal margin ordinary, almost straight, width–length ratio of coxa 4 = 11:13. Long posterior setae of article 2 on gnathopods 1–2 and pereopods 1–2 = 6–6–7–6, long anteriors = 15(+ 6 facial)–11–20–2, short anteriors = 2–4–7–5, no others; gnathopods with thin hands broad apically, width ratios of articles 5–6 on gnathopods 1–2 = 29:26 and 27:25, length ratios = 65:52 and 65:45, palmar humps very small, palms transverse, article 5 of gnathopods 1–2 elongate, ovate, posterior margins rounded–flat. Pereopod 2 stouter than pereopod 1, especially article 4; facial setae formula on article 4 = 6 and 6, on article 5 = 5 and 6, main spine of article 5 extending to M. 75 on article 6, spine formula of article 6 = 8 + 11 and 8 + 11 plus huge middistal spine; acclivity on inner margin of dactyls of pereopods 1–2 sharp, produced as tooth, emergent setule short, midposterior pluseta short. Coxae 5–7 posteroventral seta formula = 28–26–30, composed of marginal and facial groups. Articles 4–5 of pereopods 3–4 broad, facial spine rows dense; facial ridge formula on article 2 of pereopods 3–5 = 0–1–1; width ratios of articles 2, 4, 5, 6 of pereopod 3 = 52:48:45:17, of pereopod 4 = 62:57:37:19, of pereopod 5 = 64:10:9:5; length ratios of pereopod 3 = 74:42:44:30, of pereopod 4 = 70:60:46:48, of pereopod 5 = 75:20:16:20; article 2 of pereopod 5 exceeding middle of article 5, ventrally setose, with 7 facial setae (long) and several short setae; medial apex of article 6 only on pereopod 5 finely combed; dactyls of pereopods 3–4 short. Posteroventral corner of epimeron 1 rounded, posterior margin weakly convex, setose, anteroventral face with 8 short to medium setae, midface with 5 medium setae; posteroventral corner of epimeron 2 rounded, posterior margin weakly convex, setose, facial setae = 10, in rows of 7 and 3; posteroventral corner of epimeron 3 weakly protuberant, posterior margin straight, weakly serrate, setose, ventral margin with 11 setae mainly in posterior half, 4 of these setae in 2 pairs, face with occasional submarginal seta. Urosomite 1 with 4 paired sets of setae, each side with sets of 5, ventrally with sets of 4, 3, and (2–4), articulation line complete, urosomite 1 protuberant dorsally. Rami of uropods 1–2 with articulate enlarged sharp apical nails; outer and inner rami of uropod 2 with accessory nails, continuously spinose; outer ramus of uropod 1 with 9 dorsal spines, almost continuously spinose, with small asymmetricity, inner with 6 dorsal and 3 lateral spines; outer ramus of uropod 2 with 7 dorsal spines, inner with one spine (= accessory); peduncle of uropod 1 with 3–4 apicolateral spines, medially with 3 marginal spines, peduncle of uropod 2 with 5 dorsal spines, medially with one small apical spine, apicolateral corners of peduncles on uropods 1–2 and rami lacking comb. Peduncle of uropod 3 with 17 ventral spines, dorsally lacking lateral spine (merged with ventral spines), one medial spine and setule; rami submasculine, inner extending to M. 100 on article 1 of outer ramus, apex with 3 setae, medial and lateral margins setose; article 2 of outer ramus short, 0.14, bearing 3 medium to long setae, lateralmost being medium unplumose spine, apicomedial margin of article 1 setose, lateral margin with 3 acclivities, spine formula = 2–2–2–2, setal formula = 0–0–0–1 or 0. Telson ordinary, length–width ratio = 25:28, not fully cleft, each apex of medium width, rounded, undulant, lateral acclivity shallow, weak, with lateral and medial spines separated by setule; midlateral setules diverse. Cuticle with ordinary bulbar setules mixed with pipes, surface bearing fine denticles, emergent setules branched.
OBSERVATION (female).—Article 3 of antenna 2 with 6 facial spines and setae plus one disjunct setule; rostrum much narrower than in T. thalerus.
DESCRIPTION OF MALE (subadult).—Eyes scarely enlarged; primary flagellum of antenna 1 with 10 articles, bearing long aesthetascs on articles 2–9; dorsal margin of article 4 on antenna 2 with male fuzz, spine formula = 2–10–9–5, of article 5 = 2, article 5 with 5 sets of dorsal male setae, flagellum weakly elongate, with 15 articles, calceoli absent; basofacial setal formula on article 3 of mandibular palp = 3, inner margin with 2 medium sized accessory setae; article 4 of pereopods 1–2 much thinner than in female; pereopods 3–5 and epimera similar to those of female; see illustrations for spines on uropods 1–2; spine formula on article 1 of outer ramus on uropod 3 = 1–2–2–2–2, setae = 1–1–1–1–1, setae otherwise scarcely more dense than in female, peduncle with 12 ventral spines, one dorsolateral spine; telson as in female but with sparse mediobasal denticles on each lobe.
ILLUSTRATIONS.—All parts, except those few illustrated and except for proportions and spine counts mentioned in description, like those of Tipimegus thalerus, especially epistome, mouth parts, pereopods 1–5, dactyls of pereopods 3–4, uropod 3, telson, especially article 5 of pereopod 5 and setal distribution on coxae 2–3.
HOLOTYPE.—WAM, female “w,” 8.13 mm.
TYPE-LOCALITY.—WAM 416–73, 24 Jul 1943, off Jibbon Point, New South Wales, Australia, 40 m.
VOUCHER MATERIAL.—The type-locality: male “v,” 7.85 mm (illus.) and 2 similar males.
RELATIONSHIP.—This species appears closest to T. thalerus mainly because so many minor proportions, such as those of pereopods 3–5, and the general large size of and setation densities on epimera and coxae 1–3, resemble that species rather than T. kangulun. Nevertheless T. dinjerrus differs from T. thalerus in characters it shares with T. kangulun, such as the small cuticular setules, almost continuous spination on the outer ramus of uropod 1, and the broad apices on the hand of the gnathopods. From T. kangulun, T. dinjerrus differs mainly in the short dactyls of pereopods 3–4 and the distinctiveness of the lateral spine on article 2 of the outer ramus on uropod 3. Only one female and 4 subadult males of T. dinjerrus are known; thus a wider variety of material is required to determine whether or not this species is valid.
MATERIAL.—WAM, one sample (5).
DISTRIBUTION.—New South Wales, off Jibbon Point, 40 m.
