Comprehensive Description
provided by Smithsonian Contributions to Zoology
Birubius quearus
DESCRIPTION OF MALE.—Head about 19 percent of total body length, greatest width about 70 percent of length; rostrum scarcely constricted, broad, short, almost reaching middle of article 2 on antenna 1. Eyes large, clear of pigment. Article 1 on peduncle of antenna 1 about 1.2 times as long as wide, about twice as wide as article 2, ventral margin with about 21 setules, weakly produced dorsal apex with 4 setules; article 2 about 0.9 times as long as article 1, with midventral cycle of 5 setae; primary flagellum with 11 articles, about 0.95 times as long as peduncle, bearing aesthetascs and one calceolus each on articles 1–7; accessory flagellum with 6 articles, only half as long as primary flagellum. Spine formula on article 4 of antenna 2 = 3–4–3, dorsomedial margin of articles 3–4 bearing fuzz, ventral margin with 5 groups of 1–2 long to short setae, one ventrodistal long spine; article 5 about 1.1 times as long as article 4, facial spine formula = 2–2, dorsal margin bearing 4 sets of male setae (not visible in illustration) and 3 calceoli, ventral margin with 3 sets of 1–3 medium to short setae, 2 thin ventrodistal long spines and one setule; flagellum elongate, flagellar formula = (31–32), 1–5, 7, 9…29 or 1–6, 8, 10…30. Mandibles with medium palpar hump; right incisor with 3 teeth; left incisor with 4 humps in 2 branches; right lacinia mobilis bifid, very short and broad, distal branch much shorter than proximal, distal branch narrow, gaping, proximal branch simple, pointed; left lacinia mobilis with 4 teeth, middle teeth shortened; right rakers 3 plus one rudimentary; left rakers 4 plus one rudimentary; molar in form of elongate plaque, bulbous, each molar with 4 primarily medium spines, none disjunct, no plume; palp article 1 short, article 2 with one long inner apical seta and 2 other short inner setae, article 3 about 1.25 times as long as article 2, oblique apex with 8 spine-setae, basofacial formula = 2–2. Inner plate of maxilla 1 ordinary, bearing one medium simple pluseta, one similar apicomedial seta, 2 apicolateral slightly shorter setae; palp article 2 with 3 apicalmedial marginal spines and 3 submarginal setae all highly distad, palp elongate. Plates of maxilla 2 extending equally, thin, of equal breadth, outer with 4 apicolateral setae, inner with 4 medial setae to base. Inner plate of maxilliped with 2 large, thick apical spines, 2 apicofacial setae, 3–4 medial setae; outer plate with 9 medial and apical spines, 5 apicolateral setae; palp article 1 with one apicolateral seta, article 2 with one apicolateral seta, medial margin of article 2 moderately to weakly setose, article 3 unprotuberant, with 2 facial setae, one lateral seta, nail of article 4 medium, with 2 accessory setules. Coxa 1 scarcely expanded distally, anterior margin almost straight; main ventral setae of coxae 1–4 = 9–9–9–11, short, posteriormost seta of coxae 1–4 shortened; anterior and posterior margins of coxa 4 weakly divergent, posterior margin oblique, straight, posterodorsal corner sharp, posterodorsal margin short, straight, width-length ratio of coxa 4 = 32:37. Long posterior setae on article 2 of gnathopods 1–2 and pereopods 1–2 = 3–4–3–6, long anteriors = 4–5–1–0, short anteriors = 1–1–2–2, no others. Gnathopods ordinary; width ratios of articles 5–6 on gnathopods 1–2 = 25:30 and 25:31, length ratios = 62:59 and 54:56; palmar humps ordinary, palms oblique; article 5 of gnathopod 1 weakly elongate, ovate, posterior margin rounded; article 5 of gnathopod 2 ovate, posterior margin rounded, almost lobate. Pereopods 1–2 similar; facial setae formula on article 4 = 7 and 6, on article 5 = 5–6 and 6; main spine of article 5 extending to M. 100 on article 6, article 5 lacking proximo posterior spines; spine formula of article 6 = 3 + 4 and 3 + 4 plus middistal seta; acclivity on inner margin of dactyls of pereopods 1–2 weak, emergent setule long, midfacial pluseta ordinary. Coxae 5–7 posteroventral setule formula = 4–5–1. Articles 4–5 of pereopods 3–4 of ordinary width, facial spine rows moderately developed, facial ridge formula on article 2 of pereopods 3–5 = 0–2–2; width ratios of articles 2, 4, 5, 6 of pereopod 3 = 40:30:32:16, of pereopod 4 = 56:28:23:9, of pereopod 5 = 78:20:19:5, length ratios of pereopod 3 = 62:25:27:33, of pereopod 4 = 78:45:44:45, of pereopod 5 = 104:27:23:18; article 2 of pereopod 5 exceeding apex of article 4, ventral setules large and numerous; article 5 with enlarged posteroventral spine; medial apex of article 6 smooth, bearing 2 digital processes. Posteroventral corner of epimeron 1 rounded, posterior margin deeply convex, with 2 setules, anteroventral margin with 6–7 medium setae, posteroventral face with 2–3 long setae; posteroventral corner of epimeron 2 rounded-quadrate, posterior margin convex, with 2–3 setules, facial setae = 12–13, occasional pairs set vertically or not; posteroventral corner of epimeron 3 with medium tooth, posterior margin weakly convex, scalloped, with 4 setule notches, ventral margin with 6–7 setae mainly anterior, occasional pair set vertically; epimera 1–3 with setule on posterodorsal margin set in weak notch. Urosomite 1 with 2 ventral setules at base of uropod 1, articulation line complete; urosomite 3 protuberant dorsally. Rami of uropods 1–2 with articulate enlarged long sharp apical nails, outer ramus of uropod 1 with 5–6 dorsal spines, inner with 2, outer ramus of uropod 2 with 4 dorsal spines, inner with none; peduncle of uropod 1 with 3 apicolateral spines and 6 basofacial setae, medially with 5 marginal spines plus apical enlarged spine; peduncle of uropod 2 with 13 dorsal spines, medially with one small apical spine. Peduncle of uropod 3 with 2 ventral spines, dorsally with one lateral spine, one medial setule; rami masculine, 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, 0.12, bearing 2 long setae, apicomedial margin of article 1 setose, lateral margin with 5 acclivities, spine formula = 0–0–1–1–1–1, setal formula = 1–1–1–1–1–1. Telson long, length-width ratio = 7:6, almost fully cleft, each apex wide, rounded, lateral acclivity narrow, weak, bearing short lateral setule, spine next medial of length equal to setule, each lobe with long dorsal row of denticles, midlateral setules diverse. Cuticle with ordinary bulbar setules surrounded by plaques forming clear spaces on surface, bearing fine striations in form of linear fingerprint pattern, emergent setules plumose.
DESCRIPTION OF JUVENILE (juvenile “j,” 3.1 mm).—Female facies. Article 2 of antenna 1 shorter than in male, with 4 ventral setae; primary flagellum 7-articulate; accessory flagellum 4-articulate. Article 4 of antenna 2 with facial spine formula of 1–3–4–2, of article 5 = 2–2, distal apex with 3 long to medium spines, flagellum 7-articulate. Mandibles as in male, basofacial setal formula on article 3 = 0–1, apex with 6 spine-setae. Long setal formula on coxae 1–4 = 6–6–6–7; posterodistal corner of coxa 4 rounded. Article 5 of gnathopod 1 slightly more elongate than in male. Pereopod 5 with 8 elongate ventral setae on article 2, no enlarged spine on article 5. Setal formulas on epimera, anteroventral epimeron 1 = 2, posteroventral = 1, posterior = 1–2 setules, posteroventral corner with small sharp tooth, epimeron 2 facial = 6–7, posteroventral = 1, epimeron 3 ventral = 2, posterior = 2 long setules, epimeron 1 with posterodorsal setule, epimera 2–3 with long posterodorsal seta. Spine formulas on uropods, peduncle of uropod 1 = 2, of uropod 2 = 4, outer rami of uropod 1 = 3, of uropod 2 = 2, inner rami of uropod 1 = 1, of uropod 2 = 0, ventral of uropod 3 peduncle = 4, basofacial setae of uropod 1 = 4, spine formula on outer ramus of uropod 3 = 1–2–2 (elongate), no setae. Apical spines of telson elongate but setules also elongate. Eyes not apparent, probably destroyed in preservative.
OBSERVATIONS.—The juvenile adds only a few points to the probable female morphology: the elongate ventral setae on article 2 of pereopod 5 and the posteroventral points on epimera 1–2; otherwise the female is suspected to have the standard female morphology of eyes, epimera, uropod 3.
ILLUSTRATIONS.—Following unfigured parts like those of B. babaneekus (16): antenna 1 but article 2 more elongate and with more ventral setules on article 1, maxillae 1–2, maxilliped except article 4 as described, coxae, (except setae much shorter), gnathopods, pereopods 1–2, pereopod 3 (except as partially illustrated). Following parts like B. gelarus (17): upper lip, pereopod 4. Dorsal male setae on article 5 of antenna 2 not shown (rotated behind); male epimeron 3 showing 7 ventral setal holes, eighth hole set vertically above showing position of seta 7 on right epimeron, latter bearing 6 ventral setae and one disjunct seta; pereopod 3 enlarged 1.1 times over pereopod 5.
HOLOTYPE.—NMV, male “b,” 5.0 mm.
TYPE-LOCALITY.—CPBS A4(T)/1, 10 Oct 1964, Western Port, Victoria, Australia, 9 m.
VOUCHER MATERIAL.—CPBS 51N/1, juvenile “j,” 3.1 mm (illus.).
RELATIONSHIP.—This species differs from either or both B. babaneekus (16) and B. gelarus (17) in the much smaller tooth of epimeron 3, the large setae on the inner plate of maxilla 1 and the presence of only 4 spines on the molars.
MATERIAL.—CPBS, 2 samples from 2 stations (2).
DISTRIBUTION.—Victoria, Western Port, 9–14 m.
