Birubius lorus Barnard & Drummond 1978

Birubius lorus

DESCRIPTION OF FEMALE.—Head about 17 percent of total body length, greatest width about 65 percent of length; rostrum constricted, narrow, almost reaching middle of article 2 on antenna 1. Eyes large, mostly occluded with pigment. Article 1 on peduncle of antenna 1 about 1.3 times as long as wide, about 2.2 times as wide as article 2, ventral margin with about 9 setules, unproduced dorsal apex with 3 setules; article 2 about 0.9 times as long as article 1, with ventral cycle of 4–5 setae; primary flagellum with 11 articles, about 1.1 times as long as peduncle, bearing long aesthetascs; accessory flagellum with 7 articles. Spine formula on article 4 of antenna 2 = 1–3–4–4 or 1–3–4–3, dorsal margin with notch bearing 3 setae, ventral margin with 5 groups of 1–2 long to medium setae, one ventrodistal medium spine; article 5 almost 0.85 times as long as article 4, facial spine formula = 1–2, dorsal margin bearing 2 sets of short setae, ventral margin with 4 sets of 1–2 long to short setae, 2 ventrodistal long to medium spines and setae; flagellum about 1.4 times as long as articles 4–5 of peduncle combined, with 12 articles. Mandibles with medium palpar hump; right incisor with 4 teeth; left incisor with 6 teeth; right lacinia mobilis bifid; distal branch shorter than proximal, flabellate, subtrifid, denticulate, with one facial hump, proximal branch simple, pointed, with marginal denticles or facial humps; left lacinia mobilis with 4 teeth, middle teeth shortened; right rakers 5–6; left rakers 5–6; molar in form of bulbous hump, right molar with 5 primarily long spines plus one spine strongly disjunct, left molar with 10 primarily long spines, no spine disjunct; palp article 1 short, article 2 with one short inner apical seta and 2 other shorter inner setae, article 3 about 1.2 times as long as article 2, oblique apex with 9–10 spine-setae, basofacial formula = 1–1 or 0–1. Inner plate of maxilla 1 large, bearing one long apical pluseta, one similar apicomedial seta, 2 apicolateral much shorter setae; palp article 2 with 5 apicalmedial marginal spines and 5 submarginal setae. Plates of maxilla 2 extending subequally, outer scarcely broader than inner, outer with 2 apicolateral setae, inner with no medial setae. Inner plate of maxilliped with 3 large, thick apical spines, 3 apicofacial setae, 4 medial setae; outer plate with 7 medial and apical spines, one apicolateral seta; palp article 1 with apicolateral spine, article 2 with 4 lateral setae, medial margin of article 2 moderately setose (naked apically), article 3 scarcely protuberant, with 5 facial setae, 3 lateral setae, nail of article 4 long, with 2 accessory setules. Coxa 1 not expanded distally, anterior margin almost straight; main ventral setae of coxae 1–4 = (10–13)–10–(4–5)–3, posteriormost seta of coxae 1–3 shortened; anterior and posterior margins of coxa 4 strongly divergent, posterior margin very oblique, convex, posterodorsal corner subsharp, posterodorsal margin short, undulant, width-length ratio of coxa 4 = 9:10. Long posterior setae on article 2 of gnathopods 1–2 and pereopods 1–2 = 3–4–4–(5–6), long anteriors = 7–(11–12)–0–0, short anteriors = 1–1–4–1. Gnathopods thin; width ratios of articles 5–6 on gnathopods 1–2 = 28:28 and 29:30, length ratios = 78:61 and 75:58; palmar humps small, palms weakly oblique; article 5 of gnathopods 1–2 elongate, ovate, posterior margin rounded-flat, long. Pereopod 2 slightly stouter than pereopod 1, especially article 4; facial setae formula on article 4 = 5 and 6, on article 5 = 4 and 6; main spine of article 5 extending to M. 100 on article 6, article 5 with one proximoposterior spine; spine formula of article 6 = 3 and 5 or 4 and 5 plus middistal seta, some spines especially long; acclivity on inner margin of dactyls of pereopods 1–2 sharp, produced as tooth, emergent setule long, midfacial pluseta long. Coxae 5–7 posteroventral setule formula = 1–1–1. Articles 4–5 of pereopods 3–4 of ordinary width, facial spine rows dense to moderately developed, facial ridge formula on article 2 of pereopods 3–5 = 1–2–2; width ratios of articles 2, 4, 5, 6 of pereopod 3 = 44:42:40:21, of pereopod 4 = 60:38:25:12, of pereopod 5 = 61:23:20:9, length ratios of pereopod 3 = 77:33:42:40, of pereopod 4 = 82:49:38:46, of pereopod 5 = 87: 21:20:23, article 2 of pereopod 5 almost reaching apex of article 4; medial apex of article 6 deeply combed and bearing 4 digital processes. Posteroventral corner of epimeron 1 rounded-quadrate, posterior margin convex, corner with setule, anteroventral margin with 3–7 medium setae, posteroventral face with 2 long setae; posteroventral corner of epimeron 2 rounded-quadrate, with setule, posterior margin convex, facial setae = 9–10, posteriormost pair set vertically; posteroventral corner of epimeron 3 weakly and broadly protuberant, with setule sinus, posterior margin straight, with 7 setule notches, ventral margin with 3–4 submarginal setae mainly posterior. Urosomite 1 with lateral horizontal row of 5–11 setae, articulation line complete; urosomite 3 unprotuberant dorsally. Rami of uropods 1–2 with articulate enlarged apical nails, inner ramus of uropod 1 with two accessory nails, outer ramus of uropod 1 with 3–4 dorsal spines, inner with one, outer ramus of uropod 2 with 1–2 dorsal spines, inner with one dorsomedial spine; peduncle of uropod 1 with 2 apicolateral spines, and 1–3 basofacial setae, medially with 3 marginal setae and spines, apicalmost an enlarged spine; peduncle of uropod 2 with 4 dorsal spines, medially with one large, apical spine. Peduncle of uropod 3 with 5 ventral spines, dorsally with one lateral spine, one medial spine; 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 ordinary, 0.17, bearing 2 medium setae, medial margin of article 1 with 4 setae, lateral margin with 4 acclivities, spine formula = 0–1–1–1–1, setal formula = 1–1–1–1–1. Telson long, length–width ratio = 6:5, almost fully cleft, each apex wide, rounded, lateral acclivity shallow, weak, bearing short ordinary lateral setule, spine next medial of length equal to setule, midlateral setules diverse. Cuticle with ordinary bulbar setules of varying sizes closely packed with pipes and horseshoes, surface bearing fine striations in form of linear fingerprint pattern, emergent setules ordinary.

DESCRIPTION OF MALE.—Only known specimen broken, missing urosome and epimeron 3. Rostrum narrower than in female. Eyes very large, forming weak lateral bulges. Article 2 of antenna 1 with 5 ventral setae; primary flagellum with 11 articles, one calceolus each on articles 1–8, one aesthetasc strongly developed on articles 9 and 10; accessory flagellum with 7 articles. Facial spine formula on article 4 of antenna 2 = 3–4–4, on article 5 = 2 plus 1–3 accessory setules (varying right and left), article 5 with 6 dorsal sets of male setae and 2–6 calceoli, ventrodistal apex with 2 thin spines and one setule; flagellar formula = 23 (broken), 1–2–3–4, 6, 8…22. Right rakers 6 plus 1–2 rudimentaries; left rakers 7 plus one rudimentary; right molar with 7 spines plus one weakly disjunct spine; left molar with 6 spines and one rudimentary spine, none disjunct; basofacial setal formula of article 3 on mandibular palp = 1–2. Inner plate of maxilliped with only 2 apical spines. Coxa 4 like that of female but smaller in relation to coxa 1; ventral setal formula of coxae 1–4 =(10–11)–(7–8)–5–3. Long posterior setae on article 2 of gnathopods 1–2 and pereopods 1–2 = 1–(1–3)–3–3, long anteriors = (5–6)–8–0–0, short anteriors = 1–1–3–1, no others. Articles 4–5 of pereopods 1–2 thinner than in female, especially pereopod 1. Article 2 of only pereopod 3 narrower than in female, articles 4–5 of pereopod 3 also narrower, article 4 of pereopod 4 slightly broadened; pereopod 5 larger relative to pereopod 3 than in female. Epimera 1–2 (3 unknown) broadened; setal formulas, epimeron 1 anteroventral = 5, posteroventral = 2, epimeron 2 facial = 8. Cuticle with mainly bulbar setules and their rudiments, pipes and horseshoes obsolescent, striations strong on pereopods 3–5 and epimera.

HOLOTYPE.—Figures herein presented of female “a,” 4.60 mm. (The holotype is designated as the figures because during placement of parts of that specimen in its depository vial a few parts of the holotype of Birubius eleebanus were mixed into the vial; during attempts to segregate the mixture the telson and one maxilla 2 of B. lorus were lost; one maxilla 2 of B. eleebanus may be deposited in this vial as this mouthpart in the two species is indistinguishable; the holotype specimen may therefore be confounded but designation of the figures ameliorates the problem. No other specimen is as desirable as this for designation as a holotype.)

TYPE–LOCALITY.—EBS 363, 10 Jul 1973, Lake Macquarie, Salt's Bay, New South Wales, Australia, 0.3 m, coarse sand.

VOUCHER MATERIAL.—Type-locality: female “b,” 4.00 mm; female “c” 3.90 mm; female “d,” 3.93 mm; male “u,” broken, true length unknown (illus.).

RELATIONSHIP.—The B. lorus-nammuldus (2–3) group of species is very close to B. panamunus (1) but differs in the absence of a fully facial oblique row of setae, in the smaller tooth on epimeron 3, and in the more trapezoidal coxa 4.

Birubius gallangus (10) has a simple distal branch on the right lacinia mobilis, ordinary gnathopodal hands and lacks long setae on coxa 4.

MATERIAL.—EBS, 4 samples (14).

DISTRIBUTION.—New South Wales, Lake Macquarie, Salt's Bay, 0.3 m, coarse sand.