Brolgus tavelus Barnard & Drummond 1978

Brolgus tavelus

DESCRIPTION OF MALE.—Head about 23 percent of total body length, greatest width about 70 percent of length; rostrum unconstricted, broad, elongate, evenly tapering, reaching apex of article 2 on antenna 1. Eyes medium, clear of pigment core, reddish brown. Article 1 on peduncle of antenna 1 about 1.5–1.7 times as long as wide, about 2.3 times as wide as article 2, with medial patch of fuzz, ventral margin with about 10 setules, weakly produced dorsal apex with one long seta, one setule; article 2 about 0.4 times as long as article 1, with apicoventral crescent of 3–4 setae; primary flagellum with 6–8 articles, about 0.8 times as long as peduncle, bearing calceolus on articles 1–4, long aesthetascs on articles 2–(pen)ultimate; accessory flagellum with 4–6 articles. Spine formula on article 4 of antenna 2 = 3–6–1 or 3–5–1, dorsal margin with notch bearing 3–4 spines, ventral margin with 5–6 groups of one medium or pairs of long to medium setae, 2–3 ventrodistal medium spines, articles 3–4 with dorsomedial fuzz; article 5 about as long as article 4, facial spine formula = 0–1, dorsal margin bearing 1–2 calceoli and 3 groups of 3–4 male setae, ventral margin with one setal-spine pair, subapical facial crescent of 3 medium spines and 2 short setae; flagellum elongate, flagellar formula = (17–23), (1) 2–4, 6, 8…penultimate. Mandibles with medium palpar hump; right incisor with 3 teeth and notch; left incisor with 5 humps in 2 branches; right lacinia mobilis bifid, distal branch much shorter than proximal, subbifid, proximal branch simple, with marginal denticles; left lacinia mobilis with 5 teeth plus one accessory tooth; right and left rakers 4–5 plus 0–2 rudimentaries; molars demarcated mainly by spines, each molar with 3 long spines; palp article 1 slightly elongate, article 2 with 1–2 long inner apical setae and 1–2 other short inner setae, article 3 about 0.90 times as long as article 2, oblique apex with 7–8 spine-setae, basofacial formula = 0–2. Inner plate of maxilla 1 narrower than in Brolgus mahmak, bearing one long apical pluseta, one shorter similar apicomedial seta; outer plate with only 9 spines; palp article 2 with 2 apical–lateral marginal spines and 3 submarginal setae. Inner plate of maxilla 2 shorter and narrower than outer, outer with 4 apicolateral setae, inner with pair of medial setae. Inner plate of maxilliped with one elongate feathered apical spine, 3 apicofacial setae, no medial setae; outer plate with 7–8 medial and apical spine-setae, no apicolateral setae; palp articles 1–2 naked laterally, medial margin of article 2 weakly setose, article 3 with 2–3 facial setae, one lateral seta, nail of article 4 long, with one accessory setule. Coxa 1 expanded distally, anterior margin almost straight; main ventral setae of coxae 1–4 = (8–11)–(8–10)–9–(5–6), posteriormost seta of coxae 1–3 slightly shortened; anterior and posterior margins of coxa 4 almost parallel, posterior margin slightly convex, posterodorsal corner rounded, posterodorsal margin ordinary, V-shaped, width–length ratio of coxa 4 = 14:15 or 10:11. Long posterior setae on article 2 of gnathopods 1–2 and pereopods 1–2 = 2–(0–2)–2–(2–3), short posteriors = (0–1)–0–0–0, long anteriors = (0–1)–(0–1)–0–0, short anteriors = 1–0–1–(0–1), one long facial on gnathopods 1–2. Gnathopod 1 with elongate hand, gnathopod 2 with enlarged hand; width ratios of articles 5–6 on gnathopods 1–2 = 28:43 and 26:50, length ratios = 54:97 and 45:102; palmar humps ordinary to large, palms strongly oblique; article 5 of gnathopod 1 triangular, cryptic, posterior margin short, article 5 of gnathopod 2 short, triangular. Pereopods 1–2 similar; posterior margin of article 4 on latter with longer setae, facial setae formula on article 4 = 0–0 or 1–1, on article 5 = 2–2 and 2–(2–3), main spine of article 5 extending to M. 90 + on article 6, article 5 lacking proximoposterior spines, spine formula of article 6 = 4 + 4, no middistal seta, some spines especially long; acclivity on inner margin of dactyls of pereopods 1–2 obsolescent, emergent setule almost fully immersed, midfacial pluseta long. Coxae 5–7 posteroventral setule formula = 1–2–1. Articles 4–5 of pereopods 3–4 narrow, facial spine rows sparse, facial ridge formula on article 2 of pereopods 3–5 = 0–1–1; width ratios of articles 2, 4, 5, 6 of pereopod 3 = 50:25:20:10, of pereopod 4 = 67:23:16:10, of pereopod 5 = 75:13:12:6, length ratios of pereopod 3 = 73:35:30:38, of pereopod 4 = 100:60:85:92, of pereopod 5 = 115:24:22:29; article 2 of pereopod 5 reaching middle of article 4, medial apex of article 6 combed, sigmoid. Posteroventral corner of epimeron 1 rounded, posterior margin convex, anteroventral margin with 1–3 medium setae, posteroventral face with one medium seta; posteroventral corner of epimeron 2 rounded–quadrate, posterior margin weakly convex, facial ridge extremely weak, facial setae = 2 crowded forward; posteroventral corner of epimeron 3 rounded, with setule sinus, rarely absent, posterior margin strongly convex, with 0–1 setules, ventral margin naked; epimera 1–2 with small setule on posterodorsal margin set in weak notch, epimera 2–3 with very short facial ridge or none. Urosomite 1 with lateral setule at base of uropod 1, articulation line complete; urosomite 3 unprotuberant dorsally. Rami of uropods 1–2 with articulate apical nails, bearing scale; outer ramus of uropod 1 with 2–3 dorsal spines, inner with 1–2, outer ramus of uropod 2 with 1–2 dorsal spines, inner naked; peduncle of uropod 1 with 2–3 apicolateral spines and one basofacial seta, medially with 3 marginal spines, plus special apical enlarged spine; peduncle of uropod 2 with 4–6 dorsal spines, medially with one large apical spine; apicolateral corners of peduncles on uropods 1–2 with comb, coarse dorsolaterally on uropod 1. Peduncle of uropod 3 with 6 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 2 setae, medial and lateral margins setose, article 2 of outer ramus ordinary, 0.17, bearing one long seta, apicomedial margin of article 1 with one spine and one seta, lateral margin with 3 acclivities, spine formula = 2–2–2–2 or 1–2–2–2, setal formula = 1–1–1–1. Telson elongate, length–width ratio = 16:11, not fully cleft, each apex narrow, rounded, lateral acclivity shallow, narrow, bearing ordinary lateral setule, spine next medial slightly longer or of length equal to setule, each lobe with row of denticles, midlateral setules almost alike. Cuticle with sparse, ordinary bulbar setules.

OBSERVATIONS.—Prebuccal parts moderately extended forward, epistomal region extended as rounded lobe from lateral view, epistome and upper lip fused together but with remnants of articulation line dorsally, anterior face with crescentic rugosity, ventral margin almost truncate, with tiny midhump (visible if rotated properly); lower lip as in Brolgus mahmak but mandibular lobes slightly broader apically; maxilla 1 like that of B. mahmak (but outer plate with only 9 spines), shape of inner plate slightly narrower (see illustration) and palp of different appearance (see illustration), palp with stout apical spine, thinner marginal spine and 3 setae; maxilla 2 like that of B. mahmak; maxilliped generally like that of female B. mahmak but main apical spine on inner plate almost twice as long (see illustration), bearing 3 apicofacial setae, no ventroapical seta (except for one attributed as spine), outer plate with 6 spines, article 3 of palp with 2 facial setae and one lateral seta, nail of dactyl (see illustration) much longer than in B. mahmak; coxae 1–3 as in B. mahmak, coxa 4 broader, width length ratio averaging 11:12; pereopod 4 about 1.2 times as long as in B. mahmak relative to pereopods 3 and 5; apical nails on rami of uropods 1–2 of this species and B. koongarrus with scale extensions borne on chitin of ramal body, each scale bearing free setule.

ILLUSTRATIONS.—Calceoli on dorsal margin of article 5 of antenna 2 not shown; second facial ridge on article 2 of pereopod 5 apparently artificial; head of holotype male “c” with eyes in wrong position owing to preservational defects, male “y” with presumed normal eyes and correct insertion of antenna 1; right mandibular palp of holotype abnormal in having only one long inner apical seta on article 2 and no basofacial setae on article 3; coxa 7 of holotype with setule omitted; posteroventral setule sinus on holotype epimeron 3 omitted.

HOLOTYPE.—AM, male “c,” 3.50 mm (with right uropod 3 missing).

TYPE-LOCALITY.—AM P.18125, 12 Dec 1939, Antechamber Bay, Kangaroo Island, South Australia, in net at night.

VOUCHER MATERIAL.—Type-locality, male “y,” 3.63 mm (illus.). Female unknown.

RELATIONSHIP.—The male (female unknown) of Brolgus tavelus differs from the females of B. tattersalli, B. millinus, and B. mahmak and the males of B. tattersalli and B. millinus in the telsonic armament formula, to wit, in B. tavelus the main apical spine is medial and the setule is lateral, whereas in the other three species the lateralmost element is always a spine or elongate seta. The male of B. koongarrus also has a spine as the lateral element.

This species and B. koongarrus appear to differ from the other species in the presence of a scale adjoining the apical nails on the rami of uropods 1–2. They also have only 9 spines on the outer plate of maxilla 1 in contrast to the other 3 species which bear 11 spines.

Together, B. tavelus and B. koongarrus (to follow) differ from B. mahmak in the much narrower rostrum, the bifid and distally unextended right lacinia mobilis, unbroadened distal tooth on left lacinia mobilis, presence in almost all specimens (except holotypes) of 2 long apical setae on article 2 of mandibular palp, presence of basofacial setae on article 3 of mandibular palp, absence of a stout apicomedial spine on inner plate of maxilliped (apart from normal 3 spine-setae and fine apicoventral spine found in all species of Brolgus), much longer main apical spine on article 5 of pereopods 1–2, longer article 2 of mandibular palp (longer than article 3), shape of epimeron 3, coarseness of apicolateral comb on peduncle of uropod 1, the the uropodal scales, differences in telsonic spination, and absence of spines on inner ramus of uropod 2.

MATERIAL.—AM, one sample (8).

DISTRIBUTION.—South Australia, Kangaroo Island, in net at night.