Discias brownae

Discias brownae

MATERIAL EXAMINED.—AM-P33772, holotype, 1 , CL 3.2 mm, Green Point, Port Jackson, NSW, 33°50′S, 151°19′E, 9.8 m, coll. A. Kuiter, 24 Jun 1978. AM-P33773, allotype, 1 ovigerous , CL 4.0 mm, east of North Head, Port Jackson, NSW, 33°49′S, 151°18′E, 32.9 m, coll. Australian Museum Shelf Benthic Survey, 23 May 1972. AM-P24444, paratypes, 1 , CL 3.2 mm, 1 , CL 2.5 mm; AM-P24447, paratypes, 1 , CL 2.9 mm, 1 , CL 3.1 mm; AM-P24448, paratype, 1 , CL 2.6 mm; AM-P24450, paratype, 1 , CL 2.6 mm; AM-P24451, paratypes, 2 , CL 2.8 and 3.3 mm; AM-P24453, paratype, 1 , CL 2.9 mm; east of North Head, Port Jackson, NSW, 33°49′S, 151°18′E, 19.8 m, from sponge Teichonella labyrinthica Ridley, coll. Australian Museum Shelf Benthic Survey, 19 Feb 1973. AM-P24449, 1 damaged specimen, east of North Head, Port Jackson, NSW, 33°49′S, 151°18′E, 19.8 m, from sponge Polymastia cratica, coll. Australian Museum Shelf Benthic survey, 19 Feb 1973. AM-P24452, paratypes, 4 , CL 2.4, 2.6, 2.9, and 2.9 mm, 2 , CL 2.2 and 2.7 mm; AM-P24454, paratype, 1 , CL 2.9 mm, east of North Head, Port Jackson, NSW, 33°49′S, 151°18′E, 32.9 m, coll. Australian Museum Shelf Benthic Survey, 23 May 1972. AM-P24455, paratype, 1 , CL 4.1 mm, Long Reef, NSW, 33°44′S, 151°19′E, 32 m, coll. Australian Museum Shelf Benthic Survey, 28 May 1972. USNM 189096, paratypes, 4 , CL 2.8, 2.9, 3.0, and 3.1 mm, 3 , CL 2.9, 3.0, and 3.2 mm, Green Point, Port Jackson, NSW, 33°50′S, 151°17′E, 9.8 m, coll. A Kuiter, 24 Jun 1978.


DIAGNOSIS.—Rostrum lanceolate, apically acute, lateral margins serrate. Carapace shallowly pitted. Middorsal spine present on posterior margin of abdominal segment 2. Telson with 3 pairs of spines on posterior margin. Antennal scale lacking distolateral tooth. Mandibular palp 2-segmented, distal setose segment markedly wider than proximal segment. Outer uropodal ramus with lateral margin entire.

DESCRIPTION.—Carapace and abdominal integument shallowly pitted. Carapace with strong marginal antennal spine; anteroventral corner rounded. Rostrum dorsoventrally flattened, apically acute, with middorsal narrowly rounded ridge just extending onto carapace, widest at about midlength, margins with 18–20 fine serrations extending onto supraorbital margin. Pleura of pleonites 1 and 2 ventrally almost straight, anterior and posterior corner rounded; pleura 3–5 evenly rounded; abdominal segment 2 with strong middorsal spine on posterior margin; abdominal segment 3 not hooded; abdominal segment 6 about one-fifth longer than segment 5. Telson tapering to almost truncate posterior margin; with 2 pairs strong dorsolateral spines; posterior margin with 3 pairs of spines and minute median point.

Basal antennular peduncle segment with strong apically acute stylocerite having outer margin convex; distal margin produced dorsally into rounded lobe; peduncle reaching almost to apex of scaphocerite; segment 2 about one-third length of basal segment; segment 3 produced distomesially into lobe; dorsolateral flagellum with swollen proximal section of about 12 articles bearing clusters of aesthetascs.

Scaphocerite about 2½ times longer than wide, widest at midlength, distal margin truncate, lacking distolateral tooth; peduncle segment 2 with small spine on mesial margin.

Mandibular palp 2-segmented, distal segment oval, broader than proximal segment, with 5 setae; incisor process triangular, with 1–3 tiny spines on dorsal edge, 3 on ventral edge; molar process produced-triangular, with 9 relatively elongate spines and few small spines on distodorsal margin, about 15 shorter spines on distoventral margin.

Maxilla 1 with proximal endite rounded, distal endite more elongate, distally rounded; both endites bearing numerous setae-spines; palp with slight indication of bifurcation, bearing 3 setae.

Maxilla 2 with proximal endite truncate, smaller than and not extending mesially as far as 2 distal endites; latter both broad, with numerous setae-spines on mesial margin; palp moderately elongate, with single terminal seta; scaphognathite extending well beyond palp, broader distally, entire free margin bearing plumose setae.

Maxilliped 1 with broadly bilobed setose endite; palp digitiform, nonsetose; exopod bearing 4 distal setae, extending beyond broadly rounded setose caridean lobe; epipod bilobed.

Maxilliped 2 pediform, distal segment narrow, set obliquely on broad penultimate segment, both distal segments bearing fringed spines; antepenultimate segment short, third segment subequal to penultimate segment in length; exopod extending well beyond antepenultimate segment; epipod bilobed.

Maxilliped 3 5-segmented, distal segment of endopod widening to about two-thirds of length, then tapering to apex, bearing about 13 marginal spines; penultimate segment half length of terminal segment; latter subequal in length to antepenultimate segment; basal segment with spine-like process and small curved epipod; exopod extending beyond base of third endopodal segment.

Pereopod 1, dactylus subcircular, with strong distal spine near start of hyaline “cutting” margin; fixed finger of propodus with retrorsed immobile spine apically, and strong serrated spine on outer margin.

Pereopod 2 reaching to about midlength of propodus of pereopod 1; dactylus somewhat flattened and hollowed, bearing 2 large distal spines plus row of 12 smaller marginal spines; propodus with distal lobe forming fixed finger bearing row of 12 curved spines; carpus short, about one-sixth length of ischiomerus; exopod reaching to carpus.

Pereopods 3 and 4 similar, 3 slightly longer than 4; unguis about half length of dactylus; propodus about 2½ times length of dactylus, with 6 small spines on posterior margin; carpus slightly more than half propodal length, with strong articulated spine on outer surface; merus subequal in length to three distal segments together, bearing 3 strong spines on posterior margin; ischium about one-fifth of merus (measured along anterior margin), with 2 strong posterior spines; exopod reaching to distal half of merus.

Pereopod 5 with 3 distal segments showing progressive twisting, dactylus flexed through 180°, with small spine on (new) dorsal surface, unguis entire, propodus almost 4 times length of dactylus, with 7 groups of slender fringed spines on posterior margin; carpus with single posterodistal spine; merus with 4 spines, proximal spine posterior, following 3 spines becoming progressively lateral; ischium with 3 posterior spines; exopod reaching to distal end of merus.

Pleopod 1 in male, endopod oval, with 4 distal plumose setae. Pleopod 2 in male, endopod bearing narrowly elongate appendix masculina with 3 distal setae; appendix interna three-fourths length of appendix masculina, narrowly elongate, with 4 terminal hooks.

Outer uropodal ramus with fixed spine on entire lateral margin at about one-eighth of total length from apex, longer articulated spine internal to fixed spine; inner uropodal ramus barely extending beyond telsonic apex; uropodal basis lacking spines.