Praedatrypaea jangamo, Poore, 2023

Poore, Gary C. B., 2023, New records, one new genus and 21 new species of Callianassidae (Crustacea, Axiidea) from the Indo-West Pacific, Memoirs of Museum Victoria 82, pp. 167-255 : 205-207

Praedatrypaea jangamo sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:801C7423-148A-

4A4A-9249-0E3D2877BA9D

Figure 27

Praedatrypaea MOZ-34.— Robles et al., 2020: figs 1, 3, 6.

Material examined. Holotype. Mozambique, off Praia de Jangamo , 24° 8.33' S, 35° 42.07' E, 406–410 m (MAINBAZA stn CC3163 ), MNHN IU-2008-10313 *# (male, 9.8 mm, without major cheliped).

Diagnosis. Antennular peduncle reaching distal margin of antennal peduncle article 4. Maxilliped 3 ischium about as long as wide; merus oval, about 1.35 times as wide as long, with tooth on convex distal margin. Chelipeds meri upper margins each unarmed. Major cheliped unknown. Uropod endopod 1.5 times as long as wide; anterior margin straight, with about 10 distal stout setae; distal-posterior margin semicircular; dorsal face with 2–4 proximal spiniform setae, another 1–3 close to anterior margin and 1–3 distally. Uropod exopod widest distally, 1.4 times as long as wide; anterior margin convex, not setose. Telson 1.2 times as long as wide, widest at strong lateral lobes at one third length; posterior margin convex, with median spine; with 1–3 pairs of spiniform setae on posterolateral margin; with 2 pairs of longitudinal rows of 2 spiniform setae. Male pleopod 1 2-articled; pleopod 2 biramous.

Description. Male. Rostrum acute, triangular in dorsal view, situated below level of dorsal carapace, half as long as eyestalks. Carapace dorsally convex, as long as pleomeres 1 and 2 combined; orbital margin almost transverse; anterolateral lobes rounded; subanterolateral margin oblique; cervical groove across 0.75 length of carapace, shallow at midpoint, almost reaching linea thalassinica. Pleon damaged; pleomere 6 with oblique shelf protruding from posteroventral margin.

Eyestalk little longer than wide, with oblique dorsal face diverging from rostrum, anterolateral margin convex, oblique, anteromedial angle rounded in dorsal view, not reaching distal margin of antennular peduncle article 1. Cornea densely pigmented, sitting in proximal part of eyestalk.

Antennular peduncle reaching distal margin of antennal peduncle article 4; article 1 visible in dorsal view; article 3 about as long as articles 1 and 2 combined; articles 2 and 3 with longitudinal ventral row of long setae. Antennal peduncle article 5 0.75 length of article 4; scaphocerite comma-shaped in dorsal view.

Maxilliped 3 ischium subrectangular, about as long as wide, crista dentata consisting of row of about 30 uneven contiguous teeth; merus oval, 0.7 length of ischium measured along outer margin, about 1.35 times as wide as long, with mesiodistal margin evenly convex, with sharp mesially directed tooth; carpus about as long as merus outer margin; propodus tapering, 1.4 times as long as greatest width; dactylus 0.9 length of propodus, elongate-oval, with dense row of short setae along flexor (lower) margin.

Major cheliped unknown.

Minor cheliped carpus-palm upper margin 0.8 carapace length. Ischium lower margin with 10 similar teeth. Merus little longer than ischium; upper margin convex, smooth; lower margin with small tooth near midpoint. Carpus dilating, 1.15 times as long as merus, 2.8 times as long as wide. Palm 0.6 length of carpus, 1.3 times long as wide; upper margin barely convex; lower margin carinate, with row of setae extending onto fixed finger; fixed finger as long as palm, cutting edge obsoletely dentate. Dactylus longer than palm, curved distally; cutting edge smooth.

Pereopod 2 merus 3.2 times as long as wide; carpus 1.4 times as long as wide; chela subtriangular; palm 1.8 times as wide as upper margin; dactylus 2.4 times as long as palm upper margin. Pereopod 3 carpus subtriangular, twice as long as wide; propodus oval, longer than wide, with evenly curved lower margin, marginal setae in groups separated by gaps, with 1 short spiniform seta; dactylus 0.7 length of propodus upper margin. Pereopod 4 missing. Pereopod 5 chelate.

Pleopod 1 uniramous, article 2 longer. Pleopod 2 biramous, endopod half as long as exopod. Pleopods 3–5 biramous, endopod 2.6 times as long as wide; appendix interna narrow, 0.15 times as long as endopod.

Uropod endopod and exopod well overreaching posterior margin of telson. Endopod almost semicircular, 1.5 times as long as wide; anterior margin straight; anterodistal margin with about 10 subdistal spiniform setae; dorsal face with 2–4 proximal spiniform setae, another 1–3 close to anterior margin and 1–3 distally (slight differences between left and right endopods). Exopod widest distally, 1.4 times as long as wide; anterior margin convex, not setose; posterior margin with about 12 falcate setae indistinguishably merged with densely setose distal margin; dorsal plate moderately differentiated from distal margin, comprising 2 or 3 rows of short and medium stiff setae merging anteriorly with similar setae on distal margin; dorsal face with short spiniform seta near anterior margin.

Telson 1.2 times as long as wide, widest at strong lateral lobes at one third length, narrowing posteriorly to rounded corner leading to posterior margin; posterolateral margin with 1–3 pairs of spiniform setae; posterior margin convex, setose, with medial spine; dorsal transverse ridge with 2 or 3 pairs of spiniform setae and long setae; dorsal surface with 2 pairs of longitudinal rows of 2 spiniform setae.

Etymology. From Praia de Jangamo, a local name in Mozambique near the type locality (noun in apposition).

Distribution. Western Indian Ocean ( Mozambique Channel); 406– 410 m.

Remarks. Praedatrypaea jangamo is known from a single male from deep water, two or three times as long as all other species. It is distinguished from other species by the broader uropodal rami and their pattern of spiniform setae.The rostrum is unusually short and the antennal article 5 longer than in other species.

Figures

Figure 27. Praedatrypaea jangamo sp. nov. Mozambique, MNHN IU-2008-10313, holotype, male, 9.8 mm: a, carapace, pleomeres 1, 2 (lateral); b, c, anterior carapace, eyestalks, antennular, antennal peduncles (lateral, dorsal views); d, telson, left uropod, right uropodal endopod; e, telson, left anterolateral margin and lobe (oblique dorsoposterior view, posterior part of telson sitting in socket); f, telson, left anterolateral margin, lobe and setae on transverse ridge (dorsal view); g, maxilliped 3 (inner view); h, maxilliped 3 ischium, merus (outer view); i, minor cheliped (right, mesial view); j, k, pereopods 2, 3; l–n, pleopods 1–3. Scale bars = 1 mm.