Praedatrypaea ningaloo, 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 : 214-215

Praedatrypaea ningaloo sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:9B78B4B5-0385-

4AB5-AF1D-82F8C664CA6E

Figure 32

Callianassa sp. MoV 4966.— Poore et al., 2008: 94.

Material examined. Holotype. Australia, North West Shelf , off Ningaloo North, 21.9781° S, 113.837° E, 106 m ( CSIRO stn SS10/2005/162), NMV J53459 (female, 4.4 mm).

Diagnosis. Antennular peduncle reaching midpoint of antennal peduncle article 5. Maxilliped 3 ischium about 1.3 times as long as wide; merus oval, about 1.5 times as wide as long, with tooth on convex distal margin. Chelipeds meri upper margins each unarmed. Major cheliped merus lower margin without spine at midpoint; carpus 2.3 times as long as wide; palm 1.7 times as long as carpus, 1.3 times as long as wide; fingers, cutting edges with obsolete teeth. Uropod endopod 1.4 times as long as wide; anterior margin straight, with 4 distal spiniform setae; distal-posterior margin evenly curved; dorsal face with curved row of 10 spiniform setae close to anterior margin, 2 more near posterodistal margin. Uropod exopod ovate, truncate distally, 1.7 times as long as wide; anterior margin convex, setose. Telson 1.1 times as long as wide, widest at strong lateral lobes at one-third length; posterior margin convex, with median spine; with 2 pairs of spiniform setae on posterolateral margins. Male pleopods 1, 2 unknown.

Description. Female. Rostrum acutely triangular in dorsal view, situated below level of dorsal carapace, 0.7 length of eyestalks. Carapace dorsally flat, as long as pleomeres 1, 2 combined; orbital margin oblique; anterolateral lobes rounded; subanterolateral margin oblique; cervical groove across 0.8 length of carapace, shallow at midpoint, almost reaching linea thalassinica.

Eyestalk about as long as wide, subtriangular in dorsal view, with oblique dorsal face diverging from rostrum, anterolateral margin slightly concave, oblique, anteromedial angle rounded in dorsal view, reaching distal margin of antennular peduncle article 1. Cornea densely pigmented, sitting proximally on eyestalk.

Antennular peduncle reaching midpoint of margin of antennal peduncle article 5; article 1 barely visible in dorsal view; article 3 longer than articles 1 and 2 combined; articles 2 and 3 with longitudinal ventral row of long setae. Antennal peduncle article 5 0.7 length of article 4; scaphocerite comma-shaped in dorsal view.

Maxilliped 3 ischium dilating over most of length, 1.3 times as long as wide, crista dentata consisting of row of about 35 uneven contiguous teeth; merus 0.65 length of ischium measured along outer margin, about 1.5 times as wide as long, with mesiodistal margin convex, with sharp mesially directed tooth; carpus little shorter than merus outer margin; propodus tapering, 1.7 times as long as greatest width; dactylus 0.65 length of propodus, elongate-oval, with dense row of short setae along flexor (lower) margin.

Pereopods 1 (chelipeds) unequal, dissimilar. Major cheliped carpus-palm upper margin 0.8 carapace length. Ischium expanding distally, upper margin unarmed; lower margin with 8 spines increasing in length distally. Merus as long as ischium, 2.9 times as long as wide; upper margin convex; lower margin unarmed. Carpus 2.3 times as long as wide. Propodus upper margin 0.7 length of carpus; palm 1.3 times as long as wide; upper margin convex; lateral surface smooth, convex; mesial surface convex; lower margin with row of setae extending onto fixed finger; fixed finger about as long as palm; cutting edge irregular. Dactylus as long as fixed finger, curved; cutting edge with 1 low step-like tooth.

Minor cheliped carpus-palm upper margin 0.7 carapace length. Ischium lower margin with 7 spines increasing in length distally. Merus as long as ischium; upper margin convex, smooth; lower margin unarmed. Carpus dilating, as long as merus, 3.4 times as long as wide. Palm half as long as carpus, 1.4 times long as wide; upper margin barely convex; lower margin carinate, with row of setae extending onto fixed finger; fixed finger longer than palm, cutting edge smooth. Dactylus longer than palm, curved distally; cutting edge smooth.

Pereopod 3 carpus subtriangular, twice as long as wide; propodus oval, longer than wide, with evenly curved lower margin, marginal setae evenly spaced, without gaps, with 1 short spiniform seta; dactylus 0.7 length of propodus upper margin. Pereopod 4 propodus as long as carpus, with dense grooming setae distally on lower margin, scattered stiff setae on outer surface, with short spiniform setae at base of dactylus; dactylus half as long as propodus. Pereopod 5 slender, chelate.

Uropod endopod and exopod overreaching posterior margin of telson. Endopod suboval, 1.4 times as long as wide; anterior margin almost straight; anterodistal margin setose, with 4 subdistal spiniform setae; posterior margin with marginal setae; dorsal face with curved row of 10 spiniform setae close to anterior margin, 2 more near posterodistal margin. Exopod ovate, truncate distally, 1.7 times as long as wide; anterior margin convex; posterior margin with 7 falcate setae indistinguishably merged with densely setose distal margin; dorsal plate scarcely indistinguishable from distal margin, comprising short and medium stiff setae merging anteriorly with similar setae on distal margin; dorsal face with 2 short spiniform setae near anterior margin.

Telson 1.1 times as wide as long, widest at strong lateral lobes at one third length, narrowing posteriorly without angle to convex posterior margin; posterolateral margin with 2 spiniform setae; posterior margin setose, with medial spine; lateral lobe with short seta; transverse dorsal ridge with 1 pair of spiniform setae and long setae.

Etymology. From Ningaloo, name of the barrier reef near the type locality (noun in apposition).

Distribution. Northwest Australian Shelf (Western Australia, off Ningaloo; known only from the type locality); 106 m.

Remarks. The single female of P. ningaloo differs significantly from the two other species found on the Australian North West Shelf. Notably, the carpus of the major cheliped is more than twice as long as wide (about as wide as long in P. mandu and P. propinqua ), the uropodal endopod has 12 facial spiniform setae in an irregular row close to the anterior and distoposterior margin (3 or 4 in a group in the other two species), and the uropodal exopod is ovate, 1.7 times as long as wide (more rectangular and narrower in the other two species). The dorsal armature of the uropodal endopod (several spiniform setae in a longitudinal row) of Praedatrypaea ningaloo resembles that of P. praedatrix , but the shorter antenna and the major cheliped with its elongate merus and carpus differ.

Figures

Figure 32.Praedatrypaea ningaloo sp. nov. Australia, North West Shelf. NMV J53459, holotype female, 4.4 mm: a, b, anterior carapace, eyestalks, antennular, antennal peduncles (lateral, dorsal views); c, pleomere 6, telson, left uropod; d, maxilliped 3 (inner view); e, maxilliped 3 ischium, merus (outer view); f, major cheliped (left, lateral view); g, minor cheliped (right, lateral view); h–j, pereopods 3–5. Scale bar = 1 mm.