Pilbaraxius kariyarra, Poore & Collins, 2009

Poore, Gary C. B. & Collins, David J., 2009, Australian Axiidae (Crustacea: Decapoda: Axiidea), Memoirs of Museum Victoria 66 (2), pp. 221-287 : 269-272

Pilbaraxius kariyarra sp. nov.

Calaxiopsis sp. — Robles et al., 2009: 314, 316 (molecular phylogeny, GenBank numbers).

Figures 32 , 33 , 45

Material examined. Holotype. WA, off Port Hedland , 18°34.19'S, 117°27.86'E – 18°34.06'S, 117°28.63'E (stn SS05-2007 052), 405– 401 m, 14 Jun 2007, NMV J55576 (male, cl. 6.8, tl. 15.7 mm).

Description of male holotype. Carapace covered in small tubercles. Rostrum 0.4 times length of front-to-cervical groove, acute, elongate, with 1 long lateral spine anterior to supraocular spine, continuous with definite lateral gastric carinae. Supraocular spines prominent. Lateral gastric carina with 1 spine. Submedian gastric carina with 1 spine. Median gastric carina present as a ridge extending anteriorly onto rostrum, with 1 tubercle located midway between rostrum and cervical groove. Postcervical carina on carapace absent. Sternite 7 (pereopod 4) deeply divided in midline over posterior two-thirds and with oblique lateral ridge ending in sharp spine. Sternite 8 (pereopod 5) with setose semicircular flap on anterior face at base of leg. Abdominal pleuron 1, 2.6 times as deep as middorsal length, with small ventral spine; pleuron 2 asymmetrical, lateral length 1.3 times dorsal length, concave ventrally, with 2 distinct ventral spines; pleura 3 and 4 tapering to a ventral spine, with another spine located anteroventrally; pleuron 5 tapering to a ventral spine, with another 2 spines located anteroventrally; pleuron 6 with 1 ventral spine.

Eyestalk 0.25 length of rostrum; cornea weakly pigmented. Antennular peduncle reaching to end of article 4 of antenna. Antennal article 1 with 2 small spines on distal margin; article 2 distal spine straight, approximately half length of article 2; scaphocerite simple, straight, reaching distally almost to end of article 4; article 3 with 1 spine on lower margin; article 4 about as long as article 2 (excluding distal spine); article 5 about half as long as article 4. Maxilliped 3 basis with 1 spine; crista dentata with 15 teeth; merus with 2 spines on lower margin (1 large, 1 small); carpus unarmed.

Pereopods 1 differentiated, propodus of major cheliped longer and more swollen than minor. Major pereopod 1 (right) coxa lower margin with 1 spine; basis lower margin unarmed; ischium lower margin with 1 spine; merus upper margin convex, with 1 hooked spine, lower margin with 1 spine and obsolete tubercle laterally, lateral face with broad tubercle distally, mesial face smooth; carpus upper margin tuberculate, lower margin unarmed, lateral face tuberculate, mesial face smooth; propodus upper margin with 1 distal spine, lower margin with low lateral carina, lateral face tuberculate, mesial face smooth; fixed finger 1.2 times length of upper palm, cutting edge with 4 large irregular rounded teeth; dactylus upper margin smooth, lateral face smooth, mesial face smooth, cutting edge with narrow proximal notch.

Minor pereopod 1 coxa, ischium, merus and carpus as in larger cheliped; propodus similar except mesial face with spine near gape; fixed finger about as long as upper palm, cutting edge with 2 large triangular teeth and smaller intermediate denticles; dactylus cutting edge excavate proximally.

Pereopod 2 unarmed; carpus slightly shorter than chela; propodus upper margin as long as dactylus. Pereopod 3 unarmed; propodus 2.2 times as long as dactylus, with 6 marginal robust setae (some duplicated). Pereopod 4 unarmed; propodus 2.2 times as long as dactylus, with 7 marginal robust setae (some duplicated). Pereopod 5 propodus 3.9 times as long as dactylus, subchelate, with short fixed finger bearing 5 distinct robust setae; dactylus slightly flattened.

Pleurobranchs present above pereopods 2–4; arthrobranchs on maxilliped 2 (rudimentary) to pereopod 4; epipods with well developed podobranchs (with up to 10 gill filaments) on maxilliped 2 to pereopod 3

Pleopod 1 absent. Pleopod 2 appendix masculina absent; appendix interna slender, about quarter length of endopod.

Telson 1.3 times as long as broad, lateral margin with 4 spines, distal margin convex without posteromedian spine, posterolateral angle with 1 robust seta; dorsal face without spines on each oblique row. Uropodal endopod 1.9 times as long as wide, without lateral spines, longitudinal ridge unarmed. Uropodal exopod 1.9 times as long as wide, without lateral spines, longitudinal ribs unarmed, posterolateral angle with 1 robust seta; transverse suture unarmed.

Etymology. Kariyarra is the name of the Australian Aboriginal people inhabiting the coast close to the type locality (noun in apposition).

Distribution. WA, off Port Hedland, 18°S, 118°E, c. 400 m depth (known only from type locality).

Remarks. See the discussion for the genus Pilbaraxius . Unfortunately, the species was placed in a molecular analysis as Calaxiopsis sp. by Robles et al. (2009).

Figures

Figure 32. Pilbaraxius kariyarra sp. nov. a, lateral view. b, dorsal view of carapace, peduncles of antennule and antenna. c, telson and left uropod. d, epistome, left antennule and antenna (ventral). e, major pereopod 1 (right, lateral). f, same (propodus–dactylus, mesial, setae not shown). g, minor pereopod 1 (left, lateral). h, same (propodus–dactylus, mesial, setae not shown). All figures from holotype.

Figure 33. Pilbaraxius kariyarra sp. nov. a, thoracic sternites 7 and 8. b, maxilliped 3. c–f, pereopods 2–5 (c, f right; d, e left). g, pereopod 5 distal propodus and dactylus. h, female pleopod 2. All figures from holotype.

Figure 45. Pilbaraxius kariyarra sp. nov. Photomicrographs of (left to right) maxilla 1, maxilla 2 (posterior epipod seta truncated), maxilliped 1, maxilliped 2.