Bouvieraxius keiensis Sakai, 1992

Poore, Gary C. B. & Collins, David J., 2009, Australian Axiidae (Crustacea: Decapoda: Axiidea), Memoirs of Museum Victoria 66 (2), pp. 221-287 : 245-247

Bouvieraxius keiensis Sakai, 1992

Bouvieraxius keiensis Sakai, 1992: 166–168 , figs. 8, 9.

Bouvieraxius rudis .— Sakai, 1994: 177 (not Axius rudis Rathbun, 1906 ).

Bouvieraxius michelae Poore, 2008: 162–164 , fig. 1. (syn. nov.)

Figures 15 , 16 , 41

Material examined. WA, off Kalbarri, 27°48.48'S, 113°18.40'E – 27°49.06'S, 113°18.43'E (stn SS10-2005 102), 96–98 m, 05 Dec 2005, NMV J55441 (male, cl. 9.8 mm; female, cl. 10.0 mm). Off Zuytdorp, 27°03.06'S, 113°13.19'E – 27°02.56'S, 113°06.00'E (stn SS10-2005 104), 97 m, 05 Dec 2005, NMV J53445 (damaged carapace with chelipeds, abdomen missing). Off Shark Bay , 25°54.27'S, 112°49.23'E – 25°54.26'S, 112°49.44'E (stn SS10-2005 035), 100 m, 06 Dec 2005, NMV J53444 (2 ovigerous females, cl. 10.0 mm; male with bopyrid parasite, cl. 8.3 mm). S of Shark Bay, (SS10-2005 stn not recorded), NMV J55471 (male, cl. 10.8 mm). Off Barrow I., 21°02.15'S, 114°53.28'E – 21°01.99'S, 114°53.14'E (stn SS05-2007 008), 90–100 m, 10 Jun 2007, NMV J55709 (damaged male, cl. 6.0 mm). North West Shelf, 19°50.0'S 115°34.0'E, 80 m, NTM Cr 000886 (ovigerous female, cl. 8.0 mm, tl. 23.5 mm, determined as Bouvieraxius rudis by Sakai, 1994) .

Diagnosis. Carapace smooth. Rostrum 0.3 times length of front-to-cervical groove, narrowly triangular, with 3 (sometimes fourth obsolete) lateral spines anterior to supraocular spine, continuous with definite lateral gastric carinae. Supraocular spines similar in size to other rostrum spines.Lateral gastric carina unarmed behind supraocular spine. Submedian gastric carina with 3 or 4 spines. Median gastric carina unarmed. Abdominal pleura 3–6 each with small anteroventral tooth in male only (female pleura rounded).

Eyestalk 0.5 length of rostrum; cornea pigmented. Antennular peduncle reaching to proximal part of antennal article 5. Antennal article 1 with 1 spine and 2 spinules on lower distal margin; article 2 distal spine slender, directed distally, reaching distally to one third of antennal article 4; scaphocerite slender, straight, reaching distally to 0.7 length of article 4; article 3 with 1 or 2 spines on mesial lower margin; article 4 about half length of article 2 (excluding distal spine), without spine, article 5 about two-thirds length of article 4. Maxilliped 3 basis with 1 spine; ischium with 3 spines on lower margin; crista dentata with 18 teeth; merus with 4 spines on lower margin; carpus with 1 spine on lower margin.

Pereopods 1 unequal, of similar length, propodus of major cheliped more swollen than in minor. Major pereopod 1 coxa lower margin with 1 spine; basis lower margin with 1 spine; ischium lower margin with 2–4 spines; merus upper margin convex, with 2 or 3 spines, lower margin with 5–9 spines, lateral face smooth, mesial face smooth; carpus smooth and unarmed; propodus upper margin with 1 row of c. 27 blunt truncate teeth, lower margin with obsolete scale-like teeth, lateral face tuberculate, especially distally near upper and lower margins, mesial face tuberculate, especially near upper margin; fixed finger 1.4–1.6 length of upper palm, cutting edge weakly toothed; dactylus upper margin smooth—weakly tuberculate, lateral face smooth, mesial face smooth, cutting edge irregularlly toothed.

Minor pereopod 1 spination and tuberculation as in larger cheliped (numbers of spines on merus show same range of values but pair often asymmetrical); propodus less swollen, slightly narrower, fixed finger as long as upper palm.

Male pleopod 1 article 2 with distal lobe bearing hooks proximally, mesial lobe reaching halfway along article 3. Male pleopod 2 appendix masculina about as long as endopod, extending beyond endopod by half its length. Pleopods 2–5 appendix interna one third length of endopod.

Telson 1.3 times as long as broad, lateral margin with 3 spines, distal margin convex with posteromedian spine, posterolateral angle with 1 robust seta; dorsal face with 2 spines in each oblique row. Uropodal endopod 1.3 times as long as wide, with 2 lateral spines, longitudinal ridge with 5 spines (including marginal). Uropodal exopod 1.4 times as long as wide, with 1 or 2 lateral spines, 2 longitudinal ribs (ribs with 7 scattered denticles), posterolateral angle with 1 fixed spine and 1 robust seta; transverse suture with 16–20 spinules.

Distribution. Indonesia (Kei Island), 245 m; Timor Sea, 18 m; Mauritius, 73 m; WA, North West Shelf to Shark Bay, 20°– 27°S, 113°– 115°E, 80–100 m depth.

Remarks. Bouvieraxius keiensis was described from material from Kei Island, Indonesia (type locality) and Mauritius. The new material from the region of Shark Bay, central WA, totals nine specimens that vary in the number of lateral spines on the rostrum anterior to the supraocular spine (two or three, the last often obsolete), teeth on the submedian gastric carina (usually four, three in two individuals, five on one side in one individual), spines on the merus of the cheliped (two or three on the upper margin, 6–9 on the lower margin, usually asymmetrical), and extent of tuberculation on the propodus of the cheliped (from one third to two thirds of the lateral surface). Sakai’s (1994) illustrations (taken from three individuals) show two lateral spines on the rostrum, four teeth on the submedian gastric carina, four upper and five lower spines on the merus of the cheliped, and extensive tuberculation on the propodus of the cheliped. While the spination of the cheliped meri of the holotype falls outside the range of the Australian material we can see no other differences; otherwise, the tail fan and male pleopods seem identical. We illustrate an ovigerous female of a size similar to Sakai’s specimens; both show the inequality in the female chelipeds that is mirrored in males.

Bouvieraxius michelae was described on the basis of a small male (cl. 4.2 mm) from the Timor Sea. The holotype lacks chelipeds. Dorsal spination is essentially the same as in the figures of B. keiensis ; its more elongate telson could be attributed to its small size. The male pleopod 1 of B. michelae lacks a mesial lobe overlapping an apical third article, apparently less developed than that figured for the new material (cf. fig. 15h with Poore, 2008: fig. 1). The pleopod 2 of the small male of B. michelae has a shorter and less setose appendix masculina and rami than those of the larger specimen figured here but male pleopods 1 and 2 of both specimens are consistent with those figured for B. keiensis ( Sakai, 1992: fig. 9). We conclude that B. michelae is a junior synonym of B. keiensis .

Sakai (1994) identified a small female from the North West Shelf, WA, as the Hawaiian species, Bouvieraxius rudis ( Rathbun,1906) .Weexaminedhisspecimen(NTMCr000886) and noted three teeth on the submedian gastric carina as reported for B. rudis (the types of B. keiensis have four). Two males (J55471, J55709) from our new collections also have only three pairs of submedian teeth but are otherwise identical. Sakai noted that the rostrum has three rostral spines (including the supraocular) while B. rudis has two (Rathbun said “three or four” and Sakai and de Saint Laurent illustrated two or three). The cheliped merus of the NTM specimen has 2+6 spines, different from the types of both species but within the range of our new Australian material. Sakai (1994) differentiated B. keiensis from B. rudis on the number of teeth on the submedian gastric carina (4 or 5 vs 3) and the number of mesiodistal spinules on article 1 of the antenna (2 vs 4 or 5 in B. rudis from New Caledonia). The identity of the New Caledonian specimens ( Sakai and de Saint Laurent, 1989) is uncertain (M. de Saint Laurent, pers. comm., 1990). The mesiodistal angle of article 1 of the antenna in our material varied from barely angular to two or three spinules.

The synonymy or otherwise of B. rudis and B. keiensis remains uncertain and until this is resolved we prefer to use the name associated with a species from the region.

Figures

Figure 15. Bouvieraxius keiensis Sakai, 1992. 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). f, minor pereopod 1 (left). g, maxilliped 3. h, i, male pleopods 1, 2. j, k, female pleopods 1, 2. l, left pleura of abdominal somites 3–6. Figs a–e, j, k from NMV J55441 female; figs. h, i, l from male, NMV J55441.

Figure 16. Bouvieraxius keiensis Sakai, 1992. a–d, pereopods 2–5 (right except d). All figures from female, NMV J55441.

Figure 41. Bouvieraxius keiensis Sakai, 1992. Photomicrographs of (left to right) maxilla 1, maxilla 2 (posterior epipod seta truncated), maxilliped 1, maxilliped 2.