Axiopsis tsushimaensis Sakai, 1992

Poore, Gary C. B. & Collins, David J., 2009, Australian Axiidae (Crustacea: Decapoda: Axiidea), Memoirs of Museum Victoria 66 (2), pp. 221-287 : 242

Axiopsis tsushimaensis Sakai, 1992

Figures 13 , 40

Axiopsis tsushimaensis Sakai, 1992:173–175 , figs. 14, 15.— Sakai,

1994: 198.— Komai et al., 2002: 19–30, figs. 1–3.

Material examined. WA, off Bald Island , 35°11.26'S, 118°38.42'E – 35°11.15'S, 118°39.00'E (stn SS10-2005 035), 157– 157 m, 24 Nov 2005, NMV J55437 (male, cl. 6.8 mm, tl. 19 mm). WA, Jurien Bay, 29°48.25'S, 114°25.52'E – 29°48.33'S, 114°25.55'E (stn SS10-2005 083), 113–114 m, 02 Dec 2005, NMV J55444 (juvenile, cl. 3.0 mm) .

Diagnosis. Carapace generally smooth except in gastric region. Rostrum 0.4 times length of front-to-cervical groove, broadly acute, with 4–5 lateral spines anterior to supraocular spine, continuous with definite lateral gastric carinae. Supraocular spines not differentiated from others in row. Lateral gastric carina with 9–10 low spines. Submedian gastric carina duplicated, each row of 6–8 low spines. Median gastric carina with 9–10 low spines.

Antennal article 2 distal spine slender, directed slightly upwards, reaching distally to quarter of antennal article 4; scaphocerite reaching distally to end of article 4, simple; article 3 with sharp mesiodistal spine on lower margin.

Pereopods 1 significantly differentiated. Major pereopod 1 ischium lower margin with 5 denticles and 1 spine; merus upper margin convex, with 1 spine, lower margin with 7 spines, last longest, and sublateral proximal row of denticles, lateral face smooth, mesial face smooth; carpus upper margin unarmed, lower margin unarmed; propodus upper margin with ridge of 11 low blunt teeth, lower margin with ridge of 11 low blunt teeth, lateral face with low tubercles concentrated near margins on distal two-thirds (absent proximally and from fixed finger), mesial face with low tubercles concentrated near margins on distal two-thirds (absent proximally and from fixed finger); fixed finger 0.5 length of upper palm, cutting edge with irregular rounded teeth, largest at midpoint; dactylus upper margin tuberculate, lateral face tuberculate proximally, mesial face tuberculate proximally, cutting edge with major tooth at midpoint and notch proximally; both fingers bearing setae.

Minor pereopod 1 coxa, ischium, merus and carpus as in major cheliped but narrower; propodus upper margin with sharp ridge, lower margin ridge of 11 low blunt teeth, lateral face mostly smooth, mesial face with few tubercles; fixed finger as long as upper palm, cutting edge with c. 25 short sharp teeth; dactylus upper margin unarmed, lateral face smooth, mesial face with few denticles, cutting edge obscurely denticulate.

Telson 1.1 times as long as wide, lateral margin with 3 spines, distal margin convex, with posteromedian spine, posterolateral angle with 4 robust setae well separated; dorsal face with 2 spines in each oblique row. Uropodal endopod 1.5 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 6 lateral spines, 2 longitudinal ribs unarmed, posterolateral angle with 1 fixed spine and 1 robust seta; transverse suture with 10 spines.

Male. Pleopod 2 appendix interna 0.3 length of endopod; appendix interna 0.7 length of appendix interna.

Distribution. Tsushima Strait ( Korea Strait), southern Japan; Sulu Sea, Philippines; WA, south-western coast; 34°N – 35°S, 114°– 130°E, 102–157 m depth.

Remarks. Sakai (1992) based his description of Axiopsis tsushimaensis on a juvenile female (tl. 18 mm) without a larger cheliped. Komai et al.’s (2002) detailed description and illustrations were likewise based on a small female. We illustrate for the first time an adult male and show in particular the strongly dimorphic chelipeds and pleopod 2. We could not detect differences in the carapace armature, abdomen, tail fan or antennae between our material and the type. The species is similar to A. consobrina De Man, 1905 in having a spine on the upper margin of the merus of the chelipeds and the proximal lateral surface of the larger cheliped smooth. Axiopsis tsushimaensis differs principally in having a double (rather than single) gastric submedian gastric carina and scaphocerite without a basal mesial spine (obvious to De Man, 1925b). While A. consobrina was described from slightly larger specimens (tl. 21, 29.5 mm), these differences would not appear to be size related as evidenced by our examination of a size range of the similar A. serratifrons ( Milne-Edwards, 1873) in NTM collections (Cr0009886, Cr010271).

Figures

Figure 13. Axiopsis tsushimaensis Sakai, 1992. a, lateral view. b, dorsal view of carapace, peduncles of antennule and antenna. c, right antenna peduncle (lateral). d, telson and left uropod. e, major pereopod 1 (left). f, minor pereopod 1 (right). g, h, i, pereopods 2, 4, 5 (left except g, with detail of perepod 4). j, male pleopod 2, with detail of appendices interna and masculina. All figures from NMV J55437.

Figure 40. Axiopsis tsushimaensis Sakai, 1992. Photomicrographs of (left to right) maxilla 1, maxilla 2 (posterior epipod seta truncated), maxilliped 1, maxilliped 2.