Michelaxiopsis australiensis (De Man, 1925) 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 : 261-263

Michelaxiopsis australiensis (De Man, 1925) comb. nov.

Figure 26

Axiopsis (Axiopsis) australiensis De Man, 1925a: 127–132 , fig.

4.— De Man, 1925b: 69.— Poore and Griffin, 1979: 226–228, fig. 2. Axiopsis australiensis .— Poore, 2004: 174, figs. 45a, b, 46a. Axius australiensis .— Sakai and de Saint Laurent, 1989: 26,

29.— Sakai, 1992: 165, fig. 7.— Davie, 2002: 451.— Sakai, 1994: 200.

Material examined. NSW, Long Reef, W end of reef (33°44’S, 151°19’E), I. Bennett, Apr 1964, AM P24699 (2 ovigerous females, cl. 20.0, 24.7 mm). Port Jackson , Watsons Bay (33°50.8’S, 151°16.8’E), McIntosh and Whitelegge, Mar 1908, AM P15036 (1 male, cl. 11.7 mm; 2 females, cl. 13.6, 15.0 mm) .

Vic., Shoreham (38°26’S, 145°03’E), AM P1757 (2 juvenile males, cl. 7.2, 8.5 mm) .

Diagnosis. Carapace smooth, with scattered long setae. Rostrum 0.25 times length of front-to-cervical groove, broadly acute, rugose dorsobasally, with 5 lateral spines anterior to supraocular spine, continuous with definite lateral gastric carinae. Supraocular spines barely differentiated from others in row. Lateral gastric carina with 3 or 4 obscure low beads fading posteriorly. Submedian gastric carina duplicated, outer row of 12–15 tubercles curving inwards at anterior end, beading fading posteriorly, inner row of 3–5 tubercles anteriorly, 3–4 posteriorly and clear hiatus between. Median gastric carina with 18–22 tubercles, scarcely taller anteriorly, fading posteriorly.

Antennule article 1with sharp stylocerite. Antennal article 2 distal spine slender, directed anteriorly, reaching distally to quarter of antennal article 4; scaphocerite reaching two-thirds length of article 4, simple; article 3 with short mesiodistal spine on lower margin.

Major pereopod 1 ischium lower margin with 1 spine; merus upper margin convex, unarmed, lower margin with 5 spines, last longest, lateral face smooth, mesial face smooth; carpus upper margin unarmed, lower margin unarmed; propodus upper margin tuberculate, lower margin smooth, lateral face with squamous tubercles concentrated on distal two-thirds along lower margin, few along upper margin, mesial face with squamous tubercles concentrated on distal two-thirds along lower margin, few along upper margin; fixed finger 0.8 length of upper palm, cutting edge with 1 blunt tooth and 1 triangular tooth; dactylus upper margin smooth, lateral face smooth, mesial face smooth, cutting edge with blunt tooth at midpoint and notch proximally, with subapical robust setae prominent.

Minor pereopod 1 of similar length and ornamentation as major cheliped but narrower.

Telson 1.2 times as long as wide, lateral margin unarmed (rarely 1 spine), distal margin convex, with posteromedian spine, posterolateral angle with inconspicuous robust setae; dorsal face with 2 spines in each oblique row. Uropodal endopod 1.2 times as long as wide, with or without lateral spine and 1 distolateral spine, longitudinal ridge with 4–5 spines. Uropodal exopod 1.3 times as long as wide, with 5–6 lateral spines, 2 longitudinal ribs with 3–4 on outer rib, posterolateral angle with 1 fixed spine and 1 robust seta; transverse suture with 6–10 spines.

Distribution. NSW, Vic., intertidal-subtidal. Remarks. Michelaxiopsis australiensis is differentiated from M. nauo by the absence of short stiff setae on the carapace and abdomen. The submedian gastric carina is duplicated, the outer row of tubercles continous and the inner one of three anterior and three or four posterior tubercles separated by a distinct hiatus. The median gastric carina is composed largely of beadlike tubercles,the anteriormost ones only slightly more elevated than posterior ones. The lateral margin of the telson is usually smooth, and only rarely with a small tooth. The absence of the male pleopod 1 and gastric ornamentation exclude this species from Axius to which it has been assigned. Poore and Griffin (1979) listed numerous specimens from central NSW, a few of which where re-examined for this study.

The two small specimens from Victoria are in poor condition. They differ from the others in that the gastric carinae are almost smooth, with only vestiges of the beads or tubercles of larger specimens. The hiatus in the inner submedian row is quite evident.

Figures

Figure 26. Michelaxiopsis australiensis (De Man, 1925). a, b, lateral and dorsal view of anterior carapace, peduncles of antennule and antenna. c, telson and left uropod. d, cheliped (left). All figures from female (AM P24699).