Calaxius acutirostris Sakai and de Saint Laurent, 1989

Poore, Gary C. B. & Collins, David J., 2009, Australian Axiidae (Crustacea: Decapoda: Axiidea), Memoirs of Museum Victoria 66 (2), pp. 221-287 : 250-253

Calaxius acutirostris Sakai and de Saint Laurent, 1989

Figures 18–20 , 43

Calaxius acutirostris Sakai and de Saint Laurent, 1989: 86–92 , fig. 25 (probably not figs. 23, 24).—Sakai, 192–193, fig. 10.

Material examined. WA, off Zuytdorp, 27°08.01'S, 112°45.04'E – 27°08.48'S, 112°45.43'E (stn SS10-2005 105), 414– 405 m, 05 Dec 2005, NMV J53450 (female, cl. 20 mm, tl. 48 mm). WA, north-west slope, 16°45.3S, 119°46.4'E, 502–504 m, NTM Cr004234 (male, cl. 22.2, tl. 56.0). Qld, off Mackay, 22°55.1’S, 153°00.5’E, 338– 325 m, NTM Cr007158 (male, cl. 26.5, tl. 65.0) .

Description of female NMV J53450. Carapace smooth (with scattered setae). Rostrum 0.5 times length of front-to-cervical groove, acute, with 2 lateral spines anterior to supraocular spine, continuous with definite lateral gastric carinae. Supraocular spines prominent. Lateral gastric carina with 1 prominent spine posterior to supraocular spine. Submedian gastric carina with 2 spines. Median gastric carina present as a ridge with 3 small spines. Faint postcervical carina present, becoming stronger posteriorly. Sternite 7 (pereopod 4) deeply divided in midline over posterior two-thirds and with sharp oblique lateral ridge. Sternite 8 (pereopod 5) with setose semicircular flap on anterior face at base of leg. Abdominal pleuron 1 2.5 times as deep as middorsal length, ventrally acute; pleura 2–5 broad, lateral length 1.3 times dorsal length, tapering posteroventrally to a point, pleura 4 and 5 with small anteroventral tooth; pleuron 6 rounded.

Eyestalk 0.3 length of rostrum; cornea pigmented.

Antennular peduncle reaching to end of antennal article 4. Antennal article 1 with 2 spines on lower distal margin; article 2 distal spine slender, reaching distally to middle of antennal article 4; scaphocerite slender, straight, reaching distally 0.8 length of article 4; article 3 with 1 spine on mesial lower margin; article 4 about 1.3 length of article 2 (excluding distal spine), article 5 about two-thirds length of article 4. Maxilliped 3 basis with 1 spine; ischium with 2 spines on lower margin; crista dentata with 18 teeth; merus with 3 spines on lower margin; carpus unarmed.

Pereopods 1 scarcely differentiated, of similar length, major slightly more swollen than minor, merus of major slightly broader. Major pereopod 1 (right) coxa lower margin with 1 spine; basis lower margin with 1 spine; ischium lower margin with 1 spine; merus upper margin convex, with 2 spines, lower margin with 3 spines, lateral face with 1 distal spine, mesial face smooth; carpus upper margin with 3 spines, lower margin with 2 spines laterally, lateral face smooth, mesial face smooth; propodus upper margin with 4 spines (2 in midline, 1 on each side), lower margin with 8 spines in lateral row, lateral face with row of 4 spines, mesial face with 1 spine and few tubercles near lower margin; fixed finger 1.5 times upper palm, cutting edge with 5 sharp spine-like teeth; dactylus unarmed, cutting edge denticulate; distal articles bearing clusters of stiff setae.

Minor pereopod 1 coxa, ischium, merus and carpus as in larger cheliped; propodus as in larger cheliped except mesial face with 2 spines and few tubercles near lower margin; fixed finger 1.8 times length of upper palm, cutting edge with uneven blunt teeth; dactylus unarmed, cutting edge denticulate; distal articles bearing clusters of stiff setae.

Pereopod 2 ischium lower margin unarmed; merus lower margin with 3 spines; carpus slightly shorter than chela; propodus upper margin 0.8 length of dactylus. Pereopod 3 merus lower margin with 2 spines; propodus 2.7 times as long as dactylus, with 4 marginal robust setal rows. Pereopod 4 merus lower margin with 1 spine; propodus 2.8 times as long as dactylus, with 3 marginal robust setal rows. Pereopod 5 propodus 5 times as long as dactylus, subchelate, with short fixed finger; dactylus twisted.

Pleopod 1 article 2, 3 times article 1. Pleopods 2–5 appendix interna 0.3 length of endopod.

Telson 1.3 times as long as broad, lateral margin with 1 robust seta on proximal lobe, distal margin convex without posteromedian spine, posterolateral angle with 2 robust setae; dorsal face with 2 small spines in each oblique row. Uropodal endopod 1.6 times as long as wide, with 1 distolateral spine, longitudinal ridge with 2 spines (including marginal). Uropodal exopod 1.7 times as long as wide, with 2 obsolete lateral spines, 2 longitudinal ribs unarmed, posterolateral angle with minute fixed spine (robust seta probably lost); transverse suture with 6–10 uneven spines.

Description of male NTM Cr007158. Essentially as female except: rostrum with 3 and 4 lateral spines anterior to supraocular; major cheliped more swollen, propodus mesial face more obviously tuberculate; pleopod 1 absent; pleopod 2 with appendices interna and masculina of similar lengths, each about third length of endopod; telson lateral margin with fixed spine (in place of robust seta) on proximal lobe and robust seta at midpoint; uropodal exopod posterolateral angle with minute fixed spine and robust seta.

Distribution. Madagascar (type locality); Australia, central and northern WA, central Qld, to 27°S, 325–505 m depth.

Remarks. De Saint Laurent (pers. comm., 1990) informed GCBP that, in her view, only figure 25 of C. acutirostris in the original description ( Sakai and de Saint Laurent, 1989) refers to this species whose holotype is from Madagascar; the other figures and part of the description refer to another species from the Philippines. This would appear to differ only in the degree of spination of the chelipeds. Sakai (1994:192, fig. 10) recorded Calaxiusacutirostris from off Queensland and Western Australia, and illustrated and described maxilla 2 and maxillipeds 1–3. We examined his material and found it, like our own, more resembled figure 25 of the type specimen than figure 24 of the Philippines specimen. We figure dorsal views of all Australian specimens to illustrate the elongation of the rostrum with increased size (fig. 20).

The original diagnosis and description were extensive and covered all limbs ( Sakai and de Saint Laurent, 1989) but apart from pereopod 1 no limbs were illustrated. Because of the confusion about which species was referred to, we provide figures and another description based on the Australian material. We note differences in the number of rostral spines (between individuals and between left and right sides)—two to four spines possible, in degree of spination and tuberculation of chelipeds, and in armature of the telson.

Calaxius acutirostris , is similar to C. euophthalma ( De Man, 1905) , C. manningi Kensley et al., 2000 and C. tungi Zhong, 2000 in the possession of two well defined spines on each lateral and sublateral gastric carina. All possess two to four asymmetrical spines on each lateral margin of the rostrum. Calaxius acutirostris and C. manningi also have a similar spination pattern on the chelipeds while C. tungi has fewer and weaker spines. Calaxius euophthalma lacks prominent cheliped spines. Also belonging to this group of Indo-West Pacific species with two or three asymmetrical rostral spines are C. mimasensis ( Sakai, 1967) and C. sibogae ( De Man, 1925b) but these species have less spinose chelipeds than C. acutirostris .

Figures

Figure 18. Calaxius acutirostris Sakai and de Saint Laurent, 1989. a, lateral view. b, dorsal view of carapace, peduncles of antennule and antenna. c, telson and left uropod. d, sternites 7 and 8. e, right sternites 7 and 8 (lateral). f, epistome, left antennule and antenna (ventral). g, maxilliped 3. h, major pereopod 1 (right, lateral). i, same (propodus–dactylus, without setae, mesial). All figures from NMV J53540.

Figure 19. Calaxius acutirostris Sakai and de Saint Laurent, 1989. a, minor pereopod 1 (left, lateral). b, same (carpus–dactylus, without setae, mesial). c–f, pereopods 2–5 (right). g, female pleopod 1. h, male pleopod 2. Figs a–g from NMV J53540, fig. h from NTM Cr007158.

Figure 20. Calaxius acutirostris Sakai and de Saint Laurent, 1989. Detail of rostum (and left antennae) of three specimens. a, female, cl. 20 mm, NMV J53540. b, male, cl. 22.2 mm, NTM Cr004234. c, male, cl. 26.5 mm, NTM Cr007158.

Figure 43. Calaxius acutirostris Sakai and de Saint Laurent, 1989. Photomicrographs of (left to right) maxilla 1, maxilla 2 (posterior epipod seta truncated), maxilliped 1, maxilliped 2.