Austrotheres pregenzeri, Ahyong, 2018

Ahyong, Shane T., 2018, Revision of Ostracotheres H. Milne Edwards, 1853 (Crustacea: Brachyura: Pinnotheridae), Raffles Bulletin of Zoology 66, pp. 538-571: 547-550

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Austrotheres pregenzeri

new species

Austrotheres pregenzeri   new species

( Figs. 5 View Fig , 6 View Fig )

Ostracotheres holothuriensis   . — Pregenzer, 1988: 21–28, figs. 10–16, 12a, 17–19. — Poore, 2004: 484, 486, fig. 154c, g, pl. 26H. — Ng et al., 2008: 250. (Not O. holothuriensis   [ Baker, 1907]).

Pinnotheres holothuriensis   . — Davie, 2002: 433. (Not P. holothuriensis Baker, 1907   ).

Type material (all New South Wales, Australia). Holotype: AM P72226 View Materials , female (cl 10.5 mm, cw 10.2 mm), S of Point Stephens lighthouse, Port Stephens , 32°45′02″S, 152°11′35″E, 14 m, from Herdmania sp.   , NSW1488, coll. S. Keable et al., 31 May 1998 GoogleMaps   . Paratypes: AM P80529 View Materials , 1 ovigerous female (cl 10.4 mm, cw 9.1 mm), SW side Boodelbah Island , E of Port Stephens, 32°42.4998′S, 152°13.5258′E, 10–13 m, from Herdmania sp.   encrusted with hydroids, sloping boulder reef meeting flat sand bottom, NSW2905 (photo 16), coll. S. Keable et al., 10 March 2006 GoogleMaps   ; AM P63040 View Materials , 1 male (cl 4.9 mm, cw 4.6 mm), 1 ovigerous female (cl 8.6 mm, cw 7.7 mm), Kurnell Pier , Botany Bay, 34°00.2′S, 151°12.5′E, 7 m, from pylons/pilings GoogleMaps   , BB KP1 P2-7, NSW Fisheries   / CRIMP Survey , 21 Oct 1998   .

Other material examined (all Australia). QUEENSLAND: MNHN-IU-2008-12984 (B9780), 1 ovigerous female (cl 9.8 mm, cw 9.0 mm), Heron Island, coll. A.J. Bruce, 1968.

NEW SOUTH WALES: QM W18368 View Materials , 1 male (cl 6.1 mm, cw 5.6 mm), ‘ The Needles’ , Julian Rocks, Byron Bay, 28°36′08″S, 153°37′07″E, 12 m, fringing reef, from Herdmania grandis   , coll. J. Kennedy, 2 February 1993 GoogleMaps   ; AM P101806, 1 ovigerous female (cl 8.5 mm, cw 7.7 mm), NW end South Solitary Island , 30°12.116′S, 153°15.978′E, 17.4 m, steep incline with large drab boulders encrusted with fixed growth, from Herdmania sp.   NSW2808, coll GoogleMaps   . R. Springthorpe , 1 February 2005   ; AM P58218 View Materials , 1 juvenile female (cl 3.9 mm, cw 3.7 mm), bulk liquids berth, Botany Bay , 33°58.5′S, 151°12.6′E, 3 m, from pylons/pilings GoogleMaps   , BB KP1 P1-3, NSW Fisheries   / CRIMP Survey , 19 October 1998   ; AM P63041 View Materials , 1 spent female (cl 7.2 mm, cw 6.2 mm), Channel Marker 4, Botany Bay, 33°59.3′S, 151°12.6′E, 3 m, from pylons/pilings GoogleMaps   , BB CH 4 P1-3, NSW Fisheries   / CRIMP Survey , 21 October 1998   ; AM P58219 View Materials , 1 ovigerous female (cl 8.4 mm, cw 7.8 mm), Kurnell Pier , Botany Bay, 34°00.0′S, 151°12.5′E, 7 m, from pylons/pilings GoogleMaps   , BB KP1 P3-7, NSW Fisheries   / CRIMP Survey , 21 October 1998   ; AM P63135 View Materials , 1 juvenile female (cl 4.6 mm, cw 4.2 mm), dorsally beyond eye; antennal articles 1 and 2 fused to epistome. Eyes filling orbit, cornea pigmented   .

Maxilliped 3 ( Fig. 6D View Fig ) margins and surface with short setae; ischiomerus length about 2.3 × width; inner, proximal twothirds weakly concave, distomesial angle obtusely rounded; distal margin produced slightly beyond palp articulation; outer margin strongly convex. Carpus half propodus length. Propodus spatulate, length about twice width, distally widened, apex blunt, rounded. Exopod margins convex.

Port Kembla, 34°28.3′S, 150°57.5′E, outer side of eastern breakwater, 7 m, from pylons/pilings, PK EBO Qual, NSW Fisheries/ CRIMP Survey , 16 May 2000   ; NMV J13221 View Materials , 3 View Materials ovigerous females (cl 6.4 mm, cw 5.7 mm; cl 9.9 mm, cw 8.9 mm; cl 11.5 mm, cw 10.6 mm), Shellharbour , 34°35′S, 150°52′E, coll. J.E. Watson, 1975 GoogleMaps   ; AM P101807, 1 ovigerous female (cl 7.8 mm, cw 7.2 mm), NW of Bass Point, under gravel loader jetty, Shellharbour , 34°35′29.91″S, 150°53′07.53″E, 10 m, scrapings including small Herdmania grandis   and small encrusting orange bryozoan, NSW3908, 2 May 2010 GoogleMaps   ; ZRC 2018.1067 View Materials , 1 male (cl 2.9 mm, cw 2.8 mm), 1 ovigerous female (cl 8.6 mm, cw 7.6 mm), NW of Bass Point, under gravel loader jetty, Shellharbour , 34°35′29.91″S, 150°53′07.53″E, 10.6 m, from Herdmania grandis, NSW   3924, 2 May 2010 GoogleMaps   .

Description. Female: Carapace ( Fig. 6A, B View Fig ) subcircular to longitudinally subovate, slightly longer than wide, lateral margins rounded to slightly flattened, longitudinally vaulted, profile rounded in lateral view; front slightly produced, subtruncate, broadly rounded, medially straight or weakly emarginated; anterolateral margins defined, coarsely irregular; dorsal surface rugose, regions weakly inflated across anterior half of carapace, demarcated by shallow grooves, surfaces rugose, irregularly, coarsely tuberculate, granulate, most pronounced in largest specimens; epigastric region slightly raised, anterior ridge prominent, transverse, anteriorly divided into four by short emarginations; posterior half of surface smooth or with scattered granules.

Epistome ( Fig. 6C View Fig ) with broad triangular interantennular septum; median buccal margin with obtuse median point. Antennular sinus larger than orbit; antennules folded slightly obliquely. Antenna short, free antennal articles not extending Cheliped (pereopod 1) ( Fig. 6A, E View Fig ) outer surface largely glabrous. Dactylus and pollex relatively straight, crossing distally, without gape, with row of short setae. Dactylus as long as dorsal margin of propodus palm, occlusal margin with 2 small teeth; surfaces smooth. Pollex occlusal margin irregular, crenulate, with low blunt tooth at midlength; inner ventral margin setose; inner surface of palm with short scattered setae. Propodus palm dorsal margin length 1.3–1.5 × height; ventral margin distinctly weakly concave at base of pollex. Carpus mesial margin with brush of setae, unarmed; merus unarmed, stout, shorter than propodus.

Walking legs (pereopods 2–5) similar ( Fig. 6F–I View Fig ); relative lengths: pereopod 2≈pereopod 3>pereopod 4>pereopod 5; smooth, sparsely setose; pereopod 2 propodus with row of short flexor marginal setae; pereopod 3–4 propodus with row of long natatory setae near extensor margin, extending onto dorsal surface of carpus, each article with row of natatory setae on flexor margin, with short row of distal flexor marginal setae; pereopod 5 propodus flexor margin and distal meral flexor margin setose. Meri unarmed, length 3.5–3.9 × height (pereopods 2–4), about 3.4 × height (peroepod 5). Propodi unarmed, 3.2–3.8 × height. Dactyli similar, stout, strongly curved, falcate, evenly tapering, apices spiniform, corneous; flexor margin sparsely setose proximally; pereopod 2–4 dactyli 0.6 × propodus length; pereopod 5 dactylus 0.7 × propodus length.

Egg diameter 0.3–0.4 mm (in preservative).

Male: Similar to female but smaller maximum size, carapace tuberculation less pronounced ( Fig. 6K View Fig ). Cheliped palm with shallow, irregular pitting; palm dorsal margin length 1.2–1.3 × height. Abdomen narrow ( Fig. 6N View Fig ), distally tapering, widest at somite 3; somite 6 weakly trapezoid, slightly wider than long, about as along as telson; telson slightly wider than long, apex rounded to subtruncate. G1 with long setae along central one-third of margins, small tuft of short setae on step proximal to gently sinuous, glabrous, finely tapering, lanceolate tip ( Fig. 6O, P View Fig ). G2 short, simple, about one-fourth G1 length; exopod absent ( Fig. 6Q View Fig ).

Hosts. Ascidians, Pyuridae   : confirmed from Herdmania grandis ( Heller, 1878)   but reported from H. momus ( Savigny, 1816) ( Pregenzer, 1988)   . Kott (2002), however, showed that H. grandis   in temperate Australia has been mistaken for the tropical H. momus   . Pregenzer’s (1988) host records of H. momus   are probably based on H. grandis   .

Etymology. Named after Charles Pregenzer, for his contributions to the knowledge of Australian pinnotherids. Charles was the first to report specimens of this new species, albeit under the name A. holothuriensis   .

Remarks. Review of type and other material of A. holothuriensis   shows that the species is restricted to southern Australia between Victoria and Western Australia. Previous records of A. holothuriensis   from New South Wales ( Pregenzer, 1988) are referable to A. pregenzeri   new species, presently known only from eastern Australia between southern Queensland central New South Wales. The two species thus have discrete distributions ( Fig. 5 View Fig ), with that of A. pregenzeri   encompassing the Peronian and Solanderian provinces, and A. holothuriensis   corresponding largely to the Flindersian Province and extending slightly into the Solanderian Province at Shark Bay, Western Australia ( Ahyong, 2017).

Austrotheres pregenzeri   differs from A. holothuriensis   in carapace ornamentation. In contrast to the smooth carapace with weakly indicated epigastric ridges of A. holothuriensis   , the carapace surface of A. pregenzeri   is rugose and epigastric ridges marked ( Fig. 6A, B, K View Fig ). The carapace of male A. pregenzeri   is irregularly rugose and granular, with shallow demarcations between regions, but in females, ornamentation is much more elaborate. Female A. pregenzeri   have pronounced carapace regions on the anterior half, covered in granules or irregular nodules. Surface ornamentation tends to be nodulose and isolated in smaller specimens, becoming increasingly coalesced and also more granular in the largest specimens. Small scattered granules are also present on the posterolateral and posterior margins of the carapace in the largest specimens. Although the rugose carapace ornamentation is most pronounced in the largest specimens, the smallest juvenile female examined (cl 3.9 mm, AM P58218 View Materials ) already has low irregular granules and weakly developed rugosities on the anterolateral surfaces of the carapace; by cl 4.6 mm (AM P63135 View Materials ), the distinctive carapace ornamentation is well developed. Likewise, carapace rugosity is evident in the smallest male examined (cl 2.9 mm, ZRC 2018.1067).

Morphological variation is slight in A. pregenzeri   apart from the allometric changes in carapace ornamentation. Juvenile females have a more prominent front than adults, somewhat resembling that of males, and up to about 4 mm cl, have a narrow, male-form abdomen. Females are ovigerous by at least cl 6.4 mm, with a rounded, expanded abdomen. The smallest male examined (cl 2.9 mm, AM P101808) is sexually mature, with fully developed gonopods.

Austrotheres pregenzeri   is commensal with ascidians, but a number of specimens were collected in the open, amongst algae and other biofouling. Austrotheres pregenzeri   probably frequently spends time outside of the host as is probably also the case for A. holothuriensis   .

Distribution. Known only from eastern Australia, from scattered localities between Heron Island, Queensland, and Shellharbour, New South Wales; 3–17.4 m.


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Austrotheres pregenzeri

Ahyong, Shane T. 2018

Pinnotheres holothuriensis

Davie PJF 2002: 433

Ostracotheres holothuriensis

Ng PKL & Guinot D & Davie PJF 2008: 250
Poore GCB 2004: 484
Pregenzer C 1988: 21