Austrotheres holothuriensis ( Baker, 1907 ), Ahyong, 2018

Ahyong, Shane T., 2018, Revision of Ostracotheres H. Milne Edwards, 1853 (Crustacea: Brachyura: Pinnotheridae), Raffles Bulletin of Zoology 66, pp. 538-571: 550-553

publication ID

http://doi.org/10.5281/zenodo.5359739

publication LSID

lsid:zoobank.org:pub:8F3A63EE-E132-4E18-8C58-C7034BFDA4A0

persistent identifier

http://treatment.plazi.org/id/D33B87B4-FF8C-FFA9-578A-3E4B853D72C3

treatment provided by

Valdenar

scientific name

Austrotheres holothuriensis ( Baker, 1907 )
status

 

Austrotheres holothuriensis ( Baker, 1907)  

( Figs. 5 View Fig , 7 View Fig )

Pinnoteres holothuriensis Baker, 1907: 177   , 178, pl. 23: fig 3 (type locality: Gulf St. Vincent, South Australia).

Pinnoteres obesa   . — Fulton & Grant, 1906: 18 (Not P. obesa Dana, 1852   ).

Pinnotheres obesus   . — Schmitt et al., 1973: 60. — Davie, 2002: 433–434. (Not P. obesa Dana, 1852   ).

Ostracotheres   (?) (‘ Pinnotheres   ’) holothuriensis   . — Tesch, 1918: 287 (list).

Pinnotheres holothuriensis   . — Tesch, 1918: 262. — Hale, 1927a: 173, 174, fig. 175. — Silas & Alagarswarmi, 1967: 1192, 1200. — Schmitt et al., 1973: 6, 14, 49–50. — Davie, 2002: 433.

Ostracotheres holothuriensis   . — Takeda & Konishi, 1989: 1222. — Berggren, 1999: 187. — Ahyong & Brown, 2003: 11–12. — Ng et al., 2008: 250.

Type material. Lectotype: SAM C1389 View Materials , female (cl 8.3 mm, cw. 7.2 mm; dry), Gulf St. Vincent, 12 fathoms [22 m], in holothurians, coll. J.C. Verco.   Paralectotypes: SAM C12652 View Materials , 1 male (cl 6.2 mm, cw 6.5 mm; dry), Gulf St. Vincent, 12 fathoms [22 m], in holothurians, coll. J.C. Verco   ; SAM C1388 View Materials , 1 male (cl 4.3 mm, cw 4.3 mm), 1 juvenile male (cl 3.6 mm, cw 3.5 mm), 1 female (cl 5.3 mm, cw 4.9 mm), 1 juvenile female (cl 3.1 mm, cw 3.6 mm), Gulf St. Vincent, 5 fathoms [9 m], in ascidians, coll. J.C. Verco.  

Other material examined (all Australia). VICTORIA: AM G5724, 1 male (cl 5.5 mm, cw 5.2 mm), Shoreham, Victoria, dredged, coll. F. Grant, 1900   ; NMV J58309 View Materials , 1 female (cl 5.4 mm, cw 5.2 mm), Popes Eye, Port Phillip Bay , 38°17′S, 144°41′E, 6–10 m, from algal sample, coll. J. Watson, 22 March 2008 GoogleMaps   ; NMV J10682 View Materials , 1 View Materials ovigerous female (cl 11.6 mm, cw 11.4 mm), eastern Bass Strait , S of Waratah Bay, 39°10′S, 145°59.8′E, 69 m, polyzoa bottom, HMAS Kimbla, K 7/73-65, 26 November 1973 GoogleMaps   .

TASMANIA: AM P4047, 1 female (cl 13.6 mm, cw 12.6 mm), E of Schouten Island , 73–92 m, coll. C. Harrison   , 1910; NMV J10739 View Materials , 1 male (cl 3.3 mm, cw 3.0 mm), Little Squally Cove, Deal Island, Bass Strait , 39°29′S, 147°21′E, 20 m, 3 May 1974 GoogleMaps   ; NMV J10740 View Materials , 1 juvenile male (cl 2.4 mm, cw 2.2 mm), Little Squally Cove, Deal Island, Bass Strait , 39°29′S, 147°21′E, 20 m, 3 May 1974 GoogleMaps   .

SOUTH AUSTRALIA: NMV J10684 View Materials , 1 female (cl 9.2, cw 8.4 mm), Point Sinclair , 32°06′S, 132°59′E, coll. D.C. Pearsons, 26 June 1973; NMV J10737 View Materials , 2 females (cl 8.1 mm, cw 7.3 mm; cl 7.1 mm, cw 6.6 mm), Point Sinclair, 32°06′S, 132°59′E, coll. D.C. Pearsons, 10 May 1973; SAM C1506 View Materials , 1 male (cl 4.1 mm, cw 4.3 mm), 1 female (cl 10.3 mm, cw 9.4 mm) GoogleMaps   , South Australia.

WESTERN AUSTRALIA: WAM C23501 View Materials , 1 View Materials ovigerous female (cl 11.8 mm, cw 10.4 mm), Port Jackson Cove, Fitzgerald River National Park , 34°31.064′S, 119°15.911′E GoogleMaps   , 9

m, inside Herdmania momus   , large boulders, mostly covered in brown algae, stn F38, coll. M. Berggren, 20 March 1997; WAM C23495 View Materials , 1 ovigerous female (cl 9.7 mm, cw 9.1 mm), 1 spent female (cl 11.6 mm, cw 11.0 mm), Stream Beach, CALM Fitzgerald Reserve, 34°29.69′S, 119°17.01′E, 12 m, inside Herdmania momus   with Notopontonia platycheles   , granite reef, stn F12, coll. M. Berggren, 13 March 1997; WAM C23500 View Materials , 1 male (cl 4.4 mm, cw 4.0 mm), 1 ovigerous female (cl 13.6 mm, cw 13.0 mm), NW side Horatio Island, CALM Fitzgerald Reserve, 34°30.365′S, 119°17.283′E, 18 m, inside Herdmania momus   , granite reef, brown algae, under large boulder covered with sponges & a few tunicates, stn F37, coll. M. Berggren, 20 March 1997; WAM C23499 View Materials , 1 male (cl 6.4 mm, cw 6.0 mm), James Cove, CALM Fitzgerald Reserve, 34°22.394′S, 119°26.835′E, 9 m, inside Herdmania momus   , limestone reef covered in brown algae, stn F32, coll. M. Berggren, 18 March 1997; WAM C23493 View Materials , 1 ovigerous female (cl 11.0 mm, cw 9.9 mm), Peppermint Beach South, CALM Fitzgerald Reserve, 34°24.028′S, 119°28.704′E, 12 m, granite reef, inside Herdmania momus   with Notopontonia platycheles   , stn F12, coll. M. Berggren, 11 March 1997; WAM C23494 View Materials , 1 male (cl 7.8 mm, cw 7.6 mm), 1 ovigerous female (cl 11.0 mm, cw 10.5 mm), 1 juvenile female (cl 3.8 mm, cw 3.6 mm), Peppermint Beach South, CALM Fitzgerald Reserve, 34°24.028′S, 119°28.704′E, 12 m, granite boulders covered in algae, 9–12 m, inside Herdmania momus   together with shrimps, stn F10, coll. M. Berggren, 10 March 1997; WAM C23498 View Materials , 1 ovigerous female (cl 9.0 mm, cw 8.3 mm), Whalebone Point, CALM Fitzgerald Reserve, 34°21.891′S, 119°31.597′E, 12 m, inside Herdmania momus   , granite reef, some boulders, dense brown algae cover, stn F28, coll. M. Berggren, 18 March 1997; WAM C23497 View Materials , 1 male (cl 7.3 mm, cw 7.0 mm), 1 ovigerous female (cl 14.8 mm, cw 13.6 mm), 1 female (cl 10.5 mm, cw 10.3 mm), Doubtful Islands (middle), 34°22.335′S, 119°36.241′E, 18 m, inside Herdmania momus   with Notopontonia platycheles   , rocky reef, dense cover of brown algae on free surfaces, stn F26, coll. M. Berggren, 17 March 1997; WAM C23496 View Materials , 1 male (cl 9.2 mm, cw 8.8 mm), 1 ovigerous female (cl 11.5 mm, cw 10.3 mm), Red Island Point, CALM Fitzgerald Reserve, 34°01.617′S, 119°46.889′E, 12 m, inside Herdmania momus   with Notopontonia platycheles   , granite reef, high ridge on moderate slope, boulders, brown algae cover, stn F23, coll. M. Berggren, 16 March 1997; WAM C17302 View Materials , 1 male (cl 5.5 mm, cw 5.4 mm), between Rottnest Island and Fremantle, triangle dredge, RV Flinders stn 11, coll. M. Clark, 27 June 1975; WAM C23502 View Materials , 1 female (cl 10.0 mm, cw 9.2 mm; with rhizocephalan externa), N of Wedge Rock, outside Hospital Bay, Bernier Island, Shark Bay, 24°47.60′S, 113°10.26′E, 8–9 m, inside Herdmania momus   with shrimp, stn SB214, coll M. Berggren, 17 April 1997.

Description. Female: Carapace ( Fig. 7A, R View Fig ) subcircular to longitudinally subovate, slightly longer than wide in adults, slightly wider than long to slightly longer than wide in juveniles, lateral margins rounded to slightly flattened, longitudinally vaulted, profile rounded to sinuous in lateral view; front slightly produced, subtruncate, broadly rounded, medially straight or weakly emarginated; anterolateral margins defined; dorsal surface smooth, without tubercles, regions not indicated; epigastric ridge blunt.

Epistome ( Fig. 7S 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 dorsally beyond eye; antennal articles 1 and 2 fused to epistome. Eyes filling orbit, cornea pigmented.

Maxilliped 3 ( Fig. 7B View Fig ) margins and surface with short setae; ischiomerus length about 1.8 × width; inner, proximal twothirds 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.

Cheliped (pereopod 1) ( Fig. 7C 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. 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. 7D–G 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 3.7–4.0 × height (pereopods 2–4), about 3.0 × height (pereopod 5). Propodi unarmed, 2.5–3.2 × height. Dactyli similar, stout, strongly curved, falcate, evenly tapering, apices spiniform, corneous; flexor margin sparsely setose proximally; pereopod 2–4 dactyli 0.7 × propodus length; pereopod 5 dactylus 0.9 × propodus length.

Egg diameter 0.3–0.4 mm (in preservative).

Male: Similar to female but smaller maximum size ( Fig. 7H–Q View Fig ). Cheliped ( Fig. 7J View Fig ) palm dorsal margin length 1.2–1.3 × height. Abdomen narrow ( Fig. 7N 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 lateral and mesial margins, small tuft of short setae on step proximal to gently sinuous, glabrous, finely tapering, lanceolate tip ( Fig. 7O, P View Fig ). G2 short, simple, about one-fourth G1 length; exopod absent ( Fig. 7Q View Fig ).

Hosts. Holothurians and the ascidians, Herdmania grandis ( Heller, 1878)   and H. momus Savigny, 1816   ( Pyuridae   ). As is the case with the ascidian host of A. pregenzeri   , host records of A. holothuriensis   as H. momus   may referable to the similar species, H. grandis   , given that the latter apparently does not occur in southern Australia ( Kott, 2002). In Western Australia, A. holothuriensis   was frequently observed sharing the branchial chamber of its ascidian host with the caridean shrimp, Notopontonia platycheles Bruce, 1991   ( Palaemonidae   ); the crabs lived close to the inhalant siphon whereas the shrimps lived among the folds within the branchial chamber ( Berggren, 1999). Crabs were often found in male-female pairs, singly or in some cases with three crabs (male, two females) in the same ascidian.

Remarks. Austrotheres holothuriensis   occurs only in southern Australia, ranging from Western Australia to Victoria and Tasmania. Previous records of A. holothuriensis   from eastern Australia ( Pregenzer, 1988) are based on A. pregenzeri   new species. Features distinguishing A. holothuriensis   from A. pregenzeri   are discussed under the account of the latter.

The type series of A. holothuriensis   was collected from both ascidians and holothurians, of which the specimens from the latter host are larger ( Baker, 1907). Whether host type affects crab size remains to be determined, although A. pregenzeri   from eastern Australia, hosted by similar ascidians, attains a similar maximum size to A. holothuriensis   . The largest female type specimen (cl 8.3 mm, cw. 7.2 mm; SAM C1389; Fig. 7A–G View Fig ) is herein selected as the lectotype to fix the identity of the species.

A number of specimens of A. holothuriensis   were collected outside the host, corroborating Baker’s (1907: 178) observation that the “crab is able to swim, and probably does not spend all its time within the host”. It is unusual for the range of hosts occupied by pinnotherid species to span phyla. Whereas O. tridacnae   was thought to infect both molluscs ( Tridacna sp.   ) and ascidians, the single record from the latter host ( Adensamer, 1897) is based on a misidentification (see Remarks for O. tridacnae   and O. cynthiae   ). Austrotheres holothuriensis   , however, is confirmed from both holothurians and ascidians. Known obligate holothurian associates are conspicuously tomentose: Alain Manning, 1998   , Buergeres Ng & Manning, 1998   , Holotheres Ng & Manning, 1998   , Holothuriophilus Nauck, 1880   , and Trichobezoares Ng, 2018   . That these taxa are probably not all closely related suggests that the dense setation might be adaptive for holothurian occupation. Austrotheres holothuriensis   , however, has setose pereopod margins typical of other pinnotherids, but is otherwise largely glabrous. Notably, most records of A. holothuriensis   are from ascidians or outside of the host. Austrotheres holothuriensis   has only once been recorded from holothurians ( Baker, 1907) and the lack of subsequent holothurian records may be an observational artefact given that ascidians are more routinely dissected for taxonomic identification than holothurians. Alternatively, A. holothuriensis   may be only a facultative holothurian associate, accounting for both the low relative frequency of host records and differences in body setation compared to known obligate holothurian commensals. The American Opisthopus transversus Rathbun, 1893   , a temporary associate of holothurians, also lacks the body tomentum ( Campos & Manning, 2000).

Males mature by cl 3.3–3.6 mm. The cl 2.4 mm male (NMV J10740 View Materials ) is a juvenile: pleopods 3–5 are absent but the G1 is incompletely developed; by cl 3.3 mm (NMV J10739 View Materials ), the gonopods are fully developed. Juvenile females to about cl 5.4 mm have a narrow, male form abdomen. The smallest ovigerous female A. holothuriensis   examined is comparatively large (cl 9.0 mm, WAM C23498 View Materials ), but as in A. pregenzeri   , female A. holothuriensis   appear to be mature by about cl 6 mm judging from abdominal and pleopodal development. The northermost specimen of A. holothuriensis   (WAM C23502 View Materials , Shark Bay) and one reported from Edithburgh, South Australia ( Hale, 1927a), has a rhizocephalan parasite.

Distribution. Southern and western Australia, from Tasmania and Port Phillip Bay, Victoria, to Shark Bay, Western Australia; 6– 92 m.

SAM

South African Museum

AM

Australian Museum

NMV

Museum Victoria

WAM

Western Australian Museum

RV

Collection of Leptospira Strains

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Family

Pinnotheridae

Genus

Austrotheres

Loc

Austrotheres holothuriensis ( Baker, 1907 )

Ahyong, Shane T. 2018
2018
Loc

Ostracotheres holothuriensis

Ng PKL & Guinot D & Davie PJF 2008: 250
Ahyong ST & Brown DE 2003: 11
Berggren M 1999: 187
Takeda M & Konishi K 1989: 1222
1989
Loc

Pinnotheres obesus

Davie PJF 2002: 433
Schmitt WL & McCain JC & Davidson E 1973: 60
1973
Loc

Ostracotheres

Tesch JJ 1918: 287
1918
Loc

Pinnotheres holothuriensis

Davie PJF 2002: 433
Schmitt WL & McCain JC & Davidson E 1973: 6
Silas EG & Alagarswarmi K 1967: 1192
Hale HM 1927: 173
Tesch JJ 1918: 262
1918
Loc

Pinnoteres holothuriensis

Baker WH 1907: 177
1907
Loc

Pinnoteres obesa

Fulton SW & Grant FE 1906: 18
1906