Petrolisthes hastatus Stimpson, 1858

Werding, Bernd & Hiller, Alexandra, 2015, Description of a new species of Petrolisthes in the Indo-West Pacific with a redefinition of P. hastatus Stimpson, 1858 and resurrection of P. inermis (Heller, 1862) (Crustacea, Anomura, Porcellanidae), ZooKeys 516, pp. 95-108 : 97

Taxon classification Animalia Decapoda Porcellanidae

Petrolisthes hastatus Stimpson, 1858 Fig. 1

Petrolisthes hastatus Stimpson, 1858: 228, 241; 1907: 184, pl. 22 fig. 4. - Miyake 1943: 54, 62, figs 5, 6. - Haig 1964: 360 (partim); 1979: 124, fig. 5. - Johnson 1970: 13. - Nakasone and Miyake 1971: 5 (partim), pl. 1, fig. A. - Hsieh, Chan and Yu 1998: 307, figs 14D, 18 A–H. - Osawa and Chan 2010: 131, figs 98-102.

Material examined.

Indonesia: Snellius Expedition 1929-1930. RMNH.CRUS.D.56378, ca. 260 specimens, Sissie by Misool, beach, 06. Oct. 1929; RMNH.CRUS.D.56379, ca. 140 specimens; RMNH.CRUS.D.56380, ca. 60 specimens, Ambon, 11.-17.09.1930; RMNH.CRUS.D.56381, ca. 145 specimens; RMNH.CRUS.D.56382, ca. 90 specimens. Aloonf, beach and reef, 08.02.1930; RMNH.CRUS.D.56383, ca. 90 specimens, Tidore, strand, 24.-29.09.1929; RMNH.CRUS.D.56384, 9 males, 9 females (3ov), Pelee (by Misool), beach, 04.10.1929; RMNH.CRUS.D.56386, 1 male, Menado, 10.10.1930; RMNH.CRUS.D.56390, 1 male, Morotai, 03.-10.06.1930 RMNH.CRUS.D.56396, 2 spec. Bopyridae , Alsang, beach and reef, 08.02.1930; RMNH.CRUS.D.56397, 1 male, 1 female (ov), Los (by Misool), beach and reef, 03.-06.10.1929; RMNH.CRUS.D.56398, 4 males with Bopyridae , Tidore, beach, 24.-29.09.1929; RMNH.CRUS.D.56399, 1 male with Bopyridae , Paleleh, Celebes, beach, 21.0.1929; RMNH.CRUS.D.56400, 1 male, Maenado, 01. Oct. 1930; RMNH.CRUS.D.56401, 1 male, Ambon, 11.-17.09.1930; RMNH.CRUS.D.56402, 2 males with Bopyridae , Pelokan, Postiljon Island, beach and reef, 20.12.1929; RMNH.CRUS.D.56403, 1 male, near Koepang, strand, 25.11.1929; RMNH.CRUS.D.56404, 1 male, Tidore near Koepang, Tjabo, beach, 24.- 29.09.1929; RMNH.CRUS.D.56405, 1 male, Paleleh Celebes, beach, 21.08.1929; MNH.CRUS.D.56406, 1 male, Ake Salaka, Raoebaai Halmakeira, beach and reef, 28.05.1930; RMNH.CRUS.D.56407, 1 male, Taliaboe, Pasik Lpah,Solea Island), beach, 19.03.1930. Papua New Guinea. MNHN-IU-2013-9128, 1 male, Stn. PM08, 05°15'17.82" - 145°46' 38.91 E’’, Yabob Village, Gum River, 0-1m, 12.11.2012; MNHN-IU-2013-960, 1 male; MNHN-IU-2013-9539, 1 female (ov), Stn. PM41, 05°08.1'S - 145°49.3'E, Wonad Island, sandy beach and intertidal rocks, 0-1m, 27.11.-09.12.2012; MNHN-IU-2013-295, 1 male, Stn. PM12 05°00.2'S - 145°47.6'E, Rempi Area, S Dumduman Island, limestone rocky intertidal, 0-1m, 09.11.2012; MNHN-IU-2013-9615, 1 male, Stn. PM22, 05°04.7'S - 145°48.9'E Sek I, Night Tide, 14.11.2012. MNHN-IU-2013-9615, 1 male, Stn. PM22, 05°04.7'S - 145°48.9'E Sek I, Night Tide, 14.11.2012; MNHN-IU-11212, 1 male; Stn. VM46, 15°34'S- 167°12'E, Vanuatu, Aoré Island, 03.10.2006.

Measurements.

Largest male: CL 10.7 mm × CW 10.9 mm; largest female: CL 10.3 mm × CW 10.7 mm.

Description.

Carapace as broad as long or slightly broader than long, evenly rounded on branchial regions, broadest at posterior branchial level; surface covered with flattened, fine granules and faint plications. Front strongly produced, sinuously triangular, rostrum with a median sulcus, supraocular angle scarcely produced, depressed by a shallow groove. Orbits shallow; outer orbital angle rounded, scarcely produced, forming a low lobe with continuing hepatic margin; epibranchial angle accentuated but without notch or spine, continuing in a ridge along mesobranchial margin; branchial margin unarmed. Protogastric ridge forming a distinct crest, cervical grooves and regions slightly defined. Lateral walls with short, feathered setae.

Basal segment of antennular peduncle with faint transverse rugae; anterior margin rounded, with a distinct tooth at mesial corner and a rounded protuberance at lateral corner.

First movable segment of antenna with foliate, subquadrate projection without prominent tooth; second segment with a longitudinal granular crest ending proximally in a rounded tooth; third rounded, unarmed.

Chelipeds sub-equal. Merus with transverse, low granules on dorsal surface, anterior margin armed distally with a prominent, finger-shaped, rounded lobe; dorso-distal margin fringed with short setae. Carpus about 2.5 to 3 times longer than broad; dorsal surface covered with shallow, transverse rows of granules; anterior margin with 3 (rarely 4) wide-set, serrate-edged, hooked teeth, the proximal one normally the largest; posterior margin slightly curved outwards, granules along posterior margin enlarged, forming a crest terminating in a prominent, curved tooth; dorso-distal margin with short pubescence posteriorly.

Chelae large, broad and flattened; outer margin evenly arcuate and unarmed; dorsal surface covered with shallow, rounded granules; fingers broad, spineless, meeting at their entire length or slightly gaping in the larger chela, entire gape covered with a short pubescence.

Ischium of walking legs covered with feathered setae; merus spineless or with 1-3 irregularly-set spines and a fringe of feathered setae along the anterior margin; merus of L1 and L2 with a posterodistal spine. Carpus with a fringe of feathered setae on the anterior margin. Propodus and dactylus with scattered, feathered and long, simple setae; propodus ventrally with a distal triplet of movable spinules, and one additional spine at mid-distance; dactylus with 3 movable spines on posterior margin.

Variation.

The number of teeth on the anterior margin of the cheliped carpus may be reduced, the position of the lacking tooth is then marked by a small knob; in other cases a vestigial additional tooth is present.

Habitat.

Petrolisthes hastatus is a shallow water species. The specimens of the Snellius and Papua New Guinea expeditions were collected from intertidal or shallow subtidal (0.5 m depth) rocks and reefs. Haig (1979) and Osawa and Chan (2010) described the habitat of the species as intertidal, under rocks.

Distribution.

The species, as defined here, is restricted to the western Pacific, from Singapore, eastwards trough Indonesia and Papua New Guinea to Vanuatu. Northwards it occurs in Taiwan, and Ryukyu and Kikaijima, Japan.