Type material
Syntypes of Eupagurus dimorphus Studer, 1883, off Cape of Good Hope, South Africa, S.M.S. “Gazelle”, 34°13.6'S, 15°00.7'W, 211 m (Museum für Naturkunde zu Berlin, Germany). Syntypes of Parapagurus brevimanus Balss, 1911: Valdivia sta 167, New Amsterdam, 37°47’S, 77°33’E, 496 m, 1 Mar 1899 (Museum für Naturkunde zu Berlin, Germany: ZMB 16459). Syntypes of Sympagurus arcuatus johnstoni Hale, 1941: Tasmania, BANZARE sta 115 41°03’S, 148°42’E, 128 m (South Australian Museum, Adelaide, Australia: SAMA C4095). Syntypes of Sympagurus arcuatus mawsoni Hale, 1941: Macquarie Island, BANZARE sta 83, 54°42’S, 158°54’E, 69 m (South Australian Museum, Adelaide, Australia: SAMA C4094).
Type locality
South Atlantic Ocean: off Cape of Good Hope, South Africa, 34°13.6'S, 15°00.7'W, 211 m.
Description
Gills with lamellae deeply divided. Shield usually as broad as long; dorsal surface often weakly calcified medially; anterior margins concave; lateral projections subtriangular, with small terminal spine. Rostrum rounded, with broad low dorsal ridge
Ocular peduncles more than half shield length. Ocular acicles subtriangular, terminating in strong simple or occasionally bifid spine. Corneae weakly dilated.
Antennular peduncle exceeding distal margin of cornea by nearly full length of ultimate segment.
Antennal peduncle at most slightly exceeding distal margin of cornea. Fourth segment with small dorsolateral distal spine. Second segment with dorsolateral distal angle produced, terminating in strong bifid or multifid spine. Acicle curved outwardly (dorsal view), usually not exceeding distal margin of cornea; mesial margin setose, armed with 13-19 strong spines. Flagellum with numerous short setae < 1 to 2 articles in length.
Maxillule with external lobe obsolete or weakly developed, internal lobe with usually 4 long setae distally. Epistomial spine short and straight, sometimes absent. Sternite of third maxillipeds with strong spine on each side of midline.
Chelipeds markedly dissimilar, covered with moderately dense simple and plumose setae. Right cheliped massive. Chela usually operculate, proportions and armature strongly affected by size and sexual dimorphism; dorsolateral margin in dorsal view evenly convex or subsemicircular in females and males of similar size, or straight in large males (sl > 9.0 mm); armature of dorsal surface consisting of numerous sharp to blunt spines or small tubercles. Fingers strongly curved ventromesially. Dactyl with ventromesial surface concave. Palm with dorsomesial and dorsolateral margins each well delimited by row of spines.
Left cheliped well calcified. Palm with dorsomesial, dorsolateral, and often dorsomedian rows of small tubercles or spines. Carpus with dorsal row of spines.
Ambulatory legs similar except for longer segments on right, and for armature on meri, carpi and propodi frequently more developed on right. Dactyl shorter than propodus, with ventromesial row of 15-20 strong spinules, dorsal row of long setae, and 3 or 4 short, dorsomesial oblique rows of setae distally. Carpus with dorsal row of spines. Anterior lobe of sternite of second legs with 1-3 small submarginal spines, setose.
Fourth pereopod semichelate. Dactyl terminating in sharp corneous claw. Propodal rasp with 2-5 irregular rows of ovate scales.
Uropods and telson strongly asymmetrical. Telson with weak lateral indentations; terminal margin divided into 2 lobes by wide, shallow, rounded (U-shaped) cleft; lobes armed distally with short corneous spines.
Male first gonopod with moderately concave distal lobe. Second gonopod with distal segment spatulate, basal segment occasionally with short exopod.
Females lacking first pleopods, or occasionally with rudimentary paired or unpaired first pleopods; with vestigial right second pleopod.
Size range.— Males, 2.2-29.5 mm. Females, 2.2-22.0 mm. Ovigerous females, 3.9-29.5 mm.
Color.— Lemaitre (2000: 217, pl. 7) indicated that the overall color of the body is cream. Based on additional photographs obtained during this study, and color patterns still present in formalin-preserved specimens, a more detailed account of coloration is now possible.
Shield with light orange-red areas on calcified portions. Ocular peduncles with orange-red stripe on dorsal faces; ventral faces orange-red. Antennal peduncle with light orange-red spot on lateral face of second segment, and orange stripe on lateral faces of fourth and fifth segments. Right cheliped orange-red with cream spines or tubercles, orange coloration becoming lighter or cream on dorsomedian areas of carpus and chela. Left cheliped orange-red except for white or cream spines, tips of fingers, dorsomesial surface of palm, and dorsomedian and mesial surfaces of carpus; merus with orange-red ventral surface and dorsomesial and dorsolateral stripes. Ambulatory legs with orange-red dorsal and ventral surfaces, and cream-white on lateral and mesial surfaces. Abdomen, uropods and telson orange.
Morphological variations
These have been described in detail by Lemaitre (1989), and Lemaitre & McLaughlin (1992).
Habitat and symbiotic associations
Commonly found living in gastropod shells, usually with an actinian or zoanthid polyp attached to the shell. Also found in colonies of Epizoanthus species. Young individuals are sometimes found living in scaphopod shells (ZHADAN, pers. comm.).
Distribution
Southern hemisphere from 22°S to 57°S; in the Atlantic Ocean possibly as far north as Ascension Island. Depth: 91 to 1995 m.
Taxonomic remarks
As indicated by Lemaitre (1989: 77), it is questionable whether the specimen reported by A. Milne-Edwards & Bouvier (1893) from the Caribbean as Parapagurus dimorphus, represents Studer’s Sympagurus dimorphus. This species is known only from high latitudes of the southern hemisphere.
In his description of Parapagurus brevimanus, Balss (1911) listed two specimens, a male and a female, which are syntypes, since he did not select a hootype. Examination of the syntype lot (Museum für Naturkunde zu Berlin, Germany: ZMB 16459) reveals that it actually comproses seven specimens, all of which are S. dimorphus. Hale’s (1941) two subspecies of Sympagurus arcuatus (S. a. johnstoni, and S. a. mawsoni) were determined by de Saint Laurent (1972) to be synonyms of S. dimorphus, and based on Hale’s descriptions, Lemaitre (1989) concurred.
Manning & Chace (1990) believed Eupagurus modicellus Stebbing, 1914 described from Ascension Island, South Atlantic, to be Sympagurus dimorphus. However, as stated by Lemaitre & McLaughlin (1992), the specimen used and illustrated by Stebbing (1914, pl. 26, fig. D), apparently lost, is likely a juvenile specimen that can only be questionable assigned to S. dimorphus.
The larval development of parapagurid species remains unknown, therefore the assignments to S. dimorphus of planktonic larvae (de Saint Laurent-Dechancé, 1964, as Parapagurus sp. 2; Williamson & von Levetzow, 1967, as “Species S.A. 1”; Bacardit, 1987, as Parapagurus dimorphus), are speculative.
