“Goreopagurus poorei sp. nov.
Figures 1–3
Michelopagurus n. sp.—Koslow and Gowlett-Holmes, 1998: 32. Michelopagurus sp.—Poore et al., 1998: 71.
Material examined. Holotype. Australia, Tasmania, 84 km SSE of SE Cape, “J1” seamount, 44û16.2´S, 147û19.8´E, 1300 m, 27 Jan 1997 (CSIRO stn SS01/97 37), NMV J44757 (male, 5.2 mm).
Paratypes. Australia, Tasmania, off Freycinet Peninsula, 41û58.6´S, 148û38.9´E, 500 m, 27 Jul 1986 (stn SLOPE 47), NMV J17433 (2 males, 3.6, 4.2 mm). 85.4 km SSE of SE Cape, “Main Pedra” seamount, 44û15.6´S, 147û06.0´E, 741 m, 21 Jan 1997 (CSIRO stn SS01/97 03), NMV J44807 (5 males, 2.9–3.6 mm); NMV J44767 (2 ovigerous females, 2.4, 2.7 mm). 83.8 km SSE of SE Cape, “J1” seamount, 44û16.2´S, 147û19.8´E, 987 m, 27 Jan 1997 (stn SS01/97
36), NMV J448051 (male, 2.4 mm; ovigerous female, 2.6 mm); USNM 1007889 (female, 3.7 mm). 84.0 km SSE of SE Cape “J1” seamount, 44û16.2´S, 147û19.8´E, 1300 m, 27 Jan 1997 (stn SS01/97
37), NMV J52355 (3 males, 3.3–4.9 mm; ovigerous female, 3.2 mm). 85.8 km SSE of Cape, “B1” seamount, 44û18.6´S, 147û16.2´E, 1150 m,
28 Jan 1997 (stn SS01/97 43), NMV J448021 (male, 3.0 mm). 69.7 km SSE of SE Cape, “Mackas” seamount, 44û12.6´S, 147û02.4´E, 640 m,
29 Jan 1997 (stn SS01/97 50), NMV J44808 (male, 3.0 mm). 65.5 km SSE of Cape, SE “Andys” seamount, 44û10.8´S, 147û00.0´E, 800 m, 29 Jan 1997 (stn SS01/97 56), NMV J44804 (5 males, 2.9–4.7 mm ), USNM 1007890 (2 males, 2.6, 3.9 mm). 65.1 km SSE of Cape, SE “Andys” seamount 44û10.8´S, 146û59.4´E, 900 m, 29 Jan 1997 (stn SS01/97 57), NMV J44809 (male, 3.0 mm).
Other material. Australia, Tasmania. 66.5 km SSE of Cape, SE “Andys” seamount, 44û11.4´S, 148û57.0´E, 620 m, 29 Jan 1997 (stn SS01/97 55), NMV J44806 (2 males, 2.9, 3.4 mm). 65.6 km SSE of Cape, SE “Andys” seamount, 44û10.8´S, 147û00.0´E, 800 m, 29 Jan 1997 (stn SS01/97 56), NMV J44764 (ovigerous female, 2.6 mm). Exact locality not recorded (CSIRO cruise 1/97), NMV J44810 (male, 2.4 mm; 3 ovigerous females, 2.4–3.3 mm).
Description. Gill lamellae distally quadriserial (Fig. 1a). Shield (Fig. 1b) as broad or broader than long; anterior margins between rostrum and lateral projections weakly concave; anterolateral margins sloping or slightly terraced; posterior margin roundly truncate, frequently with slight median con-cavity; dorsal surface with few sparse tufts of setae. Rostrum (Fig. 1b–d) acutely or obtusely triangular, with or without small terminal spine or spinule, sometimes also with 1 small spine or spinule laterally on one side. Lateral projections obtusely triangular, each with small submarginal spine.
Ocular peduncles 0.4–0.6 length of shield, moderately stout and with distinct medial constriction; dorsomesial surface with 2 or 3 short, transverse rows of stiff setae in distal half, 1 sparse tuft of setae on dorsal surface; corneal diameter 0.4–0.5 of peduncular length. Ocular acicles narrowly and acutely triangular, with strong submarginal spine; separated basally by at least basal length of 1 acicle.
Antennular peduncles overreaching distal margins of corneas by at least entire length of ultimate segments. Ultimate segment with row of long, stiff setae at dorsodistal margin and additional few scattered, short setae. Penultimate segment with few scattered setae. Basal segment with slender spine on lateral margin of statocyst lobe.
Antennal peduncles overreaching distal corneal margins by 0.7 to entire length of ultimate segments. Fifth segment with several sparse tufts of setae. Fourth segment with few scattered setae. Third segment with prominent, acute spine at ventrodistal margin. Second segment with dorsolateral distal angle produced, terminating in acute spine, mesial margin with 3–7 small spines or spinules (occasionally only weakly apparent) and usually with 1 prominent spine on lateral margin in distal half; dorsomesial distal angle with well developed spine. First segment usually with small spine on dorsolateral distal margin and 1 spine on ventrolateral margin distally. Antennal acicle long, reaching beyond midlength of ultimate peduncular segment, arcuate, terminating in small spine; mesial surface with row of tufts of stiff setae. Antennal flagella long, but usually not overreaching tip of outstretched right cheliped; articles each usually with 2 or 3 short (< length of 1 article) setae.
Third maxilliped with 2 or 3 spines on basis; ischium with accessory tooth on well developed crista dentata; merus with 1 spine on ventral margin and 1 spine at dorsodistal margin. Sternite of third maxillipeds with tiny spinule on either side of midline.
Right cheliped of large males very elongate, somewhat shorter in females and small males; palm, fixed finger and dactyl slender, dorsoventrally compressed. Dactyl 0.7–0.9 length of palm; cutting edge with 1 moderately prominent calcareous tooth at midlength, 3 or 4 smaller calcareous teeth proximally and row of very small corneous teeth in distal 0.3, terminating in small corneous claw, but often worn; dorsomesial margin with row of very small spines, spinules or spinulose tubercles, dorsal surface somewhat elevated in mid-line, occasionally unarmed but usually with single or double row of very small spinules, tubercles or protuberances. Palm slightly shorter than carpus; dorsomesial margin not distinctly delimited, rounded mesial face with irregular rows of very small tubercles, granules or spinules; dorsolateral margin with row of very small spinules, dorsal surface with covering of very small spinules or granules and very short setae, most prominent in females and small males, occasionally additional short row of slightly larger spinules or granules adjacent to dorsolateral margin proximally, dorsal midline with 1 or short, longitudinal row of 2–4 small spines proximally; cutting edge of fixed finger with entire calcareous margin in proximal half, usually few individual calcareous teeth distally, terminating in corneous claw, often worn. Carpus (Fig. 2b, c, e) longer than merus, produced ventrally, particularly in large males; dorsomesial margin weakly to notably expanded, armed with row of prominent, blunt or acute spines, dorsodistal margin with 1 or 2 spines mesially, dorsal surface usually with numerous very small tubercles, granules or low protuberances and scattered setae, dorsolateral margin usually delimited at least distally by row of small granules or spinules; mesial face usually sloping, often appearing somewhat concave, ventromesial margin unarmed; ventrolateral margin with row of granules, tubercles or spines. Merus subtriangular; dorsodistal margin sometimes with 1 spine, dorsal surface with few low protuberances and setae; ventromesial and ventrolateral margins each with row of spines, ventral surface usually with few scattered spines and sparse, moderately long setae. Ischium with row of small spinules on ventromesial margin, at least proximally, and scattered moderately long setae.
Left cheliped long and slender, but not reaching much beyond proximal margin of palm of right in large males; dactyl and fixed finger weakly arched ventrally. Dactyl 1.5–2.0 length of palm; cutting edge with row of tiny corneous teeth, terminating in small corneous claw; dorsal surface elevated in midline and with sparse row of setae; dorsomesial margin with irregular row of small spinules or tubercles, at least in proximal half. Palm 0.4–0.6 length of carpus; dorsomesial margin with irregular row of small spines or tubercles, dorsal surface usually with covering of very short setae, midline prominently elevated and armed with row of small spines, extending onto fixed finger but usually not to tip, dorsolateral margin with row of small spinules or granules, adjacent dorsal surface granular; ventral surface with scattered tufts of long setae; cutting edge of fixed finger with row of very small calcareous teeth, interspersed distally with corneous teeth. Carpus slightly shorter to slightly longer than merus; dorsal surface somewhat flattened, dorsomesial and dorsolateral margins each with row of spines, strongest distally; mesial face with numerous protuberances and setae, distomesial margin with few spinules ventrally, sometimes extending onto ventromesial margin; ventral surface with few spinules or low protuberances and scattered, moderately long setae; lateral face unarmed, ventrolateral margin with row of spines. Merus subtriangular; dorsal surface with few low protuberances and sparse setae; ventromesial and ventrolateral margins each with row of spines and moderate to long setae, ventral surface frequently with moderately dense covering of short setae. Ischium with row of small spines or spinules on ventromesial margin and scattered moderately long setae.
Ambulatory legs similar from left to right. Dactyls 1.2–1.4 length of propodi; dorsal margins each with sparse row of short stiff setae; ventral margins each with row of 10–13 corneous spines; lateral faces each with weak longitudinal sulcus; mesial faces each with row of corneous spinules dorsally. Propodi 1.3–1.7 length of carpi; each with 1 or 2 corneous spinules at ventrodistal angle and row of widely-spaced, small corneous spinules on ventral margin, dorsal surfaces each with low protuberances and sparse stiff setae or bristles. Carpi each with small spine at dorsodistal margin, few stiff setae arising from low protuberances on dorsal surface, 1 or 2 stiff setae on ventral margin distally and occasionally also medially. Meri with low protuberances and sparse tufts of setae on dorsal surfaces, tufts of stiff setae and occasionally 1 to few, often spinulose, protuberances or small spinules on ventral surfaces, distal angles of second pereopods occasionally each with acute spine (not present in holotype). Ischia unarmed but with few stiff setae or bristles. Anterior lobe of sternite of third pereopods subsemicircular with stiff bristles on anterior margin.
Fourth pereopods with small preungual process at base of claw.
Males without sexual tube on either coxa of fifth pereopods; unpaired left pleopods 3–5 with endopods rudimentary, very rarely with vestigial second pleopod present. Females with paired and modified first pleopods; second to fourth unpaired left pleopods with endopods stout, egg-bearing, exopods long, slender and usually non egg-bearing; fifth pleopod as in males. Uropods markedly asymmetrical. Telson with transverse indentation; posterior lobes separated by moderately shallow median cleft, terminal margins slightly oblique to nearly horizontal, each with 3–5 small spines, lateral margins sometimes delimited by narrow chitinous band.
Colour (in preservative). Cephalothorax, carpi and meri of chelipeds and entire ambulatory legs with tint of reddish-orange; chelas dirty-white. Ocular peduncles dull red.
Distribution. Tasmania, off Freycinet Peninsula and seamounts SSE of Southeast Cape: “Andys”, “B1”, “J1”, “Main Pedra”, and “Mackas” seamounts; 500–1300 m depth.
Etymology. For Gary C. B. Poore, Curator of Crustacea at Museum Victoria, Melbourne, Australia, in recognition of his major contributions to crustacean systematics.
Remarks. On the basis of a few individuals, this species was tentatively but incorrectly assigned to Michelopagurus by P.A. McLaughlin in correspondence to Koslow and Gowlett-Holmes (1998).
Individuals of Gorepa gurus poorei are significantly larger than those of G. piercei and G. garthi. Specimens range in shield length from 2.4 to 5.2 mm, whereas the specimens of G. piercei and G. garthi, all sexually mature and including some ovigerous females recorded by McLaughlin (1988) and McLaughlin and Haig (1995) range from 0.5 to 1.8 mm, and 1.3 to 2.3 mm, respectively. McLaughliin (1988) and McLaughlin and Haig (1995) attributed variation of the right cheliped, particularly the carpus, of G. piercei and to some extent also G. garthi, to sexual dimorphism. Although specimens of G. poorei as small as those of G. piercei and G. garthi are not known, it appears that in G. poorei variations of the carpus are related to allometric growth rather than sexual dimorphism. The dorsomesial margin of the carpus in large specimens of G. poorei develop a more marked flare (Fig. 2a–d) than in smaller specimens; the strength and sharpness of the spines on the dorsomesial and ventrolateral margins of the carpus diminish with increased size.
Not only is G. poorei immediately distinguishable from P. piercei and P. garthi by the absence of male sexual tubes, the gill lamellae are distally quadriserial rather than biserial. Although uniformity in gill structure is usual in most genera, Goreopagurus is not the only genus in which both biserial and distally quadriserial gills are found. A similar condition exists in the parapagurid genus Sympagurus (Lemaitre, in press: fig. 1) and the pagurid Xylopagurus A. Milne-Edwards, 1880 (pers. obs.). McLaughlin and de Saint Laurent (1998) reported that gill lamellae vary from deeply quadriserial to only distally so within a single species or even within a single individual. De Saint Laurent-Dechancé (1966) considered quadriserial gills more primitive than biserial gills, thus one might envision the evolution of the gill lamellae from completely divided to distally divided to entire (biserial). In the case of the three species of Goreopagurus, the most primitive species then would be G. poorei. Support for this hypothesis is also apparent in the transition from no sexual tubes in G. poorei to very short tubes in G. garthi to short tubes in G. piercei.”
(Lemaitre & McLaughlin, 2003: 222-226)
