IUCN threat status:

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Comprehensive Description

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Description

Pagurus albidianthus sp. nov. (Fig. 65, Pl. 6, fig. 3)

 

(?) Pagurus n. sp. 1: Rainer 1981: 37.

 

Pagurus sp. 'pink and white': Probert et al. 1979: 381.

 

Pagurus n. sp. A: Schembri & McLay 1983: 28, 32, fig 19; Schembri 1988: 93, 99.

 

TYPES:

 

Holotype: male (S1= 7.5 mm) from NZOI Stn B628, NIWA holotype H-715.

 

Paratypes: 1 male (sl = 7.7 mm) from NZOI Stn B628, NIWA paratype P-1168; 1 male (sl = 10.2 mm), 2 females ( sl = 6.5, 6.7 mm), Cloudy Bay, coll. G. Olsen, 1987, 2-7 m, NMNZ Cr 8217; 1 female, 1 ovigerous female (sl = 2.4, 3.9 mm), Hawke Bay, coll. C. Duffy, 19.1.95, 4 m, MNHN Pg 5851; 1 male, 1 female (sl = 2.3, 4 mm), off Waitarere, 40°23.2'S, 175°13.3'E, coll. T. Willis, 6.5.94, 4.1 m, USNM 268573; 40°27.1'S, 175°12.4'E, coll. T. Willis, 10.4.94, 5.5 m, 1 male, 2 females (sl = 2.9-3.6 mm) NHM 1999.874-876.

 

TYPE LOCALITY: NZOI Stn B628, off Hokitika, 42°55.5'S, 170°27'E, 28 m.

 

OTHER MATERIAL EXAMINED:

 

NZOI Stns: B628, 8 males (sl = 3.6-7.2 mm), 6 females (sl = 3.8-4.2 mm), 1 ovigerous female (sl = 4.2 mm); B661, 2 females (sl = 3.6, 4.0 mm); B662,1 male (sl = 4.8 mm); B671, appendages only.

 

NMNZ collections: Off Waitarere, 40°21.8'S, 175°13.4'E, toll. T. Willis, 6.5.94, 3.8 m, 2 males, 3 females (sl = 1.6­3.7 mm), Cr 9769; 40°24'S, 175°13.1'E, coll. T. Willis, 11.4.94, 5.2 m, 1 male (sl = 3.7 mm), Cr 9770.

 

PMBS collections: MU 67-68, Blueskin Bay, 29.5.67, 4.6­6.1 m, 2 males (3.7, 4.0 mm), 1 ovigerous female (3.7 mm).

 

PMcL collection: Great Omaha Bay, Stn C37, 1 female (sl = 3.4 mm); Off Waitarere, 40°25'S, 175°12.8'E, coll. T. Willis, 11.4.94, 6.1 m, 1 male (sl = 4.3 mm); 40°27.8'S, 175°11.9'E, coll. T. Willis, 10.4.94, 9.8 m, 1 male (sl = 2.6 mm), 1 ovigerous female (sl = 3.7 mm).

 

DESCRIPTION: Shield slightly broader than long to slightly longer than broad; anterior margin between rostrum and lateral projections concave; anterolateral margins sloping or slightly terraced; posterior margin truncate or rounded; dorsal surface sometimes with few scattered setae. Rostrum usually roundly to subacutely triangular, without terminal spine, but occasionally with median tubercle and tuft of setae posteriorly. Lateral projections obtusely triangular or rounded, with or without small marginal or submarginal spinule.

 

Ocular peduncles moderately short, approxi­mately 0.55-0.75 length of shield, corneal diameter 0.27-0.35 peduncular length. Ocular acicles roundly subrectangular, with 2-6 spines on terminal margin.

 

Antennular peduncles over-reaching corneas by 0.25-0.75 length of ultimate segment. Ultimate seg­ment with few shorter setae on dorsal surface

 

Antennal peduncles reaching nearly to or slightly beyond distal margin of corneas. Fifth and fourth seg­ments with few scattered setae. Third segment usu­ally with small spine at ventrodistal angle. Second segment with laterodistal projection broad, reaching beyond proximal margin of fourth segment, with simple or bifid terminal spine, mesial margin with 5­7 small teeth; dorsomesial distal angle with prominent tooth. First segment with 1 prominent tooth on ventrolateral margin. Antennal acicle reaching to proximal half of ultimate peduncular segment, slightly arcuate, terminating in acute tooth, mesial margin with sparse row of setae. Antennal flagellum much shorter than outstretched right cheliped, with 1 or 2 short and 1-3 slightly longer setae every article.

 

Maxillule with external lobe of endopod mode­rately well developed, not recurved. Ischium of third maxilliped with 1 or 2 accessory teeth on crista dentata. Sternite of third maxillipeds unarmed and without median concavity.

 

Chelipeds grossly unequal. Right cheliped with dactyl approximately equalling length of palm; cutting edge with row of calcareous, distinct or nearly obsolete teeth, terminating in small corneous or calcareous claw; dorsal surface with scattered small tubercles and few setae, with row (more distinct in small specimens) of small, subacute tubercles in midline proximally but curving laterad of midline and extending nearly to tip; dorsomesial margin with regular or irregular row of low, broad, flattened teeth; ventral surface with few setae. Palm 0.65-0.75 length of carpus; dorsomesial margin with irregular row of small, often flattened denticles, angular dorsomesial face with numerous small tubercles, delimited from weakly convex dorsal surface by row of slightly stronger, subacute to acute tubercles appearing as continuation of median row of dactylar tubercles and in large specimens by longitudinal weak depression; dorsal surface covered, but not densely, with very small tubercles or granules; dorsolateral margin with row of small denticles, becoming distinct teeth (in small specimens) on fixed finger and extending almost to tip; mesial, lateral and ventral surfaces minutely to prominently tuberculate or granular, tubercles strongest on mesial face; cutting edge of fixed finger with row of small, sometimes nearly obsolete, calcareous teeth and 1 or 2 more prominent teeth medially, terminating in small corneous claw. Carpus approximately as long as merus; dorsomesial margin with irregular single or double row of very small denticles or teeth, sometimes separated from remainder of dorsal surface by weak longitudinal depression; dorsal midline with slightly stronger, longitudinal single or double row of spines or tubercles, dorsolateral margin not delimited, dorso­lateral surface with numerous subacute or acute tubercles and granules; dorsodistal, distomesial and distolateral margins each often with row of very small denticles or tubercles; mesial, lateral and ventral surfaces minutely tuberculate. Merus triangular; few setae on dorsodistal margin, dorsal surface with 3 o 4 short, transverse ridges and moderately short setae; ventromesial and ventrolateral margins each with row of tiny denticles or tubercles; ventral surface granular or tuberculate. Ischium unarmed but with few moderately long setae on ventral margin.

 

Left cheliped with dactyl exceeding length of palm by 0.25-0.45 own length; cutting edge with row of very fine corneous teeth, terminating in small corneous claw; sometimes with hiatus between dactyl and fixed finger; dorsomesial margin of dactyl unarmed or with row of denticles at least in proximal half, dorsal midline usually slightly elevated and often with 1 or 2 short rows of acute tubercles in proximal half; dorsal, mesial, and ventral surfaces with scattered moderately long setae. Palm 0.50-0.65 length of carpus; usually subtriangular in cross-section, sometimes only angularly convex, dorsal surface commonly slightly elevated in midline, not forming distinct ridge or crest, dorsal surface covered with acute and subacute tubercles or spinules, extending onto proximal half of fixed finger, dorso­lateral margin with row of small or very small, sub­acute or blunt denticles, usually not extending to tip of fixed finger, dorsomesial margin not delimited or with irregular row of protuberances or small teeth. Carpus approximately as long to slightly longer than merus; dorsolateral margin with short row of very small spines or teeth, dorsodistal margin unarmed, tuberculate, or with strong tooth, sometimes double, dorsomesial margin with single or double row of small teeth; ventral, mesial, and lateral faces with low, sometimes tuberculate ridges and setae; ventromesial margin with row of small to very small denticles or spinulose protuberances, ventrodistal margin with row of very small tubercles, at least laterally. Merus with short, transverse rows of setae on dorsal margin; ventromesial margin with row of small or very small denticles, ventrolateral margin unarmed or with few tiny denticles; ventral surface with tiny, blunt or acute tubercles and scattered setae. Ischium sometimes with few small or minute tubercles on ventromesial margin.

 

Ambulatory legs similar from left to right. Dactyls 1.10-1.50 as long as propodi, in dorsal view straight, in lateral view slightly arched; termi­nating in strong corneous claws; dorsal margins each with row of low protuberances and stiff bristles, increasing in length distally; lateral and mesial faces each with longitudinal sulcus, often quite prominent, at least in proximal 0.65, lateral faces often also with dorsal and ventral row of widely spaced fine setae, mesial faces with row of short setae dorsally and few setae ventrally; mesioventral or ventral surfaces each with 18-21 small, closely spaced spiniform setae, increasing in length distally. Propodi 1.10-1.15 longer than carpi; dorsal surfaces each with 1 to several irregular rows of spinulose protuberances or tubercles (strongest on second pereopods), frequently accom­panied by moderately short, spiniform bristles; lateral faces often tuberculate, in smaller specimens often only minutely so; ventrodistal margins each usually with 1 or 2 tubercles, ventral surface with row of blunt or spinulose protuberances and short bristles. Carpi 0.75-0.95 length of meri; each with row of small teeth or spinulose tubercles on dorsal surface, becoming strongest at distal angles and accompanied by very short, spiniform bristles and sparse short setae, but much less developed in small specimens (e.g., sl < 3.4 mm); lateral faces sometimes with few small, spinulose tubercles at or near distal margin and median longitudinal row of tufts of setae. Meri each with series of transverse rows of short to moderately long setae on dorsal surfaces; ventromesial and ventrolateral margins each with low, sometimes spinulose protuberances and short setae, or with row of distinct, small spines particularly on second pereopods. Ischia with few setae dorsally and ven­trally. Fourth pereopods semichelate; propodal rasp with single row of corneous scales; dactyl with preungual process as base of claw, developed in larger specimens (s1 > 4.0 mm). Sternite of third pereopods with few long marginal setae on roundly subrect­angular anterior lobe.

 

Sternite of fifth pereopods developed anteriorly as 2 laterally subovate lobes separated by broad, shallow, median depression, anterior margins each with row of moderately long setae. Second abdomi­nal segment in both sexes with 2 ventral prominent protuberant fleshy lobes, left largest. Males with paired gonopores; 3 unequally biramous unpaired pleopods, pleopods 3 and 4 with exopods moderately well developed, endopods rudimentary, pleopod 5 with exopod moderately well developed, endopod vestigial or absent. Females with paired gonopores, 4 unpaired pleopods, pleopods 2 to 4 with both rami well developed, pleopod 5 with exopod well developed, endopod markedly reduced.

 

Uropods asymmetrical; exopods and endopods both with well-developed rasps. Telson with posterior lobes slightly asymmetrical, separated by moderately broad median cleft; terminal margins rounded, with several large, calcareous teeth interspersed with smaller teeth, extending onto chitinous or weakly calcareous lateral margins.

 

COLOUR: Ocular peduncles and antennules light brown; antennae light brown with faint white bands. Chelipeds and ambulatory legs with pink ground colour tending to white and marked with darker pink longitudinal stripes (modified from Schembri & McLay 1983). Small specimens almost uniformly white (C. Duffy, field notes).

 

 

VARIATIONS: Although our sample size was quite small, variations in armature that appeared to be size related were observed. In small specimens (sl < 3.5 mm), the armature of chelipeds and ambulatory legs is appreciably weaker than depicted in the illu­strated paratype (s1 = 7.7 mm) and seen in the holo­type and other larger specimens. Particularly note­worthy is the strength of tubercles on the mesial face of the palm of the right cheliped, and the multiple rows of tubercles on the dorsal and lateral faces of the propodi of the second and third pereopods. Also, in large specimens the sulci on the lateral faces of the pereopodal dactyls are flanked by small tubercles, not seen in small specimens. Two variations that do not appear to be related to size are the armature of the terminal margins of the ocular acicles, and the shape of the rostrum. While small specimens frequently have from two to four teeth on the terminal margins of the ocular acicles and larger specimens a greater number, the holotype (sl = 7.5 mm) also only two teeth on one acicle and three on the other. Although usually broadly triangular, in at least one specimen the rostrum is broadly rounded. The slight protuberance posterior to the rostral tip is seen to a lesser extent in the holotype, and is more frequently represented by a tuft of setae.

 

REPRODUCTION: Ovigerous females were represented in our collection by only three individuals actually still carrying eggs, and one whose eggs had just been released. These egg-bearing females, all with shield lengths measuring between 3.1 and 3.7 mm, were collected in January, April, and May from the east coast of North and South Islands; however, the female (sl = 4.2 mm) from NZOI Stn 628 on the west coast of South Island had just released its eggs at the time of capture in October. It is premature to speculate as to whether reproductive periods for this species vary from west to east. The female from Hawke Bay, the largest of the ovigerous females, was also carrying the largest number of eggs, in excess of 200. These eggs, which were in an early stage of development, measured 0.40-0.46 mm in diameter.

 

HABITAT: In the Otago region, this species was found on the inner shelf, mainly on sand, and frequently occupied shells of Umbonium. Schembri (1988) reported it to be exclusively a nearshore inhabitant.

 

ETYMOLOGY: From the Latin albus, meaning white, and dianthus meaning pink, and referring to the colour of this species.

 

REMARKS: Although P. albidianthus has multifid ocular acicles as in some other shallow-water New Zealand species of Pagurus, it is readily distinguished from them by the armature of its chelipeds and ambulatory legs. The chelipeds of P. albidianthus are provided only with small tubercles or granules whereas P. traversi and P. novizealandiae have chelipeds armed with prominent teeth or tubercles. The ambulatory legs however, provide the most diagnostic characters. In P. albidianthus the dactyls are longer than the propodi and each has a longitudinal sulcus, usually quite prominent, on the mesial and lateral face; the propodi are armed with spinulose protuberances dorsally and often laterally. In P. novizealandiae the dactyls are approximately equal to the length of the propodi and ornamented dorsally and ventrally with tufts of long setae, those of the third pereopods forming a very dense fringe. The dactyls of P. traversi are shorter than the propodi and lack the longitudinal sulci on the mesial and lateral faces.

 

Pagurus albidianthus is morphologically most similar to Pagurus kaiensis McLaughlin, 1997 from the Kai Islands of Indonesia, sharing the general mor­phology of the chelipeds and ambulatory legs. The New Zealand species is immediately distinguished from the Indonesian species by its multifid ocular acicles. The antennular and antennal peduncles are also shorter in P. albidianthus than in P. kaiensis, and there are more spiniform bristles on the ventral mar­gins of the ambulatory dactyls in the former species.

 

 

RECORDS FROM NEW ZEALAND: On the west coast north of Auckland to southwest of Hokitika; eastern North Island from Great Omaha Bay to Otago; 3-28 m.

 

 

DISTRIBUTION: Known only from New Zealand.”

 

 

(Saint, Laurent et al, 2000: 199-206)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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