Paguristes antennarius Rahayu, 2006

Rahayu, Dwi Listyo, 2007, The hermit crabs Paguristes Dana, 1851 s. l. (Crustacea, Decapoda, Anomura, Diogenidae) from the western Indian Ocean, Zoosystema 29 (3), pp. 515-534 : 517-520

Paguristes antennarius Rahayu, 2006

Paguristes antennarius Rahayu, 2006: 369 , figs 13-15.

MATERIAL EXAMINED. — Madagascar. 15°18.3’S, 46°10.3’E, 500-550 m, 8.XI.1972, 1 ♂ (2.8 mm) ; 1 ♀ (4.6 mm). — 21°24.5’S, 43°13.5’E, 640-720 m, 26.XI.1973, 1 ♂ (6.8 mm). — 21°25.5’S, 43°14.5’E, 425-550 m, 26.XI.1973, 2 ♂♂ (6 and 6.8 mm); 1 ♀ (5.6 mm). — 15°18’S, 43°02.2’E, 640-660 m, 1.XII.1973, 2 ♀♀ (4.3 and 6.8 mm) .

DISTRIBUTION. — Indonesia and Madagascar, from 425 to 720 m.

REMARKS

Rahayu’s (2006) description of P. antennarius did not include a comparison with P. miyakei Forest & McLaughlin, 1998 , despite these two species having several characters in common, such as the long and dense setation on the antennal flagella, the short ocular peduncles, which are only half the length of the shield or a little longer, and the covering of small spinulose tubercles on mesial faces of dactyls of chelipeds. The comparison with specimens of P. miyakei deposited in MNHN showed certain differences. The two species differ in the armament of the second and third pereopods and the mesial faces of the dactyls of the chelipeds. The ventral margins of dactyls of the second and third pereopods of P. miyakei each have a row of 20-28 small corneous spines and the mesial face is unarmed; P. antennarius has 19 or less (16-19 in the specimens examined) corneous spines on the ventral margins of the dactyls of the second and third pereopods, and the mesial faces of these dactyls have a row of small corneous spines on each second pereopod and a shorter row of small spines proximally on each third pereopod. Moreover, in addition to rows of setae near each dorsal and ventral margin of the mesial and lateral faces of propodi of the second and third pereopods, a row of long and dense setae is present medially in P. antennarius , while in P. miyakei this median row of setae is absent. The tubercles on the mesial faces of the dactyls of the chelipeds of P. antennarius are more or less arranged longitudinally in three rows: the first row is situated near the dorsal margin with each tubercle accompanied by tuft of setae, the second and third rows are irregular or scattered with one or two short setae; in P.miyakei the tubercles are arranged in oblique rows. Additionally, the telson in P.antennarius is remarkably asymmetrical, while in P. miyakei it is only slightly asymmetrical. The chelipeds and pereopods of P. antennarius also are covered with longer and denser setae than in P. miyakei . Although these two latter characters are variable, they are constant over the size range and sex of the specimens studied.

Paguristes lauriei McLaughlin & Hogarth, 1998 ( Fig. 1 )

Paguristes mundus – Laurie 1926: 154. Non Alcock, 1905.

Paguristes lauriei McLaughlin & Hogarth, 1998: 16 , figs 6-10.

MATERIAL EXAMINED. — Seychelles Island. Reves II Expedition, stn 1, 5°24.8’S, 57°03.5’E, 55 m, sand, 2.IX.1980, 1 ♀ (3.3 mm) ; 1 ovig. ♀ (4.9 mm). — Stn 5, 5°04.48’S,

56°23.8’E, 33 m, fine sand and shells, 4.IX.1980, 3 ♂♂ (2.4-6.4 mm); 8 ♀♀ (2.6-3.4 mm) ; 9 ovig. ♀♀ (3.9- 4.3 mm). — Stn 6, 4°57.8’S, 56°12.0’E, 40-45 m, sand with shells, 4.IX.1980, 2 ♀♀ (3.0 mm); 1 ovig. ♀ (3.6 mm). — Stn 11, 5°05.4’S, 55°54.4’E, 58 m, sand, 7.IX.1980, 1 ♂ (1.9 mm); 1 ♀ (3.4 mm). — Stn 15, 5°32.4’S, 56°43.9’E, 40-45 m, sand, 4.IX.1980, 1 ovig. ♀ (4.2 mm). — Stn 22, 5°16.3’S, 55°58.2’E, 60 m, sand and shells debris, 6.IX.1980, 1 ♂ (3.3 mm); 1 ovig. ♀ (4.3 mm). — Stn 23, 5°15.0’S, 55°42.2’E, 45-50 m, sand and shells debris, 7.IX.1980, 1 ♂ (3.4 mm). — Stn 31, 4°37.4’S, 54°20.7’E, 50 m, shells debris, 9.IX.1980, 1 ♂ (3.0 mm). — Stn 33, 5°25.9’S, 54°39.0’E, 45-60 m, sand and mud, 10.IX.1980, 1 ♂ (4.2 mm). — Stn 37, 4°35.8’S, 55°12.7’E, 65 m, sand and shell debris, 10.IX.1980, 3 ♂♂ (2.9-3.0 mm); 2 ovig. ♀♀ (3.2, 4.0 mm). — Stn 38, 5°03.5’S, 56°50.5’E, 44 m, mud and dead coral, 13.IX.1980, 1 ♂ (2.0 mm); 1 ♀ (4.4 mm) ; 2 ovig. ♀♀ (3.6 and 4.0 mm). — Stn 42, 4°31.6’S, 56°09.7’E, 55- 60 m, shells debris, 13.IX.1980, 1 ♂ (4.4 mm); 1 ovig. ♀ (4.8 mm). — Stn 46, 4°06.7’S, 56°10.6’E, 60 m, sandy mud, 14.IX.1980, 1 ♂ (4.2 mm). — Stn 47, 4°03.8’S, 55°59.5’E, 45-55 m, shells debris, 14.IX.1980, 1 ♀ (4.6 mm). — Stn 49, 3°54.7’S, 55°50.6’E, 57 m, sand and shells debris, 15.IX.1980, 1 ♂ (4.0 mm). — Stn 55, 3°48.0’S, 55°06.2’E, 50-55 m, shells debris, 17.IX.1980, 1 ♂ (3.6 mm). — Stn 61, 4°22.3’S, 55°22.0’E, 65 m, shells debris, 19.IX.1980, 1 ♂ (4.4 mm).

La Réunion. Marion Dufresne, MD 32, stn FA 40, 21°21’S, 55°27’E, 150 m, 18.VIII.1982, 1 ovig. ♀ (6.2 mm). — Stn DC 56, 21°05’S, 55°12’E, 170-225 m, 22.VIII.1982, 1 ♀ (3.4 mm).

DISTRIBUTION. — Seychelles and la Réunion in the western Indian Ocean, at depths from 40 to 225 m.

DESCRIPTION

Thirteen pairs of quadriserial gills. Shield almost 1.2 longer than broad, rostrum slender, acutely triangular, reaching proximal third of ocular acicles. Lateral projections shorter than rostrum. Ocular peduncles unequal, left slightly longer than right, longer than antennal and antennular peduncles. Ocular acicles subtriangular, terminating acutely. Antennal acicle reaching to distal fifth of fifth peduncular segment, terminating in prominent bifid spine; two spines on lateral margin, three or four spines on mesial margin and few setae. Antennal flagellum about 1.5 length of shield; articles each with one to two short setae.

Chelipeds subequal, left larger than right, armament similar. Left cheliped with dactyl 1.5 length of palm; dorsal surface of dactyl with two irregular rows of tuberculate spines and sparse short setae; mesial face ( Fig. 1A ) with irregular rows of tuberculate spines dorsally, each accompanied by one or two short setae, few tufts of setae near ventral margin. Palm with row of five prominent spines on dorsomesial margin, convex dorsal surface with rows of small to large tuberculate spines, rounded dorsolateral margin with row of tuberculate spines continued onto fixed finger, some spines accompanied by one or two setae. Carpus with row of five prominent spines on dorsomesial margin, each accompanied by sparse setae; dorsal surface with irregular rows of tuberculate spines, each also accompanied by one or two setae. Merus with row of prominent spines on distal margin extending onto lateral margin, dorsal surface with subdistal short, transverse row of spines also extending to lateral face, remainder of dorsal surface with row of corneous-tipped spines, becoming smaller proximally; ventromesial margin with row of prominent spines and sparse setae; ventrolateral margin with row of corneous-tipped spines and sparse setae. Ischium with several small spines on ventromesial margin.

Second and third pereopods ( Fig. 1 B-E) similar from left to right. Dactyls 1.5-1.6 length of propodi, dorsal margins of dactyls each with row of corneous-tipped spines, becoming smaller distally, accompanied by long stiff setae (second), with row of small corneous spines also accompanied by long, stiff setae (third); lateral faces each with rows of tuft of short, sparse setae, shallow longitudinal sulcus dorsoproximally; mesial faces each with longitudinal ridge, lower on second, accompanied by row of corneous spines, flanked by short proximal sulcus dorsally and long shallow sulcus ventrally, row of spinules on proximal half of ventral sulcus; ventral margins each with row of 16-19 corneous spines. Dorsal margins of propodi each with row of prominent corneous-tipped spines (second) or corneous-tipped protuberances (third), each accompanied by tufts of short setae, lateral surfaces each with shallow longitudinal sulcus medially, deeper median sulcus on third, and row of short, sparse setae; mesial faces of second each with scattered tubercles, denser proximally, two to four corneous spines ventrodistally; third smooth, one or two corneous spines ventrodistally, few tufts of sparse

C

setae; ventral margins each with row of spinules and setae (second) or with sparse setae (third). Dorsal margins of carpi each with row of prominent spines (second) or spinules (third) and sparse tufts of long setae; lateral faces each with longitudinal sulcus and sparse setae. Meri with ventromesial and ventrolateral margins of second each with row of small spines and long setae; third unarmed. Fourth pereopod ( Fig. 1F ) with preungual process at base of dactylar claw, no spine on distal margin of carpus.

Male first pleopods ( Fig. 1G, H ) each with single row of small hook-like corneous spines on distal margin of inferior lamella; external lobe slightly shorter than inferior lamella, internal lobe short, with marginal setae. Basal segments of second pleopods ( Fig. 1I ) glabrous, endopods slightly twisted, long setae on distal margins. Female gonopores paired; brood pouch ( Fig. 1J ) large, rounded, distal margin fringed with long setae. Pleon with longitudinal tergal thickenings covered by long plumose setae above acetabula of second and third pleopods. Eggs numerous, diameter about 0.7 mm.

Telson ( Fig. 1K ) with moderately deep lateral incisions; shallow and narrow median cleft; posterior lobes asymmetrical, terminal and lateral margins unarmed, each with row of long setae.

Colour in preservative

(after McLaughlin & Hogarth 1998)

Shield white with mottling of orange. Ocular peduncles solidly orange; ocular acicle mottled orange and white spines with reddish tips. Antennular peduncles with faint orange tint. Antennal peduncles with faintly tinted fifth, fourth and third segments; first and second segment and acicles mottled orange and white. Meri of chelipeds with faint orange tint, mesial and lateral faces each with circular patch of dark orange in distal third; carpi also with faint orange tint, some spines with slightly darker tint; chelae generally white with few spines orange-tinted, dactyls each with submedian orange band. Ambulatory legs with scattered splotches of orange on white background colour; mottled orange bands as follows: one submedian band on merus and propodus, two, one subproximal and one subdistal, on dactyl.

In the material studied, most of the coloration is still visible especially the dark orange circular patch on distal third of each mesial and lateral face of merus.

VARIATION

Variation appears to be size related. McLaughlin (in press) noted that the holotype of P. lauriei had unarmed mesial face dactyls of the chelipeds. In the small specimens examined in this study (shield length 1.9-4.0 mm) these surfaces are either unarmed or armed with a longitudinal row of low protuberance or tuberculate spines. In large specimens (> 4.5 mm) they have one or two irregular rows of tuberculate spines dorsally.

Most of the large specimens have unequal chelipeds, the right much smaller than left, but the armament is the same. In the largest specimen (SL 6.9 mm) the tuberculate spines on the dorsal surface of palm and fixed finger and the spines on the dorsomesial margin of palm are smaller and widely-spaced.

The mesial faces of the second and third pereopods of small specimens are slightly convex; each with only a proximal, shallow longitudinal sulcus dorsally rather than a ridge flanked by sulci dorsally and ventrally in large specimens. Additionally, the row of corneous spines on the mesial face of the dactyl in small specimens is on the proximal half of each second pereopod only, while in large specimens it is on the entire length of dactyl of each second and third pereopods.

REMARKS

The morphological characters and colour of the specimens examined during this study agree well with McLaughlin & Hogarth’s (1998) description of P. lauriei . McLaughlin & Hogarth described this species from a single female specimen lacking half of the pleon. They assumed that the brood pouch was missing as the eggs were shielded by a uniform row of long, dense, plumose setae arising dorsally from a thickened longitudinal tergal ridge that extended from anterior of the acetabulum of the second pleopod to just posterior of the third ( McLaughlin & Hogarth 1998: 20). The presence of female and male specimens in this study provides the opportunity to complete the description of this species. As mentioned by McLaughlin & Hogarth (1998) the thickened pleonal tergal ridges each are interrupted by a short membraneous space between the acetabula of the second and the third pleopods. In the females of this study, above the acetabulum of the fourth pleopod, the tergal ridge is also thickened, short, and separated from the third ridge by a moderately wide space and a large, rounded brood pouch situated adjacent to the fourth pleopod. The eggs are attached to the second, third and fourth pleopods, and only those on the fourth pleopod are protected by the brood pouch, whereas the eggs on the second and third pleopods are shielded by the long, dense, plumose setae.

Figures

FIG. 1. — Paguristes lauriei McLaughlin & Hogarth, 1998: A-I, K, ♂, 6.9 mm; J, ♀, 4 mm; A, dactyl of left cheliped, mesial face; B, left second pereopod,lateral view; C, same, mesial view;D, left third pereopod, lateral view;E, same,mesial view;F, left fourth pereopod, lateral view; G, male first pleopod, external view;H, same,internal view; I, male second pleopod,internal view; J, female brood pouch, external view; K, telson, dorsal view. Setae partially omitted. Scale bars: 1 mm.