Paguristes lewinsohni, Mclaughlin, Patsy A. & Rahayu, Dwi Listyo, 2005

Mclaughlin, Patsy A. & Rahayu, Dwi Listyo, 2005, Two new species of Paguristes sensu stricto (Decapoda: Anomura: Paguroidea: Diogenidae) and a review of Paguristes pusillus Henderson, Zootaxa 1083, pp. 37-62 : 49-55

Paguristes lewinsohni n. sp. ( Figs. 4 , 5 )

Paguristes sp. — Lewinsohn, 1969: 13, fig. 1.

Paguristes sp. a. — Morgan & Forest, 1991: 687.

Paguristes pusillus .— Thompson, 1943: 414 [Not Paguristes pusillus Henderson, 1896 ].

Type material. Red Sea: holotype male (5.3 mm), Dahlak Archipelago, stn 7, 15°32’N, 40°23’E, 110 m, 19 Oct 1965 ( TAU 1827). Paratypes Red Sea: Dahlak Archipelago, 1 male (shield damaged), stn 7, 15°32’N, 40°23’E, 110 m, 19 Oct 1965, TAU 1827; 1 male (3.4 mm), stn 9, 15°35’N, 40°40’E, 20–24 m, 22 Oct 1965, TAU 2465; 1 female (3.2 mm), stn 10, 15°37’N, 40°43’E, 27 m, 23 Oct 1965 TAU 2460; 1male (4.7 mm), stn 12, 15°35’N, 40°44’E, 36 m, 23 Oct 1965, TAU 1895; Southern Red Sea: 1 male (2.8 mm), coll. O.H. Oren, TAU E58/280. South Arabian coast: 2 males (3.3, 5.9 mm), 3 ovig. females (2.86.0mm), John Murray Expedition, stn 45, 18°03’30”N, 57°02’30”E, 38m, 29 Oct 1933, NMH 1952.6.17.20–25; Gulf of Oman: 1 ovig. female (5.4 mm), stn 72, 25°38’ 18”N, 56°26’36”E, 73m, 26 Nov 1933, NHM 1952.6.17.20–25.

Description. Thirteen pairs of quadriserial gills. Shield ( Fig. 4 a) slightly longer than broad; dorsal surface with few small spines or minute spinules marginally and/or laterally, several tufts of moderate to long setae. Lateral projections subtriangular, acute, each with tiny or small marginal spine terminally. Rostrum usually very slender, acute, reaching to or well beyond mid­length of ocular acicles, with tiny terminal spinule. Branchiostegites each with few moderately small spines on dorsal margin, at least distally.

Ocular peduncles moderately slender, somewhat unequal, left slightly longer, 0.6–0.8 length of shield; overreaching both antennular and antennal peduncles; dorsal surfaces each with few plumose setae; corneas 0.2 of peduncular length. Ocular acicles moderately slender, each with 2 or 3 small spines; separated by considerably more than basal width of rostrum.

Antennular peduncles when fully extended reaching to or slightly beyond basal margin of cornea of left ocular peduncle. Ultimate and penultimate segments with few short setae. Basal segment with small spine on dorsolateral surface.

Antennal peduncles reaching 0.5–0.7 length of left ocular peduncle. Fifth segment with few scattered, moderately long setae. Fourth segment with acute dorsodistal spine. Third segment prominently produced ventrally and terminating in simple spine. Second segment with produced dorsolateral distal angle terminating in bifid or occasionally weakly trifid spine; dorsomesial distal angle unarmed or with prominent spine; lateral and mesial margins each with several long setae and occasionally small accessory spine laterally. First segment unarmed. Antennal acicle reaching beyond proximal half of ultimate peduncular segment, with bifid terminal spine; mesial and lateral margins each with 1–4 spines, margins and dorsal surfaces all with numerous long, plumose setae. Antennal flagella varying from shorter than shield to approximately equaling length of carapace; each article with several short to moderately long setae.

Third maxilliped with 1 small subacute spine on ventral margin of basis; ischium with crista dentata composed on row of small teeth, 1 small spine on ventrodistal margin; dorsodistal margin of merus with small spine, ventral margin with 4 or 5 spines; carpus with 1 dorsodistal and often 1 ventrodistal spine or spinule.

Chelipeds unequal; left appreciably larger; armament of chelae somewhat dissimilar. Left cheliped ( Fig. 5 a) with propodal/carpal articulation rotated counterclockwise 15°–30° from horizontal. Dactyl 1.3–1.5 longer than palm, somewhat triangular in shape (in dorsal view); dorsomesial margin delimited by row of low, spinulose tubercles or small tuberculate, often corneous­tipped spines accompanied by few simple setae; dorsal surface varying from few small tubercles and scattered short setae to covering of relatively closely­packed spinulose tubercles; mesial face ( Fig. 5 b) with numerous small tubercles usually forming irregular rows and partially concealed by short setae; ventral surface with scattered setae; cutting edge with row of calcareous teeth in proximal 0.6–0.8, small, corneous teeth distally; terminating in very small corneous claw. Palm slightly shorter than carpus, dorsoventrally somewhat swollen, fixed finger somewhat compressed; dorsal surface with scattered tufts of moderately long, simple and plumose setae, densest marginally, and with covering of moderately closely­set, small, often corneous­tipped, tuberculate spines or spinulose tubercles, each accompanied by short setae, dorsomesial margin only weakly delimited by row of similar, only slightly larger spines; mesial face with scattered small spines or spinulose tubercles and tufts of plumose setae; dorsolateral margin not distinctly delimited but with fringe of long plumose setae, extending to tip of fixed finger and partially concealing marginal spination; ventral surface with low, often spinulose protuberances and sparse tufts of plumose setae; cutting edge of fixed finger with row of small calcareous teeth, terminating in small corneous claw. Carpus approximately half length of merus; dorsomesial margin with row of small spines, dorsal surface with covering of similar, frequently corneous­tipped spines or spinulose tubercles accompanied by short setae, dorsolateral margin not delimited; lateral face with few spinules; mesial face with numerous small spines, including row on distal margin; all surfaces with plumose setae. Merus acutely triangular; dorsodistal and laterodistal margins with row of well developed spines, dorsal margin with subdistal transverse spinose ridge, remainder of margin spinose; lateral face weakly spinulose, ventrolateral margin with row of small spines; mesial face usually glabrous, ventromesial margin with row of subacute spines; margins, and ventral surface particularly, with abundance of long plumose setae. Ischium with row of spinules on ventromesial margin, obscured by long, plumose setae.

Right cheliped ( Fig. 5 c) appreciably narrower than left and with approximately 30° clockwise propodal/carpal rotation from horizontal. Dactyl 0.7 to twice length of palm; dorsomesial margin with row of corneous­tipped spines, not concealed by accompanying setae; dorsal surface with 3 or 4 irregular rows of small, often corneous­tipped spines and short setae; mesial face ( Fig. 5 d) with longitudinal row of small spinulose tubercles dorsally accompanied and partially concealed by tufts of moderately short setae, 1 or 2 irregular rows of low protuberances ventrally; ventral surface with few tufts of long setae; cutting edge with row of small calcareous teeth in proximal 0.5–0.7, corneous teeth distally; terminating in small corneous claw. Palm 0.6–0.8 length of carpus; dorsomesial margin with row of 5 or occasionally 6 prominent, corneous­tipped spines and tufts of long, plumose setae, dorsal surface with scattered tufts of moderately long, plumose setae and with covering of moderately widely­spaced, somewhat tuberculate, frequently corneous­tipped spines, each usually accompanied by short setae, dorsolateral margin angular but not distinctly delimited; cutting edge of fixed finger with row of small calcareous teeth, terminating in small corneous claw; ventral surfaces of palm and fixed finger with numerous spinose protuberances or tubercles and scattered tufts of long setae. Carpus with 5–7 large, corneous­tipped, conical spines on dorsomesial margin and 1 or 2 moderately prominent, corneous­tipped spines on proximal margin, all accompanied by tufts of long, plumose setae; dorsal surface with scattered tufts of moderately long, plumose setae and with covering of moderately closely­set, but not packed, small, sometimes corneous­tipped spines, each usually accompanied by short setae, dorsolateral margin angular; lateral face with scattered small spines. Merus subtriangular; dorsal margin with numerous long setae, row of moderately small, corneous­tipped spines on dorsodistal and dorsolateral margins, dorsomesial margin with much smaller spinules; 1 short, transverse row of simple, bifid or multifid spines subdistally, and longitudinal row of much smaller spines proximally on dorsal margin; lateral surface with scattered simple and bifid small spines and spinules, ventrolateral margin spinulose; mesial face with only few scattered spinules, ventromesial margin with row of small spines or spinules; ventral surface with scattered small spines partially obscured by tufts of long, plumose setae. Ischium with row of spinules on ventromesial margin and tufts of long setae.

Ambulatory legs ( Fig. 5 e–h) with dactyls of second pereopods shorter and broader than third. Dactyls 1.2–1.6 length of propodi; dorsal margins each with row of small or moderately small, often corneous­tipped spines on second pereopods, spinules or spinulose protuberances on third, all partially concealed by long setae; ventral margins each with row of 14–20 corneous spines, decreasing in size proximally, concealed by long, plumose setae, second pereopods each also with additional row of calcified, corneoustipped spines; mesial faces of second flattened or weakly concave, third weakly convex; each with numerous spinules or small spines, largest on second pereopods; lateral faces each with 2 or 3 rows of tufts of short setae on second pereopods, third with very few sparse tufts. Propodi each with single or double row of conical, corneous­tipped spines and long, plumose setae on dorsal margin of second, third minutely spinulose; mesial faces spinulose, with spinulose, scute­like ridges frequently developed ventrally on second pereopods; lateral surfaces unarmed but often with few sparse tufts of setae; ventral surfaces of second each with row of spines, third weakly spinulose. Carpi of second pereopods each with irregular double row of prominent, often corneous­tipped spines on dorsal surface distally, frequently displaced onto mesial face in proximal half and accompanied by tufts of long setae; third pereopods each with prominent dorsodistal spine and row of low protuberances or tiny spines and spinules on dorsal surface; lateral faces sometimes minutely to distinctly spinulose and with scattered tufts of shorter setae, each also with shallow, longitudinal sulcus. Meri each with row of small spines or spinulose protuberances dorsally on second pereopods, ventral margins each with single or double row of spines, third pereopods unarmed or with few low protuberances; all with dorsal and ventral long setae. Ischia of second pereopods each frequently with few small spines on dorsal margin; third unarmed. Dactyls of fourth pereopods each with prominent preungual process at base of claw.

Male first gonopods ( Fig. 4 b, c) each with tuft of long setae on mesial margin of proximal segment proximally; inferior lamella with row moderately long setae on outer margin, row of closely­spaced small hooked spines on distal margin; external lobe only very slightly longer than distal margin of inferior lamella; internal lobe approximately half length of external lobe, with long setae on margin and inferior face. Male second gonopods ( Fig. 4 d) with naked basal segment; endopod with row of marginal long setae and terminal tuft of setae; appendix masculina with marginal long setae. Females with paired gonopores; paired first pleopods 2­segmented, distal segment with long setae; brood pouch large, very thin, with margin weakly scalloped.

Telson ( Fig. 4 e) with prominent lateral indentations; posterior lobes subtriangular, asymmetrical, with left somewhat to appreciably longer; terminal margins unarmed but each with row of long, simple setae; median cleft weakly developed or absent.

Color. In preservative, Lewinsohn (1969: 15) reported that a large red patch was present on each mesial and lateral face of the meri of the chelipeds.

Habitat. Gastropod shells overgrown with unidentified sponge.

Distribution. Dahlak Archipelago and southern Red Sea; Arabian coast; Gulf of Oman; 18– 110 m.

Etymology. This species is dedicated to the late Chanan Lewinsohn, who provided the first description and illustrations.

Variation. The small male from the southern Red Sea differs from the holotype and other Dahlak paratypes in having a noticeably shorter rostrum, more acute spines on the dorsal surfaces of the chelae and more prominent, almost pear­shaped spines on the dorsal margins of the propodi of the second pereopods. It is not uncommon for rostral length to increase with increasing animal size, whereas the acuteness of the spines frequently decreases with increasing size, particularly in males. Similarly, the spines of the chelipeds and ambulatory legs of the small females from the Arabian coast are more numerous and acute. These variations correlate with the appreciably smaller sizes of these specimens and are believed to reflect allometry.

Some variation in the armatures of the mesial faces of the dactyls of the right and left chelipeds was present. The left dactyl most commonly had one or two quasi regular rows of spines dorsally and numerous tuberculate protuberances forming irregular rows in the ventral half of the surface. In contrast, the mesial face of the right dactyl usually had only a single dorsal row of spines or spinulose tubercles and fewer tubercles or setal protuberances on lower half of the surface. The number and density of the tubercles on the left dactyl appeared to increase with increasing animal size, but that was not the case for the right.

Remarks. As previously indicated, although reported in his 1969 publication as Paguristes sp., Lewinsohn subsequently concluded that the specimens from the Dahlak Archipelago were identifiable as Paguristes ciliatus sensu Alcock (1905) , whereas the male from the southern Red Sea (E58/280) represented P. pusillus . Some of the Dahlak specimens are now missing from the Tel­Aviv Museum collections (Alex Shlagman, pers. comm.), with the specimens listed above under Material examined being all that could be located. Lewinsohn’s specimen from E58/280 is not much smaller than Henderson’s specimen of P. p u s i l l u s, and the relative short rostra and acuteness of the spination of the chelipeds and ambulatory legs are similar. This may have led Lewinsohn to believe that his southern Red Sea specimen was conspecific with P. p u s i l l u s. However, the two species are immediately distinguished by two important characters: 1) the chelipeds of the small Red Sea male are unequal and dissimilar as they are in the Dahlak and Arabian specimens; the chelipeds of P. pusillus are subequal and similar; 2) the armature of the mesial face of the dactyl of the left cheliped in Lewinsohn’s specimen has the somewhat irregular rows of spinules and tubercles characteristic of P. lewinsohni n. sp., whereas there is a single row of moderately large tuberculate spines in P. pusillus .

Figures

FIGURE 4. Paguristes lewinsohni n. sp., Dahlak Archipelago, stn 7: a, e, holotype male (5.3 mm) (TAU 1827); b – d, male paratype (shield damaged) (TAU 1827). a, shield and cephalic appendages (aesthetascs and setae omitted); b, left first pleopod (external view); c, left first pleopod (internal view); d, left second pleopod (external view); e, telson (setae omitted). Scales equal 1 mm.

FIGURE 5. Paguristes lewinsohni n. sp., Dahlak Archipelago, stn 7, male paratype (shield damaged) (TAU 1827). a, chela and carpus of left cheliped (dorsal view; setae omitted); b, dactyl of left chela (mesial view, setae omitted); c, chela and carpus of right cheliped (dorsal view, setae omitted); d, dactyl of right chela (mesial view, setae omitted); e, right second pereopod (lateral view); f, dactyl, propodus and carpus of right second pereopod (mesial view, setae omitted); g, left third pereopod (lateral view); h, dactyl and propodus of left third pereopod (mesial view, setae omitted). Scales equal 2 mm.