Pagurus fungiformis, Komai & Rahayu, 2004

Komai, Tomoyuki & Rahayu, Dwi Listyo, 2004, Redescription Of Pagurus Moluccensis Haig & Ball, 1988, With Description Of A New Species Of Pagurus From Indonesia, And Taxonomic Notes On The Pagurus Anachoretus Group (Crustacea: Decapoda: Anomura: Paguridae), Raffles Bulletin of Zoology 52 (1), pp. 183-200 : 191-198

Pagurus fungiformis , new species

( Figs. 1B , 6-9 )

Material examined. – Holotype - male (sl 3.6 mm) ( MZB Cru 1506), Bitung , Sulawesi, intertidal, 26 Jul.1996.

Paratypes - 1 female (sl 2.1 mm) ( MZB), same data as for holotype ; 1 male (sl 2.7 mm), 1 female (sl 1.9 mm) ( CBM-ZC 5572 ), Tanawanako , north of Sulawesi, intertidal, 23 Dec.1997 ; 1 male (sl 2.5 mm) ( ZRC 2002.0518 ), same data ; 3 males (sl 1.4-1.9 mm), 3 ovigerous females (sl 2.1- 2.1 mm) ( MZB Cru 1507), Tial, Ambon Island, intertidal, 28 Feb.1998 ; 1 male (sl 2.0 mm), 2 ovigerous females (sl 2.1, 2.1 mm) (MNHN-Pg 6343), same data .

Description. – Eleven pairs of biserial phyllobranchiae; 2 well-developed arthrobranchs on third maxilliped. Calcified integument of carapace and thoracic appendages with small blister-like tubercles ( Figs. 6A, B, H, K , 9A, C, E, G ).

Shield ( Fig. 6A ) 1.0-1.1 times as long as broad; anterior margin between rostrum and lateral projections weakly concave; anterolateral margins sloping; posterior margin roundly truncate; rostrum broadly rounded, slightly overreaching lateral projections; lateral projections obsolete, without marginal or submarginal spine; dorsal surface with some tufts of short setae laterally; paragastric grooves conspicuous. Posterior carapace similar to that of P. moluccensis .

Ocular peduncles ( Fig. 6A ) 0.7-0.8 times as long as shield, moderately stout (about 3.5 times longer than width of cornea), slightly inflated basally; corneas not dilated; dorsal surface with row of tufts of short setae mesially. Ocular acicles ( Fig. 6B ) subovate, each with small marginal spine. Interocular lobe ( Fig. 6B ) with elongate 2 processes, each terminating acutely and reaching nearly distal margins of ocular acicles.

Antennular peduncles ( Fig. 6A ), when fully extended, reaching distal margins of corneas. Ultimate segment moderately stout, about 1.9 times longer than penultimate segment, increasing in depth distally, with few tufts of short setae on dorsal surfaces. Basal segment devoid of distolateral lobe; statocyst-bearing lobe unarmed.

Antennal peduncles ( Fig. 6A ) overreaching distal margins of corneas by 0.1-0.2 length of fifth segment. Fifth and fourth segments with few very short setae. Third segment unarmed on ventromesial distal angle, mesial face with short setae. Second segment with dorsolateral distal angle produced, not reaching midlength of fourth segment, terminating in small spine; dorsomesial distal angle unarmed; mesial margin with setae. Basal segment with small spine on lateral face; ventrodistal margin with 3 spinules just laterad of antennal gland opening. Antennal acicle slightly overreaching distal margin of fourth segment, somewhat arcuate, terminating in small spine, with sparse moderately short setae on mesial margin. Antennal flagella moderately long, each article with very short setae on distal margin.

Mouthparts generally similar to those of P. moluccensis ( Figs. 6 C-E). Maxillule ( Fig. 6C ) with 1 apical bristle on distinctly produced internal lobe of endopod; external lobe of endopod rounded, basally articulated. Third maxilliped ( Fig. 6F ) with crista dentata on ischium ( Fig. 6G ) composed of row of small corneous spines increasing in size distally; 2 unequal accessory teeth on ischium; merus unarmed on dorsodistal or ventromesial margin; carpus unarmed on dorsodistal margin; exopod reaching midlength of carpus.

Right cheliped ( Figs. 7 A-E) appreciably larger than left. Right chela 1.6-1.7 times longer than greatest width at base of dactylus. Dactylus 0.8-0.9 times as long as palm, somewhat curved ventrally; dorsal and mesial surfaces covered with closely set, flattened, rounded tubercles (often marginally denticulate); dorsomesial margin not delimited in males ( Fig. 7A ), distinctly delimited by row of small spines in females ( Fig. 7E ); ventromesial margin delimited by row of flattened tubercles, proximal tubercles distally denticulate, distal tubercles simple or bifid; ventral surface unarmed, with 3 rows of tufts of short setae; cutting edge with row of small calcareous teeth (blunt in males, blunt to acute in females) in proximal 0.7-0.8 and row of small corneous teeth in distal 0.2-0.3, terminating in small corneous claw. Palm slightly shorter than carpus; dorsal surface convex (degree of convexity weaker in females than in males), covered with closely set, flattened, marginally denticulate tubercles and few short setae (tubercles occasionally poorly developed in females; see Fig. 7E ); in females, shallow longitudinal sulcus present adjacent to dorsomesial border ( Fig. 7E ); dorsolateral margin of palm proper not delimited, that of fixed finger only slightly delimited by row of small tubercles in males ( Figs. 7A, C ), distinctly delimited by row of small spines in females ( Fig. 7E ); dorsomesial margin not delimited; lateral face with scattered low, simple or denticulate tubercles; mesial face with numerous small tubercles (tubercles spaced, distally bifid or multifid); ventral surface weakly convex, with scattered low, distally denticulate tubercles and short setae. In males, cutting edge of fixed finger in males with row of blunt calcareous teeth, terminating in minute corneous claw; in females, cutting edge of fixed finger with row of blunt to acute calcareous teeth (distal teeth interspersed by short rows of small corneous teeth), terminating in small corneous claw. Carpus slightly shorter to slightly longer than merus, noticeably broadened distally in dorsal view; dorsal surface with small, bifid or denticulate tubercles laterally and mesially and few short setae, median part unarmed, dorsodistal margin with small tubercles or spines; dorsomesial margin delimited by single or double row of bifid or denticulate tubercles, dorsolateral margin not delimited; lateral face with scattered low, bifid tubercles or denticulate short ridges and few short setae, ventrolateral margin with short row of small spines distally; mesial surface flat, with small bifid or trifid tubercles and short setae adjacent to dorsomesial margin and scattered tiny tubercles, ventromesial margin with row of small, closely set spines; ventral surface weakly convex, with small to moderately large, low protuberances and short setae. Merus with low, occasionally denticulate protuberances on dorsal surface distally, dorsodistal margin unarmed, but with short setae; lateral face with scattered low, blister-like tubercles and few very short setae, ventrolateral margin with row of protuberances; mesial face only with few, short setae, ventromesial margin slightly crested, with row of small spines or denticulate tubercles; ventral surface somewhat concave, with row of low protuberances medially and scattered short setae. Ischium with tiny denticles on ventromesial margin; ventral surface with small blister-like tubercles and tufts of short setae. Coxa with blister-like tubercles or low protuberances.

Left cheliped ( Figs. 8 A-C) somewhat compressed laterally, reaching base to midlength of dactylus of right cheliped; propodal-carpal articulation about 15-20 from horizontal plane. Chela 2.2-2.3 times longer than wide. Dactylus about twice length of palm, slightly curved ventrally; dorsal surface with irregular double row of moderately small, distally denticulate tubercles and short setae on midline and single row of tiny tubercles mesiad of midline; dorsolateral margin not delimited; mesial face with 2 irregular rows of small, low tubercles or protuberances and tufts of short setae; ventral surface with 2 rows of tufts of short setae; cutting edge with row of small, acute calcareous teeth in proximal half and row of small corneous teeth in distal half, terminating in large corneous claw. Palm about half length of carpus; dorsal surface (including fixed finger) strongly oblique, with numerous denticulate tubercles; dorsolateral margin not delimited; dorsomesial part somewhat elevated, with small denticulate or simple tubercles and few short setae; ventrolateral margin of fixed finger delimited by row of denticulate tubercles; ventral surface (including fixed finger) with few low, distally denticulate protuberances and tufts of short to long setae. Cutting edge of fixed finger with row of small, acute or subacute calcareous teeth in proximal 0.6 and row of small corneous teeth in distal 0.4, terminating in large corneous claw. Carpus shorter than merus, widened distally in dorsal view; dorsal surface strongly oblique, with several low, denticulate protuberances laterally, dorsodistal margin with row of spines increasing in size laterally; dorsomesial margin with row of small spines or distally denticulate tubercles decreasing in size proximally and short setae; mesial face with few low protuberances or short denticulate ridges dorsally, nearly smooth ventrally; lateral face with scattered, short denticulate ridges, ventromesial margin with row of small spines distally; ventral surface convex, with few low protuberances and tufts of setae. Merus with dorsal surface almost smooth, bearing few short setae; dorsodistal margin unarmed; lateral face with scattered blister-like tubercles, ventrolateral margin with row of small spines on distal half; mesial face with few tiny tubercles dorsally and with long setae ventrally, ventromesial margin with row of moderately small spines; ventral surface weakly concave, with few small spines and numerous tufts of long setae. Ischium with few spinules on ventromesial margin; all surfaces with sparse short setae. Coxa similar to that of right.

Second and third pereopods ( Figs. 9A, C ) not overreaching right cheliped, generally similar from right to left in second, greatly dissimilar in setation in third. Dactyli approximately as long as propodi, slightly curved ventrally in lateral view and nearly straight in dorsal view, terminating in large corneous claws; dorsal surfaces each with sparse row of tufts of setae (second and right third) or with row of long setae (left third); lateral faces each with few tufts of short setae (second and right third) or with numerous long setae (left third); mesial faces ( Figs. 9B, D ) unarmed, with rows of tufts of short setae dorsally and ventrally; no median sulcus on lateral or mesial faces; ventral margins each with 5-7 moderately small corneous spines. Propodi longer than carpi, slightly curved ventrally (second and right third) or straight (left third), dorsal surfaces unarmed, but row of tufts of short setae (second and right third) or with row of short transverse rows of long setae occasionally extending onto lateral face (left third); lateral faces with few tufts of short setae (second and right third) or with tufts of long setae dorsally and ventrodistally (left third) and occasionally with small blisterlike tubercles; ventral surfaces each with 3-6 corneous spinules and few short setae (second and right third) or with row of tufts of long setae, giving brush-like structure (in left third). Carpi each with small dorsodistal spine; dorsal surfaces each with row of tufts of setae (setae longer in left third than in other pereopods); lateral faces convex, with small blisterlike tubercles and row of sparse tufts of short to moderately short setae dorsally and (setae more numerous in left third than in other pereopods); ventral surfaces each with few short setae (second and right third) or row of tufts of long setae (left third). Meri each with row of moderately long setae on dorsal and ventral margins; lateral faces with small blisterlike tubercles and few tufts of short setae; ventral margins each with tufts of short to long setae, ventrolateral distal margins slightly concave, unarmed. Ischia with short setae on dorsal and ventral surfaces. Coxae with large blister-like protuberances. In females moderately large, paired gonopores present on third pereopods.

Fourth pereopods ( Figs. 9E, G ) semichelate, markedly unequal with left larger than right. Dactyli broad, slightly curved or nearly straight, terminating in small, curved corneous claws; dorsal margins convex, each with row of tufts of short setae; ventral margins each with row of tiny, blunt corneous teeth; rounded, naked preungual process arising from ventral margin between claw and row of corneous teeth. Propodi each with long setae on dorsal surfaces; mesial face of left divided in two sections by slightly elevated median line bordered by row of long setae in left ( Fig. 9F ); mesial face of right flat, with few tufts of long setae ventrally ( Fig. 9H ); ventral margins convex, each with rasp composed of single row of small corneous scales. Carpi and meri each with moderately long to long setae on dorsal surface (setae more numerous in left than in right); mesial faces of carpi ventrally with row of long setae in left, without long setae in right.

Fifth pereopods in males with paired gonopores partially masked by tufts of short setae ( Fig. 6J ).

Anterior lobe of sixth thoracic sternite ( Figs. 6H, I ) broadly semicircular, skewed to left; posterior lobe broader than anterior lobe. Seventh and eighth thoracic sternite similar to those of P. moluccensis .

Telson ( Fig. 6K ) with distinct transverse indentations; posterior lobes slightly unequal, separated by moderately broad, deep median cleft; terminal margins weakly convex or nearly straight, each with 5-8 spines interspersed by spinules.

Coloration in life. – Color in general white with black or dark brown markings ( Fig. 1B ). Shield with black markings centrally; posterior carapace tinged with light brown. Ocular peduncles each with dark brown band proximal to midlength and brown spot just proximal to base of cornea on ventral surface. Interocular lobe black or dark brown. Antennular peduncles generally white, ultimate and penultimate segments each with band distally; basal segment with proximal band. Palms of chelipeds entirely white or with black blotches on dorsal surfaces; carpi and meri each with irregular transverse band. Dactyli of second and third pereopods with subdistal and subproximal black bands; propodi each with distal blotch and broad subproximal black band; carpi with broad black band and dorsodistal blotch; meri each with irregular markings on lateral face.

Distribution. – Known only from Sulawesi; shallow water of coral reefs.

Habitat. – Occupying a variety of gastropod shells.

Etymology. – The species is named for the Latin fungiformis (= mushroom-like shaped), in reference to the mushroomlike tubercles on the palms of the chelipeds.

Variations. – As is apparent from the description, this new species exhibits a considerable variation in the armature of the right cheliped.

Remarks. – As mentioned before, P. moluccensis and P. fungiformis , new species are distinctive in the genus Pagurus in having two-spined interocular lobe in the genus Pagurus . In other species of Pagurus , the interocular lobe is never twospined as such, although the anterior surface of the interocular lobe is slightly convex or slightly concave (except for P. decimbranchiae , see above). Similarly a two-spined interocular lobe has been reported only in two species of Anapagurus (see Garcia-Gomez, 1994). The basally articulated external lobe on the endopod of the maxillule found in P. moluccensis and P. fungiformis , new species may be also unusual for the genus, as the external lobe is not basally articulated usually in species of Pagurus (personal observation). In addition, the new species and P. moluccensis are strikingly similar in coloration in life. Recent studies have demonstrated that the coloration in life is often very useful for discrimination of closely related or sibling species of decapod crustaceans (Knowlton & Mills, 1992). The two species demonstrate that preliminary identifications based only on color may lead to errors. In spite of the suggested close relationship, there are a number of morphological differences between P. fungiformis , new species, and P. moluccensis . In the new species, the dactyli and palms of the chelipeds are provided with closely set, flattened, often marginally denticulate tubercles, instead of widely spaced, simple or bifid tubercles in P. moluccensis . The dorsolateral and dorsomesial margins of the palms of the chelipeds are not delineated in the new species, while those margins are clearly delimited with a row of small spines in P. moluccensis . The dorsomesial margin of the carpus of the right cheliped bears a row of multifid spines or denticulate protuberances in P. fungiformis , new species, in contrast to having a row of large spines in P. moluccensis . The left cheliped has a rotation of propodal-carpal articulation greater than 15 from the horizontal plane in the new species, while the propodalcarpal articulation of the right cheliped is not rotated in P. moluccensis . The interocular lobe is more elongate in P. fungiformis , new species, than in P. moluccensis ; further, each distal prolongation terminates acutely in P. fungiformis , new species, rather than bluntly in P. moluccensis . The left third pereopod is provided with brush-like, thick long setae mainly on the ventral surface of the dactylus and propodus in P. fungiformis , new species, which are absent in P. moluccensis . Pagurus fungiformis , new species and P. moluccensis are assignable to the Pagurus anachoretus group (cf. Forest, 1978), as they generally fit the definition of the species group (Forest & Ngoc-Ho, 1992; McLaughlin & Forest, 1999). This species group, named for its first member, Pagurus anachoretus ( Risso, 1827) from the Mediterranean, includes P. anachoretoides Forest, 1966 , P. gordonae ( Forest, 1956) , P. laurentae Forest, 1978 and P. souriei ( Forest, 1952) from the tropical eastern Atlantic, P. liochele ( Barnard, 1947) and P. emmersoni McLaughlin & Forest, 1999 from South Africa, and the Indo-West Pacific P. kulkarnii Sankolli, 1961 , and P. hedleyi (Grant & McCulloch, 1906) (see Forest, 1978; Forest & Ngoc-Ho, 1992; McLaughlin & Forest, 1999). Four other species from the tropical eastern Atlantic, P. alcocki ( Balss, 1911) , P. dartevelei ( Forest, 1952) , P. fimbriatus Forest, 1956 , and P. triangularis (Chevreaux & Bouvier, 1892) , also fitted the definition of the P. anachoretus group with the exception of the cheliped form (Forest & Ngoc-Ho, 1992; McLaughlin & Forest, 1999). Komai & Osawa (2001) suggested the possible affinities among P. decimbranchiae Komai & Osawa, 2001 , P. boriaustraliensis Morgan, 1990 , P. moluccensis , P. pitagsaleei McLaughlin, 2002 (as Pagurus sp. cf. boriaustraliensis ). McLaughlin (2002) compared P. pitagsaleei with P. boriaustraliensis , P. hedleyi and P. kulkarnii , although she did not make formal assignment of P. pitagsaleei and P. boriaustraliensis to the P. anachoretus group. During this study, we attempted to make a preliminary assessment of the affinities among the two species treated in this study and species of the P. anachoretus group. Seven species heretofore assigned to the P. anachoretus group and three of the four related species from the tropical eastern Atlantic have been examined during this study (see Appendix).

Although the group was well defined by the previous authors (Forest & Ngoc-Ho, 1992; McLaughlin & Forest, 1999), two supplemental characters may be added, i.e. the presence of low, blister-like tubercles on the calcified integuments of the body and pereopods and the widely separated anterolateral lobes on the eighth thoracic sternite, as the species of the P. anachoretus group examined here all have these characters. It is remarkable that the characters are shared also by P. dartevelei , P. fimbriatus and P. triangularis . The blister-like tubercles or protuberances on the calcified integuments are very low, and not easy to recognize without staining, and therefore, have been overlooked by previous authors. Specimens used by the senior author during the taxonomic studies of Pagurus in the northwestern Pacific ( Komai, 1993, 1994a, b, 1996, 1997, 1998, 1999, 2000a, b, 2003a, b; Komai & Imafuku, 1996; Komai & Mishima, 2003; Komai & Yu, 1999) have been routinely stained with methylene blue for observation. So far, the presence of the blister-like tubercles or protuberances is known only in species formally assigned to the P. anachoretus group and allied species.

Observations have been made also for other characters not fully mentioned by previous authors, such as the development of the paragastric grooves on the shield and the structure of the fourth pereopods. These characters were used by Komai & Osawa (2001) in suggesting the affinities among P. moluccensis , P. decimbranchiae , P. boriaustraliensis and P. pitagsaleei . It has been found that the two characters vary interspecifically among the species examined. It is interesting to note that the paragastric grooves on the shield are inconspicuous in the eight Eastern Atlantic species, but conspicuous in the two Indo-West Pacific species, P. hedleyi and P. kulkarnii . The degree of asymmetry of the fourth pereopods has been found to be variable among the 10 species of the P. anachoretus group personally examined during this study. In P. anachoretus , P. dartevellei and P. triangularis , the fourth pereopods are entirely similar between right and left, although either only male or only female specimen(s) have been available for these three species. In P. anachoretoides , P. fimbriatus and P. souriei , the asymmetry of the fourth pereopods appears variable between male and female; in males, the fourth pereopods are similar, but in females, the left pereopod is slightly to somewhat longer than the right and the mesial face of the left propodus bears a median row of long setae. In P. gordonae , P. hedleyi , P. kulkarnii and P. laurentae , the asymmetry of the fourth pereopods is most obvious, occurring in both sexes, as in P. moluccensis and P. fungiformis , new species. These two characters seem to be useful in assessing the relationships among species in the P. anachoretus group.

Our comparison supports the assumption that P. moluccensis , P. fungiformis , new species, the species heretofore assigned to P. anachoretus group, P. dartevellei , P. fimrbriatus and P. triangularis form a homogenous assemblage within heterogeneous Pagurus . Furthermore, it is suggested that P. moluccensis and the new species are closely related to P. hedleyi and P. kulkarnii . These four species share the following set of characters: the conspicuous paragastric grooves on the shield; the markedly unequal fourth pereopods in both male and female; the more or less rounded dorsal surface of the palm of the right chela with more or less convex, symmetrical mesial and lateral margins.

It is interesting to note that P. decimbranchiae also fits generally with the definition of P. anachoretus group and even has the set of the characters shared by P. moluccensis , P. fungiformis , new species, P. hedleyi and P. kulkarnii . The distinctly bilobed interocular lobe of P. decimbranchiae is also indicative the close relationship of the species to P. moluccensis and P. fungiformis . The characteristic of P. decimbranchiae is the greatly reduced arthrobranch above the third maxilliped represented only by a single rudimentary bud. However, it can be assumed that this character is presumably autapomorphic for the species, although the number of the gills has been used as a generic character in the paguroid systematics (e.g. McLaughlin, 1997). Therefore, we formally assign P. decimbranchiae to the P. anachoretus group.

McLaughlin & Forest (1999) suggested that the strong winglike projection of the ventromesial margin of the carpus and merus of the right cheliped, especially well-developed in the large males, is one of the characteristics of the anachoretus group. However, they clearly mentioned in the original description of P. emmersoni that the ventromesial margins of the carpus and merus of the right cheliped are not produced into wing-like projections in that species. Furthermore, no development of the wing-like projection on the right cheliped is seen in P. anachoretoides , P. anachoretus , P. gordonae , P. laurentae and P. souriei , as well as P. moluccensis , P. fungiformis , new species, and P. decimbranchiae . Therefore, this character is not useful for defining the P. anachoretus group.

Figures

Fig. 1. A, Pagurus moluccensis Haig & Ball, 1988, live male from Marsegu Island; B, Pagurus fungiformis, new species, live male from Marsegu Island.

Fig. 6. Pagurus fungiformis, new species. Holotype male from Bitung, Sulawesi (sl 3.6 mm; MZB Cru 1506). A, shield and cephalic appendages, dorsal (setae omitted on left); B, ocular acicles and interocular lobe, dorsal; C, maxillule, ventral (coxal endite broken off); inset, endopod, lateral; D, left maxilla, ventral (setae omitted); E, left second maxilliped, ventral; F, left third maxilliped, lateral; G, ischium of left third maxilliped, dorsal; H, coxae of first to third pereopod and fifth and sixth thoracic sternites, ventral; I, anterior lobe of sixth thoracic sternite, ventral; J, coxae of fifth pereopods and eighth thoracic sternite, ventral; K, telson, dorsal.

Fig. 7. Pagurus fungiformis, new species. A-D, holotype male from Bitung, Sulawesi (sl 3.6 mm; MZB Cru 1506); E, paratype female from same locality (sl 2.1 mm; MZB Cru 1507). Right cheliped. A, E, chela, dorsal (setae omitted); B, entire cheliped, mesial; C, same, lateral; D, carpus, dorsal.

Fig. 9. Pagurus fungiformis, new species. A-D, holotype male sl 3.6 mm from Bitung, Sulawesi (sl 3.6 mm; MZB Cru 1506); E-H, female paratype from same locality (sl 2.1 mm; MZB Cru 1507). A, right second pereopod, lateral; B, dactylus of right second pereopod, mesial; C, left third pereopod, lateral; D, dactylus of left third pereopod, mesial; E, left fourth pereopod, lateral; F, dactylus and propodus of left fourth pereopod, medial; G, right fourth pereopod, lateral; H, dactylus and propodus of right fourth pereopod, mesial.