CRUSTACEAN RESEARCH, NO. 22 : 11-20. 1993 A new genus of Parapaguridae (Decapoda: Anomura) Rafael Lemaitre Abstract. — A new monotypic genus, removed from Sympagurus and placed in Bivalvopagurus, is described for Bivalvopagurus, new genus. The new genus Sympagurus sinensis (de Saint Laurent), a is diagnosed and its only species redescribed species of Parapaguridae known so far and illustrated. only from the China Sea. The new genus The material used for this study remains is distinguished from other genera in the deposited in the Museum national d'Hist- family by the presence of paired pleopods oire naiurelle. Paris (MNHN), and at the in both sexes, calcification of the shield, National Museum of Natural History, posterior carapace, and tcrgites of the Smithsonian Institution, Washington, D. C. first two abdominal somites, and symmetry (USNM). The following abbreviations are of the uropods and telson. The only species used: SL. length of shield (to the nearest in the new genus commonly uses a bivalve 0.1 mm), measured from the tip of the ros- shell with an actinian as means of par- trum to the midpoint of the posterior mar- tially protecting its abdomen. This species gin of the shield; and MUSORSTOM, expe- is redescribed and illustrated, and some dition of the MNHN and the office de la evolutionary comments are made. Recherche Scientifique et Technique Outre- Mer. Introduction Systematic Account Among the species assigned by Lemaitre F'amily Parapaguridae Smith, 1882 (1989: 37) to the heterogeneous genus Bivalvopagurus new genus Sympagurus Smith, 1883, was Parapagurus sinensis. a species briefly described by de Diagnosis. Shield distinctly broader Saint Laurent (1972) based on two speci- than long, well calcified. Eyestalks stout. mens from the China Sea. The assignment Posterior carapace short (less than length of was made based exclusively on the informa- shield), broad, den.sely setose, calcified. tion contained in de Saint Laurent's descrip- Antennal peduncles and acicles overreach- tion of this species. A recent examination of ing eyestalks; flagellum dorsoventrally the types as well as additional material of flattened; fourth segment armed with dor- this species has brought to light two signifi- sodistal spine. Epistomial spine absent. cant characters not mentioned in de Saint Eleven pairs of phyllobranchiae or interme- Laurent's original description: the presence diate branchiae. Right cheliped elongate; of paired pleopods in both sexes, and the palm rounded mesially, with weakly symmetry of the uropods and telson. These delimited dorsolateral margin. Left che- characters, together with the degree of cal- liped evenly calcified. Ambulatory legs cification of the shield, posterior carapace (second and third pereopods) long, well and tergites of the first and second abdomi- exceeding extended right cheliped; dactyls nal somites, clearly exclude this species from nearly .straight. Abdomen very short in Sympagurus or any other genus of Para- relation to ccphalothorax; tergites of first paguridae. Therefore. S. sinensis is herein and second somites well calcified; second 12 R. LEMAITRE somite with left pieuron terminating ventral- ond pleopods in the males and the second in ly in small subtriangular lobe. Telson and the females, are paired, and the telson and uropods symmetrical. Males with paired uropods are asymmetrical. Additionally, symmetrical first and second pleopods, and the only species in Bivalvopagurus, B. paired asymmetrical third to fifth pleopods; sinensis, most commonly uses a bivalve shell first and second modified as gonopods, first with an actinian to protect its very short with subtriangular distal lobe, second with abdomen, whereas species of Strobopagurus short exopod and strongly twisted distal use gastropod shells. segment; third to fifth pleopods biramous on left side, uniramous and reduced on right Bivalvopagurus sinensis side. Females with paired asymmetrical (de Saint Laurent, 1972) second to fifth pleopods, biramous on left Figs. 1-4 side (rami crossed on second to fourth), uniramous and reduced on right side. Parapagurus sinensis de Saint Laurent, 1972: 116, figs. 12,24. Type species. — Parapagurus sinensis de Sympagurus sinensis: Lemaitre, 1989: 37. Saint Laurent, 1972. Type material. — ^ holotype (SL 9.0 Etymology. — A compound name using mm), MNHN Pg. 1238; cf paratype (SL the mollusk class Bivalvia, in reference to 7.3 mm), MNHN Pg. 2239; Fisheries the common usage of a bivalve shell to Research Station Hong Kong, Cruise 7, shield its abdomen by the only species in the Station 55. Transect 172, 16'19.3'N, I14°29' genus. Gender: masculine. E, 220 m, [no date]. Remarks. — This new genus is most Additional material. — Philippines, closely allied to Strobopagurus Lemaitre, MUSORSTOM, Station 50, 25 March 1976, 1989. The two genera share a number of 13°49.2'N, 120°01.8'E, 415-510 m: 2 cf (SL characters: a broad shield, flattened anten- 9.7, 10.3 mm), I ? (SL 9.7 mm), 1 ovig. ^ nular fiagella, slender chelipeds, straight (SL 10.5 mm), USNM 265139; 61 cf (SL 7.0 dactyls of the ambulatory legs, and shape of -12.0 mm), 17 ^ (SL 5.5-9.0 mm), 56 ovig. the first and second pleopods in the males. ^ (SL 6.5-9.5 mm), MNHN. The pattern of lines and sulci on the poste- rior carapace is also similar in both genera, Redescription. — Shield (Fig. la, b) ap- although in Bivalvopagurus they are more proximately 1.3 times as broad as long, marked. However, in several important evenly calcified. Dorsal surface strongly characters, Bivalvopagurus is clearly distinct convex, densely "covered with fine setae. from Strobopagurus. In Bivalvopagurus, the Rostrum bluntly subtriangular, with low shield, posterior carapace, and tergites of dorsal ridge. Anterior margins straight. the first and second abdominal somites, are Lateral projections broadly subtriangular, well calcified. In contrast, in Strobopagurus with small terminal spine and I or 2 small the shield is weakly calcified, and the poste- spines lateral to terminal spine. Antero- rior carapace and abdominal tergites are lateral margins slightly sloping, often with soft, uncalcified. In the new genus, the small spine medially on one side. Lateral rostrum and lateral projections of the shield margins subparallel at least on anterior 1/2, are considerably more developed than in with setose lobe posteriorly. Posterior Strobopagurus. In Bivalvopagurus the margin broadly rounded. Posterior cara- pleopods are paired in both sexes, and the pace shorter than shield, densely covered telson and uropods are symmetrical, where- with fine setae (setae longer on branchio- as in Strobopagurus only the first and sec- stegite); cardiac sulcus extending to poste- A NEW GENUS OF PARAPAGLRIDAE 13 Fig. 1. Bivalvopagurus sinensis (de Saint Laurent, 1972), paralype, male. MNHN Pg. 2239: a, dorsal view of cephalothorax (including cephalic appendages and nnh pereopods), and abdomen showing portion of bivalve shell (s) and actinian wall (arrow); b, shield with cephalic ap(>enduges and anterior portion of branchiostegite, left lateral view; c. left basal antennular segment, dorsal view: d, right antennal peduncle, lateral view; e, ventral view of sternum of thoracic somites (including part of first to third pereopods, and fourth and fifth pereopods), showing bivalve shell (s) with actinian (arrow). Scales equal 4 mm (a, b, d, e), and 2 mm (c). 14 R. LEMAITRE Fig. 2. Bivahopagurus sinensis (de Saint Laurent, 1972), male (SL 10.3 mm), USNM 265139. Left mouthparts, internal view: a, mandible: b, maxillule; c, maxilla; d, first maxilliped; e, second maxilliped; f, third maxilliped. Scale equals 2 mm. A NEW GENUS OF PARAPAGHRIDAE 15 rior margin of carapace; sulcus cardiobran- with strong ventromesial distal spine. Sec- chialis short, weakly marked; linea ond segment with dorsolateral distal angle anomurica extending posteriorly nearly to produced, terminating in strong spine (occa- margin of carapace, bifurcated anteriorly sionally bifid or with additional small spine near shield (lateral branch of linea weakly ventrally); mesial margin with strong spine marked). on dorsodistal angle. First segment armed Ocular peduncles stout, half length of with 1-2 small spines on lateral face; shield, with short setae dorsally; corneae ventromesial angle produced, terminating in strongly dilated. Ocular acicies subtrian- 3-4 small spines. Antennal acicies exceed- gular, directed upward, terminating in ing distal margin of corneae by about 1/3 strong spine (occasionally bifid on one length of acicle; mesial margin armed with side); separated basally by slightly more 6-12 spines. than basal width of 1 acicle. Chelipeds dissimilar, slender, finely Mandible (Fig. 2a) with 3-segmented setose. Right chelipcd (Fig. 3a) with fingers palp. Maxillule (Fig. 2b) with external lobe crossing at tips when closed, terminating in of endopod weakly developed, internal lobe inwardly curved calcareous claws; cutting with long terminal seta. MaKilla (Fig. 2c) edge of fingers with irregularly sized calcare- with endopod slightly exceeding distal ous teeth. Dactyl about as long as palm, margin of scaphognathite First maxilliped with row of small spines on mesial margin; (Fig. 2d) with endopod subequal to exopod dorsal and ventral faces unarmed except for in distal extension. Second maxilliped (Fig. row of tufts of setae parallel to cutting edge. 2e) without distinguishing characters. Fixed finger with small spines on lateral Third maxilliped (Fig. 20 with crista margin (spines diminishing in size distally dentata formed of