Spiropagurus monospinosus Han, An & Sha, 2016, sp. nov.
Creators: name: Han, Yuan-Yuan
name: An, Jian-Mei
name: Sha, Zhong-Li
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Paguridae
Spiropagurus
Spiropagurus monospinosus

description: Spiropagurus monospinosus sp. nov.
(Figs. 1–3)
Material examined. Holotype: male, MBM 179906, 7.10 mm, Beibu Gulf, 8 April 1956, Station 56-344, coll. Rui- Yu L iu. Allotype: ovigerous female, MBM 119965, 5.95 mm, Nansha island, 13 May 1987, 46 m. Paratype: 1 male, MBM 151243 -1, SL 7.25 mm, Nansha island, 14 May 1989, 53 m, Station 33 (9°20'N, 108°52'E), Agassiz trawl.
Description. Shield (Fig. 1 a) 1.2 times broader than long; anterolateral margins sloping; anterior margin convex in middle; anterior margin between rostrum, and lateral projections shallowly concave; rostrum broadly rounded or broadly subtriangular, not reaching level of lateral projections; anterior margin with row of short stiff setae. Lateral projections prominent, each with laterally directed submarginal spine; posterior margin roundly truncate; dorsal surfaces with some paired tufts of setae, 2 longitudinal rows of setae in middle.
Ocular peduncles (Fig. 1 a) short, 0.60–0.70 as long as shield, slightly flattened dorsoventrally; surfaces without ring of stiff setae at base of cornea and only few tufts of very short setae dorsally and mesially; corneas strongly dilated, corneal diameter about 0.70–0.80 ocular peduncle length; ocular acicles broadly subovate.
Antennular peduncles (Fig. 1 a) long, about twice length of ocular peduncle. Ultimate segment with longitudinal row of tufts of stiff setae on dorsal surface. Penultimate segment with few short setae. Basal segment with short setae dorsally and distally.
Antennal peduncles (Fig. 1 a) nearly as long as antennular peduncles, fifth segment with few long setae dorsally and distally; fourth segment with long stiff setae on mesial surface; third segment with small spine at ventrodistal angle partially concealed by long stiff setae; second segment with dorsolateral distal angle produced, overreaching base of fourth segment, terminating in simple spine, lateral and mesial faces with few scattered setae; first segment with dorsolateral margin unarmed, ventrodistal angle with tufts of long setae. Antennal acicles moderately long, overreaching base of fifth peduncular segment, slightly arcuate, terminating in acute spine, fringed on both edges with very long. Antennal flagella long, overreaching tip of right cheliped; articles naked or with occasional short setae.
Mandible (Fig. 1 b) without distinctive features. Maxillule (Fig. 1 c) with proximal endite subquadrate; endopod with one setae on slightly produced inner lobe, outer lobe very well developed, slightly recurved. Maxilla (Fig. 1 d) with endopod inflated basally, overreaching anterior margin of scaphognathite. First maxilliped (Fig. 1 e) with endopod approximately two-thirds length of exopod; exopod strongly expanded proximally. Second maxilliped (Fig. 1 f) with basis to ischium fusion incomplete. Third maxilliped (Fig. 1 g) with ischium (Fig. 1 h) bearing well developed crista dentata and one accessory tooth.
Chelipeds subequal in length; right (Fig. 2 a–d) somewhat larger than left (Fig. 2 e–h); stiff setae arising from transverse scutes or ridges. Right chela about 3 times longer than broad. Dactylus slightly longer than palm, dorsomesial margin not delimited, mesial face with short vertical ridges, ventral surfaces unarmed, with two longitudinal rows of tufts of long setae, cutting edge with row of tiny, slender calcareous teeth, terminating in minute calcareous claw. Palm 0.70–0.80 length of carpus, dorsal surface creased by series of transverse rows of setae; proximal 0.50–0.60 of dorsal surface of fixed finger with irregular transverse rows of short scutes provided with long stiff setae, distal 0.50–0.40 of dorsal surface of fixed finger nearly smooth, with only scattered tufts of setae; lateral face and mesial face of palm and lateral face of fixed finger with longitudinal ridges, each provided with short to long stiff setae, ventral surfaces of palm and fixed finger with scattered tufts of moderate to long setae. Carpus slightly longer than merus, becoming noticeably broader distally; dorsodistal margin with row of short stiff setae, dorsomesial margin with row of moderately strong spines partially obscured by long stiff setae, dorsolateral margin not delimited; dorsal surface with transverse rows of ridges provided with short to long stiff setae extending to lateral face; lateral faces with longitudinal ridges and moderate to long setae; ventral surface with short transverse scutes and moderate to long setae. Merus with transverse ridges dorsally, mesial and lateral faces each with short transverse ridges and long stiff setae; ventrolateral margin with one prominent spines, ventromesial margin not delimited, each margin with irregular transverse rows of short scutes provided with short stiff setae; ventral surface with tufts of moderately long setae. Ischium with rows of setae; one spine at ventrolateral distal angle.
Left cheliped (Fig. 2 e–h) slender. Dactylus slightly longer than palm, cutting edge with row of calcareous teeth, terminating in small corneous claw and slightly overlapped by fixed finger; dorsal surface with tufts of setae; mesial face with short vertical ridges; ventral surfaces unarmed, with two longitudinal rows of tufts of long setae. Palm 0.75–0.85 length of carpus; dorsomesial margin not delimited; dorsal surface, like that of right, with transverse rows of ridges provided with long stiff setae, extending to lateral and mesial faces; dorsolateral margin and dorsomesial margin each with a longitudinal row of tufts of long setae. Carpus approximately equal to or slightly longer than merus; dorsodistal margin with row of short to moderately long stiff setae; dorsomesial margin with row of moderately strong spines, partially obscured by long stiff setae; dorsolateral margin not delimited or only with a spine on the dorsolateral distal margin, but never forming a row; dorsal surface with transverse rows of ridges provided with short to long stiff setae extending to lateral face; mesial and ventral surfaces with short transverse ridges each bearing long stiff setae, lateral surfaces with longitudinal ridges and moderate to long setae. Merus with short, transverse ridges and tufts of moderately long setae on proximal half of dorsal surface; lateral and mesial faces with few transverse ridges bearing row of long setae; ventral surface unarmed, ventrolateral margin with few small spines and one prominent spines, with rows of scutes bearing long stiff setae; ventromesial margin not delimited, also with rows of scutes bearing long stiff setae.
Ambulatory legs (Fig. 3 a–f) slender; right second pereopod (Fig. 3 b, c) overreaching tip of right cheliped by 0.10–0.20 length of dactylus. Dactyli very slender, 1.15–1.25 times as long as propodi in second pereopods (Fig. 3 b, c, e, f), 1.40–1.60 times as long in third pereopods (Fig. 3 a, d); in lateral view, nearly straight to curved ventrally; in dorsal view, strongly twisted in distal 0.30–0.50; each pereopod terminating in small corneous claw; dorsal surfaces each with single row of long spiniform setae; lateral faces each with trace of median sulcus bearing rows of tufts of long setae. Propodi distinctly longer than carpi; dorsal surfaces each with 7–9 small calcareous spines; lateral and mesial faces with traverse rows of ridges provided with long stiff setae; ventral surfaces with 2– 4 small calcareous spines at ventrodistal angle. Carpi shorter than meri; dorsal surfaces each with one row of calcareous spines; mesial faces and lateral faces each with several short to moderately long, transverse rows of stiff setae; ventral surfaces unarmed. Merus each with row of transverse ridges and stiff setae on dorsal surfaces, 3–5 calcareous spines at dorsodistal proximally; lateral faces each with several short to moderately long, transverse rows of stiff setae; mesial faces only with few tufts of setae. Ischium each with setae dorsally and ventrally.
Fourth pereopods (Fig. 1 i) with numerous stiff setae on dorsal surfaces of propodi, carpi and meri; propodal rasp composed of 2–4 rows of corneous scales.
Male with stout, long, coiled sexual tube (Fig. 3 g) on coxa of left fifth pereopod, gonopore on right partially concealed by tuft of stiff setae.
Anterior lobe of sixth thoracic sternite (Fig. 1 j) nearly flattened, with tufts of setae on surface.
Abdomen strongly twisted, with 3 unpaired left pleopods in male and 4 unpaired left pleopods in females. Uropods strongly asymmetrical. Telson (Fig. 3 h) with acutely triangular posterior lobes separated by extremely deep median cleft; each lobe with prominent corneous-toothed mesial margin, lateral margins each usually with 1 or 2 well-developed, often corneous-tipped spines.
Etymology. Derived from “mono” meaning single, and “spina” meaning spine, alluding to the single spine row on carpus of the cheliped.
Distribution. Presently known only from the Beibu Gulf and Nansha islands in the South China Sea; 46– 53 m.
Habitat. Sandy-mud, occupying shells of the gastropod Glossaulax.
Remarks. Spiropagurus monospinosus sp. nov. is unique in the genus by the carpus of the chelipeds having only one longitudinal row of spines. This new species is morphologically most similar to S. profundorum, and it differs from the latter by the following characters: the new species only bears one row of spines on the carpus of the chelipeds rather than two rows of spines in S. profundorum; the new species bears no spine or only one spine on the distal margin of the carpus of the chelipeds rather than 4–6 spines in S. profundorum; the new species bears 6 spines in the median cleft of the telson, while S. profundorum bears 8–10 spines.
description: Published as part of Han, Yuan-Yuan, An, Jian-Mei & Sha, Zhong-Li, 2016, A review of the genus Spiropagurus Stimpson, 1858 (Crustacea: Decapoda: Paguridae) from the China seas, pp. 75-89 in Zootaxa 4175 (1) on pages 76-77, DOI: 10.11646/zootaxa.4175.1.7, http://zenodo.org/record/160308