Chelarctus aureus ( Holthuis, 1963 )

Yang, Chien-Hui, Lin, Chia-Wei & Chan, Tin-Yam, 2014, Additional slipper lobsters of the subfamily Scyllarinae Latreille, 1825 (Crustacea, Achelata, Scyllaridae) from Taiwan, Zootaxa 3852 (3), pp. 336-346 : 340

Chelarctus aureus ( Holthuis, 1963)

( Figs. 3 , 6 B)

Scyllarus aureus Holthuis 1963: 59 (type locality: the Philippines).

Chelarctus aureus .— Holthuis 2002: 578, figs. 28–29.— Zhang & Liu 2006: 20, figs 3, 4-5.—Chan 2010: 161, fig. 5E.

Material examined. Pingtung County, Donggang fishing port, commercial trawler, 120 m, 23 Sep 2004, 2 females 11.95–14.43 mm cl ( NTOU M01288 ).

Diagnosis. Rostral and gastric teeth distinct. Pregastric tooth absent. Cardiac tooth replaced by 2 blunt squamiform tubercles. Orbital carina smooth. Anterior branchial carina much more elevated than posterior branchial carina. Medial incision at posterior margin of carapace weak. Abdomen with arborescent sculpture, median carina absent. Articulating surface of abdominal tergites II–V with 2 transverse setose grooves. Posterior margins of abdominal tergites I–IV not medially incised. Abdominal pleura II–IV ending in sharp point. Anterior margin of antennal segment VI with 4 or 5 sharp and slender teeth. Antennal segment IV without additional carina, anterior margin bearing only 1 tooth, outer margin with 2 large teeth. Propodi of pereiopods II and III each with anteroventral tooth and 2 parallel longitudinal setose grooves on lateral surface. Dactylus of pereiopod IV longest in all pereiopods, merus with well-developed alate carina on ventral surface. Anterior part of thoracic sternum produced forward, with small triangular medial incision. Thoracic sternites III–V each with well-developed median tubercle.

Coloration. Body generally pinkish brown or tan. Outermost tooth on antennal segment VI and oblique carina on antennal segment IV dark purplish brown. Antennal segment IV and posterodorsal part of carapace with golden iridescence. Gastric area somewhat having a pair of purplish spots. Pereiopods, abdominal somite VI and tailfan pale whitish brown to white. Eyes light brown.

Distribution. Western Pacific and the South China Sea. Reported from the South China Sea north of Sarawak, the Philippines, Indonesia, Fiji, and now extended northwards to Taiwan; at depths of 100– 200 m.

Remarks. Chelarctus aureus is unique amongst all the scyllarines with coloration known in having golden iridescence (also see the color photograph from the Philippines material in Chan 2010). With the recent addition of Chelarctus virgosus Yang and Chan, 2012 , the genus Chelarctus now contains four species. Previously only C. virgousus was reported from Taiwan (sometimes reported under the name C. cultrifer ). Chelarctus aureus differs from the other species of the genus in the pereiopod II instead of pereiopod IV being subchelate.

Figures

FIGURE 3. Chelarctus aureus (Holthuis, 1963), female 14.3 mm cl (NTOU M 01288): A, carapace, dorsal view; B, thoracic sternum; C, pereiopod I; D, pereiopod II; E, pereiopod III; F, pereiopod IV; G, pereiopod V. All right pereiopods. Scales = 5 mm.

FIGURE 6. A, Bathyarctus rubens (Alcock and Anderson, 1894), male 14.9 mm cl (NTOU M 01283); B, Chelarctus aureus (Holthuis, 1963), female 14.3 mm cl (NTOU M 01288); C, Crenarctus bicuspidatus (De Man, 1905), male 11.8 mm cl (NMMBCD 4007); D, Petrarctus veliger Hothuis, 2002, female 19.4 mm cl (NMMBCD 4008).