Oxynaspis celata Darwin, 1852

Chan, Benny K. K. & Hayashi, Ryota, 2012, Epibiotic barnacles (Crustacea: Cirripedia: Thoracica) collected by the Kumejima 2009 Expedition, with descriptions of two new species *, Zootaxa 3367, pp. 21-48 : 30-33

Oxynaspis celata Darwin, 1852

( Figs. 2 C, 7, 8)

Oxynaspis celata Darwin, 1852: 134 , pl. 3, fig. 1. — Gruvel 1905: 103, fig. 114. — Nilsson-Cantell 1921: 226, fig. 37. — Nilsson Cantell 1937: 94. — Hiro 1937a: 51, fig. 42. — Totton 1940: 473, fig. 9. — Zevina 1968: 35. — Zevina 1982: 31, fig. 18. — Van Soyc & Dekelboum 2011: 5.

Material examined. RUMF-ZC-1557, one specimen (CL 7.9 mm) on an antipatharian coral, trawl 31, 26°18.785´N, 126°53.249´E, 13 Nov. 2009, depth 70.4–75.3 m.

Diagnosis (emended). Capitulum completely or nearly covered by 5 thin, fragile plates; surfaces often overgrown by antipatharian corals. Tergum with apex distally recurved; length of occludent margin half length of scutal margin. Umbo of scutum located in middle portion of occludent margin. Carina bowed; umbo located in proximal one third of carina, length of distal arm of carina about twice length of basal arm. Filamentary appendages absent. Caudal appendages minute, oval shaped, bundles of setae apically.

Description. Capitulum covered by 5 fully calcified, thin, fragile plates - carina, paired tergum and scutum ( Fig. 2 C); surface of plates overgrown by antipatharian corals. Tergum narrow, occludent margin half length of scutal margin, occludent margin slightly convex, apex of tergum recurved distally. Scutum trapezoid, umbo at middle of occludent margin, basal margin perpendicular to occludent margin, carinal margin convex. Carina bowed, umbo located in proximal one third of carinal margin, length of distal arm twice length of basal arm ( Fig. 2 C). Maxilla rounded, simple setae on all margins ( Fig. 7 A, B). Maxillule slightly notched, 2 large simple setae above notch, notch shallow with several fine simple setae, more than 10 longer, simple setae below notch ( Fig. 7 C, D). Mandible with 4 teeth, first well separated from remainder ( Fig. 7 E), lower margin very short, smooth ( Fig. 7 F), inferior angle terminating in 1 pectination ( Fig. 7 F). Mandibular palps elongated ( Fig. 7 G, H); dense, simple setae distally ( Fig. 7 H).

Cirrus I with anterior and posterior rami subequal, setae simple, anterior and posterior rami 12-and 8-segmented, respectively ( Fig. 8 A, B). Cirri II–VI ctenopod. Cirrus II with anterior and posterior rami 9-and 13-segmented, respectively ( Fig. 8 C), setae simple ( Fig. 8 D) and serrulate with very fine setules ( Fig. 8 E). Cirrus III with anterior and posterior rami 14- and 15-segmented, respectively, both rami with simple and serrulate setae. Cirrus IV with anterior and posterior rami 17-segmented, setae simple and serrulate. Cirrus V with both rami 16-segmented, setae simple and serrulate. Cirrus VI with anterior and posterior rami 16- and 17-segmented, setae simple and serrulate; intermediate segment of posterior ramus of cirrus VI with 3 pairs of long serrulate setae and 2 pairs of short simple setae ( Fig. 8 F). Caudal appendage oval uniarticulate, short (one third height of proximal segment of pedicel of cirrus VI), 4 simple setae distally ( Fig. 8 G). Penis long, half length of cirrus VI, pedicel of penis without basi-dorsal point ( Fig. 8 H).

Distribution. Atlantic Ocean (Madeira); Indian Ocean (Bay of Bengal); South China Sea (Beibu Gulf); Taiwan Strait; Japan; New Zealand,

Remarks. Darwin (1852) identified Oxynaspis celata from an antipatharian coral, Aphanipathes woollastoni , from Madeira, Atlantic Ocean ( Totton 1940). Subsequently, it has been widely recorded as four sub-species in the world’s oceans ( O. celata indica Annandale, 1909 ; also see Foster 1978; O. c. novazelandica Broch, 1922; O. c. japonica Broch, 1922 ; O. c. hirtae Totton 1940 ). Zevina (1982) revised the genus Oxynaspis and grouped O. c. japonica and O. c. indica as synonyms of O. celata , due to similarities in their external capitular morphology. Newman (1972) and Van Syoc and Dekelboum (2011) retained O. c. japonica , O. c. novazelandica, O. c. indica and O. c. hirtae as distinct sub-species of O. celata . Oxynaspis celata may be a cryptic species complex with high morphological variations in the world oceans and the taxonomy of this cryptic species group is unclear (see Foster 1978). Further studies should focus on the taxonomic status and population genetics of O. celata from different oceans in the world, using a combination of morphological and molecular approaches. In the present study we tentatively follow Van Syoc & Dekelboum (2011).

Oxynaspis c. japonica Broch, 1922 was collected from Nagasaki, Japan. The capitular morphology and the arthropodal characters (cirri and mouth parts) of the present specimen fit the descriptions of O. celata Darwin,1852 . Comparing the present specimen with O. c. japonica collected in Nagasaki, Japan ( Broch 1922), most of the morphology described for O. c. japonica is similar to the present specimen except for morphological differences exhibited by the labrum. Broch (1922) described the labrum of O. celata japonica as follows - “a deep and broad median furrow extends from between the palpi and its extreme top and makes the projecting end of the labrum appear a little cleft”. Such a deep and broad median burrow is absent from the labrum in the present specimen. Darwin (1852) did not mentioned the existence of such a furrow in the labrum of O. celata . The present specimen differs from O. c. indica as the opercular plate margins are smooth whereas those of O. c. indica have serrated margins (Table 1). The present specimen also differs from O. c. hirtae as the latter has an additional pair of filamentary appendages at the base of cirrus I (Table 1). Oxynaspis celata collected in the present study also differs from O. c. novazelandica, as the maxillule of O. c. novazelandica is strongly notched. Broch (1922: 278–279) described the maxillule of O. c. novazelandica as having “only three spines above the excavation (= notch) and the excavation is very broad, occupying almost half of the cutting edge….”. In the present study, the maxillule of the O. celata is slightly notched ( Fig. 7 C), differing from O. c. novazelandica which has a broad maxillular notch.

Figures

FIGURE 2. Kumejima epibiotic barnacles. A, Calantica arcuata n. sp. (Left, holotype, RUMF-ZC- 1554, middle, paratype, RUMF- ZC- 1555, note the tip of carina was broken, right, paratype, NMNS- 6690 - 001); B, Euscalpellum c. f. squamoum Hiro, 1937 (left, RUMF-ZC- 1556, right ASIZCR- 000225); C, Oxynaspis celata Darwin, 1852 (RUMF-ZC- 1557); D, Oxynaspis ryukyuensis n. sp. (holotype, RUMF-ZC- 1558); E, Poecilasma obliqua (Hoek, 1907) (RUMF-ZC- 1560); F, Platylepas hexastylos (Fabricius, 1798) (RUMF-ZC- 1561). A-E, lateral view for stalked barnacles; F, anterior view for Platylepas hexastylos. Scale bars in mm to indicate the size of specimens.

FIGURE 7. Oxynaspis celata Darwin, 1852 (RUMF-ZC- 1557). A, maxilla; B, magnified view of setae of maxilla; C, maxillule; D, cutting margin of maxillule; E, mandible; F, lower margin and inferior angle of mandible; G, mandibular palp; H, setae on the of mandibular palp. Scale bars in μm.

FIGURE 8. Oxynaspis celata (RUMF-ZC- 1557). A, cirrus I; B, simple type setae on cirrus I; C, cirrus II; D, simple type setae on cirrus II; E, simple type setae on cirrus IV; F, intermediate segment of posterior ramus of cirrus VI; G, caudal appendage; H, pedicel of penis. Scale bars in μm.