Waikalasma boucheti Buckeridge, 1996

Chan, Benny K. K., Chen, Hsi-Nien, Rodriguez Moreno, Paula A. & Corbari, Laure, 2016, Diversity and biogeography of the little known deep-sea barnacles of the genus Waikalasma Buckeridge, 1983 (Balanomorpha: Chionelasmatoidea) in the Southwest Pacific, with description of a new species, Journal of Natural History 50, pp. 2961-2984 : 2964-2973

publication ID	https://doi.org/ 10.1080/00222933.2016.1226445
persistent identifier	https://treatment.plazi.org/id/03CA879A-FF88-5E48-A4FB-F9BDFD54FBC6
treatment provided by	Felipe
scientific name	Waikalasma boucheti Buckeridge, 1996
status

Treatment

( Figures 2–8 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 View Figure 7 View Figure 8 )

Waikalasma boucheti Buckeridge, 1996: 449 , figs 1–4. – Jones 2000: 160, fig. 5.

Materials examined

MNHN-IU-2013–1996 (1 specimen), New Caledonia: Mont Vauban , EXBODI cruise, station DW3894, 22°24’S, 171°45 ʹ E, 843–845 m, 19 September 2011; MNHN-IU-2013-7540 (1 specimen) same data as MNHN-IU-2013–1996; MNHN-IU-2013–7587 (2 specimens) New Caledonia, Banc réfractaire, NORFOLK 2 cruise, station DW2103, 23°57’S, 167°44 ʹ E, 717–737 m, 30 October 2003; MNHN-IU-2013–7439 (1 specimen), Papua New Guinea, BIOPAPUA cruise, station DW3688, 03°04’S 147°32 ʹ E, 402–640 m, 28 September 2010 GoogleMaps .

Materials used for molecular studies only

Holotype. MNHN-IU-2013-11975 (ex Ci2428), Vanuatu, MUSORTOM 8 cruise, station CP1080, 15°57.4 ʹ N, 167°27 ʹ E, 799–850 m, 5 October 1994. GoogleMaps

Paratype. MNHN-IU-2013-11976 (ex Ci2506), Vanuatu, MUSORTOM 8 cruise, station DW1113, 14°53 ʹ N, 167°06 ʹ E, 700–736 m, 8 October 1994 GoogleMaps .

Diagnosis

Waikalasma with single or double rows of imbricating plates. Apex of C pointing in upward inclined direction. Mandible composed of three large sharp teeth, third with serrations on cutting edge.

Description (based on specimen MNHN-IU-2013-7540)

Shell dirty cream in colour, composed of 8 solid plates including a C, paired CL1, CL2 and RL, and an R ( Figure 2 View Figure 2 (a–d)); shell plates sloping inwards from base towards orifice ( Figure 2 View Figure 2 (a–d)); basal region of external surfaces of plates surrounded by single row of 16 triangular, imbricating plates, width of largest reaching 1/3 width of CL1 ( Figure 2 View Figure 2 (a–d)). C large, external surface with 4 faint, vertical, longitudinal ribs and regular growth ridges; apex spout-like, anteverted, pointing in upwardly inclined direction ( Figure 2 View Figure 2 (a–d)). External surfaces of CL1 and CL2 with regular horizontal growth ridges and single vertical longitudinal rib. CL1 triangular, height ~1.5 times basal width ( Figure 2 View Figure 2 (a–d)); internally only slightly entering into sheath. CL2 triangular, narrow, internally 1/3 of CL2 entering into sheath. RL narrow, radii wide. R oval shaped, alae narrow. Basis membranous.

Scutum triangular, height ~twice width, external surface with horizontal striations; inner surface smooth, adductor muscle and depressor muscle scars prominent; tergal margin slightly concave ( Figure 2 View Figure 2 (f, g)). Tergum inverted V-shape; basal margin strongly, deeply excavated; carinal margin straight; scutal margin with prominent articular ridge ( Figure 2 View Figure 2 (h, i)).

Cirrus I with rami sub-equal, posterior ramus 11-segmented, anterior ramus 13-segmented, both rami with serrulate setae ( Figure 3 View Figure 3 (a–d)). Cirrus II antenniform, rami with dense serrulate setae, more setose than cirri III–VI; posterior ramus 23-segmented, anterior ramus 19-segmented ( Figure 3 View Figure 3 (e–h)). Cirri III–VI similar in morphology, long, slender. Cirrus III, posterior ramus 24-segmented, anterior ramus 25-segmented, both rami with serrulate setae ( Figure 4 View Figure 4 (a–d)); intermediate segments with 2–3 pairs of long and 1 pair of short setae ( Figure 4 View Figure 4 (a–d)). Cirrus IV, intermediate segments of both rami with 2–3 pairs of long, serrulate setae and 1 pair of simple setae, greater curvature bearing fan-shaped denticles ( Figure 4 View Figure 4 (e–h)). Cirrus V, posterior ramus 29-segmented, anterior ramus 33-segmented, rami with serrulate setae; intermediate segments of both rami bearing 3 pairs of long, serrulate setae and 1 pair of short simple setae ( Figure 5 View Figure 5 (a–c)). Cirrus VI, posterior ramus 31-segmented, anterior ramus 30 segmented ( Figure 5 View Figure 5 (d–f)). Caudal appendages absent. Penis short, height less than basal segment of pedicel of cirrus VI, basi-dorsal point absent, tip of penis truncated ( Figure 5 View Figure 5 (g–h)).

Maxilla bilobed, with serrulate setae around all margins, small maxillary lobe located at posterior region ( Figure 6 View Figure 6 (a–d)). Maxillule cutting edge slightly notched, 2 large setae above notch, lower portion of cutting margin with> 20 large setae; dorsal margin with fine small setae ( Figure 6 View Figure 6 (e–h)). Mandible with 3 large teeth (excluding inferior angle), first separated slightly from second and third, cutting edge of third serrated with series of sharp spines; lower margin straight with> 8 large setae; inferior angle sharp, pectinate ( Figure 7 View Figure 7 (a–d)). Mandibular palp elongate, ovate, serrulate setae at superior and inferior margins ( Figure 7 View Figure 7 (e–f)). Labrum concave, without cleft; row of fine, sharp teeth located on left and right end sides of cutting margin of labrum ( Figure 7 View Figure 7 (g–h)).

Distribution

From the previous studies of Buckeridge (1996) and Jones (2000), W. boucheti has been recorded in the waters of Vanuatu and southern New Caledonia. In the present study, the distribution of W. boucheti is extended to south-western New Caledonian waters and Papua New Guinea.

Remarks

Waikalasma boucheti exhibits intra-specific morphological variation of the maxillules, mandibles and labrum. From the illustrations of the holotype of Waikalasma boucheti in Buckeridge (1996), the mandible has three teeth, with the lower margin short with a few long setae, the maxillule with a slight notch, with sparse setae on the cutting margin, and the cutting margin of the labrum concave, with small teeth. In the present study, specimens MNHN-IU-2013-1996 ( Figure 8 View Figure 8 (g–i)) and MNHN-IU-2013-7540 ( Figure 8 View Figure 8 (j–l)) have deeply notched maxillules. However, specimen MNHN-IU-2013-7587 ( Figure 8 View Figure 8 (m– o)) has a slightly notched maxillule, similar to the holotype of W. boucheti ( Figure 8 View Figure 8 (a–c)). The mandibles have three teeth, which is consistent in all specimens in the present study and the holotype ( Figure 8 View Figure 8 ). However, the third tooth of the mandible in all specimens studied in the present study has a serrated cutting edge ( Figure 8 View Figure 8 (h, k, n), serrated edge indicated by arrows) a feature not shown in the illustration of the holotype ( Buckeridge 1996). The cutting edge of the labrum is concave in the holotype illustration ( Buckeridge 1996) but the labrum in all the specimens in the present study is only slightly concave ( Figure 8 View Figure 8 ). Jones (2000) reported a single, incomplete specimen of Waikalasma in New Caledonia. Compared to the holotype illustrated by Buckeridge (1996), the maxillule of Waikalasma in Jones (2000) is slightly notched, the mandible has a shorter lower margin and the labrum is slightly concave ( Figure 8 View Figure 8 (d–f)). Based on such differences in the mandible and labrum between the W. boucheti holotype and the incomplete specimens from New Caledonia, Jones (2000) suspected the specimen collected in New Caledonia may be a separate species from Waikalasma boucheti , but due to the lack of complete specimens (MNHN-IU-2009–3831), concluded the New Caledonia specimen be regarded as Waikalasma boucheti , until further specimens can be collected to study intra-specific variations. In the present study, we have tried to sequence the incomplete samples of Waikalasma in Jones (2000) but failed to obtain informative information. However, due to the morphological variation in the mandibles and labrum of W. boucheti addressed in the present study, it is highly possible that the specimen in Jones (2000) belongs to W. boucheti .