Waikalasma dianajonesae, Chan & Chen & Rodriguez Moreno & Corbari, 2016

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 : 2973-2981

publication ID	https://doi.org/ 10.1080/00222933.2016.1226445
persistent identifier	https://treatment.plazi.org/id/03CA879A-FF81-5E50-A4E4-FB2DFC1AFCA2
treatment provided by	Felipe
scientific name	Waikalasma dianajonesae
status	sp. nov.

Treatment

Waikalasma dianajonesae sp. nov.

( Figures 9–14 View Figure 9 View Figure 10 View Figure 11 View Figure 12 View Figure 13 View Figure 14 ) Zoobank registration: urn:lsid:zoobank.org:act:AB9ABF5E-40D7-4B8D-812B-67755347A99C

Materials examined

Holotype. MNHN-IU-2013–7721 (1 specimen), Papua New Guinea, BIOPAPUA cruise, station CP3750, 05°39’S, 153°59 ʹ E, 654–660 m, 12 October 2010 GoogleMaps . Paratypes. MNHN-IU-2013-17871 (1 dissected specimen), Papua New Guinea, BIOPAPUA cruise, station CP3750, 05°39’S, 153° 59 ʹ E, 654–660 m, 12 October 2010; MNHN-IU-2013–7440 (4 specimens), Papua New Guinea, off Feni Islands , BIOPAPUA cruise, station CP3760, 03°58’S, 153°43 ʹ E, 613–660 m, 14 October 2010; MNHN-IU-2013-17872 (1 specimen), Solomon Islands, SALOMON 1 cruise, station DW1772, 8°16’S, 160°40 ʹ E, 570–756 m, 28 September 2001 GoogleMaps .

Diagnosis

Waikalasma with single row of relatively large imbricating plate (larger than W. boucheti ) at basal margin. Apex of carina pointing towards a horizontal direction. Mandible composed of 3 large, sharp teeth, third without serrations on cutting edge.

Description

Shell dirty cream in colour, composed of 8 solid plates including a C, paired CL1, CL2 and RL, and an R ( Figure 9 View Figure 9 (a–e)); shell plates sloping inwards from base towards orifice ( Figure 9 View Figure 9 (a–e)); basal region of external surfaces of plates surrounded by single row of 12 large, triangular imbricating plates ( Figure 9 View Figure 9 (a–e)), in single row, width of largest plates reaching 1/4 width of CL1 ( Figure 9 View Figure 9 (a–e)). C large, external surface with regular growth ridges; apex spout-like, anteverted, pointing in horizontal direction; external surface with 4 faint longitudinal ribs ( Figure 9 View Figure 9 (a–e)). 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 9 View Figure 9 (a–e)); internally only entering slightly into sheath. CL2 triangular, narrow, internally 1/3 of CL2 entering 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 concaved ( Figure 9 View Figure 9 (f, g)). Tergum inverted V-shaped, basal margin strongly, deeply excavated; carinal margin straight; scutal margin slightly concaved ( Figure 9 View Figure 9 (h, i)).

Cirrus I with rami sub-equal, posterior ramus 11-segmented, anterior ramus 10- segmented, both rami with serrulate setae ( Figure 10 View Figure 10 (a–d)). Cirrus II antenniform, rami with dense serrulate setae, setose compared to cirri III–VI ( Figure 10 View Figure 10 (e–h)); posterior ramus 25-segmented, anterior ramus 22-segmented. Cirri III–VI similar in morphology, long, slender. Cirrus III, posterior ramus 31-segmented, anterior ramus 27-segmented, both rami with serrulate setae; intermediate segments with 2 pairs of long and 2 pairs of short setae ( Figure 11 View Figure 11 (a–d)). Cirrus IV, posterior ramus 32-segmented, anterior ramus 30 segmented, intermediate segments of both rami with 2 pairs of long serrulate setae and 1 pair of simple setae; greater curvature bearing fan-shaped denticles ( Figure 11 View Figure 11 (e–h)). Cirrus V, posterior ramus 31-segmented, anterior ramus 32-segmented, rami with serrulate setae; intermediate segments of both rami bearing 2 pairs of long, serrulate setae and one pair of short, simple setae ( Figure 12 View Figure 12 (a–c)). Cirrus VI, posterior ramus 34- segmented, anterior ramus 36-segmented ( Figure 12 View Figure 12 (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 12 View Figure 12 (g, h)).

Maxilla bilobed, with serrulate setae around all margins; small maxillary lobe located at posterior region ( Figure 13 View Figure 13 (a–d)). Maxillule cutting edge strongly notched, lower portion of cutting edge prominent; 2 large setae and ~10 fine, small setae above notch ( Figure 13 View Figure 13 (e–h)), lower portion of cutting margin with> 20 large setae ( Figure 13 View Figure 13 (e–h)); dorsal margin of maxillule with fine, small setae. Mandible with 3 large teeth (excluding inferior angle), first separated slightly from second and third; lower margin straight, with 3 setae; inferior angle sharp, pectinate ( Figure 14 View Figure 14 (a–d)). Mandibular palp elongate, ovate, with serrulate setae at superior and inferior margins ( Figure 14 View Figure 14 (e, f)). Labrum concave, without cleft, row of fine, sharp teeth located at left and right end sides of cutting margin.

Etymology

In honour of Diana Jones, Executive Director of the Western Australian Museum, for her mentorship in barnacle taxonomy to BKKC and for her contributions to the studies of the family Pachylasmatidae in Southwest Pacific waters.

Distribution

At present, W. dianajonesae is only recorded in the waters of Papua New Guinea and the Solomon Islands, and is absent from those of New Caledonia and Vanuatu.

Remarks

Waikalasma dianajonesae sp. nov. is morphologically distinct from W. boucheti in the shape of the shell, the size of the imbricating plates and the form of the mandibles. The shell of W. boucheti is conical, with the apex of the carina pointing in an upward direction, whilst the shell of W. dianajonesae is depressed, with the apex of the carina pointing towards a horizontal direction. The imbricating plates of W. dianajonesae sp. nov. are larger than those of W. boucheti . Waikalasma dianajonesae differs from W. juneae in the size of its imbricating plates as well as the number of rows of imbricating plates. Waikalasma juneae has very small imbricating plates arranged in several whorls, in contrast to W. dianajonesae which has large imbricating plates, mostly arranged in a single row.

Molecular analysis results

A total of 601 and 309 bp of COI and 12S sequences were respectively obtained. The best-fit nucleotide substitution models for COI and 12S data sets were GTR + G and HKY + G, respectively. The genealogical relationship of Waikalasma for COI and 12S were congruent and were, therefore, combined together for further analysis. Of the 910 nucleotide combined data set, 244 were variable and 144 were parsimony informative. The genealogical topologies of NJ, ML and MP were highly similar, showing two wellsupported distinct lineages, corresponding to W. boucheti and W. dianajonesae sp. nov. ( Figure 15 View Figure 15 ). The best-scoring ML tree was shown with the node support values of all three methods ( Figure 15 View Figure 15 ). The evolutionary distance on COI and 12S based on mean K2P-distance was 16.5% and 10% between W. boucheti and W. dianajonesae sp. nov. The mean K2P distance was 0.1% and 0.3% for COI and 12S within W. boucheti , and 0.8% and 0.3% on COI and 12S within W. dianajonesae sp. nov., respectively.