Bryozobia rossi Yu, Kolbasov & Chan

Yu, Meng-Chen, Kolbasov, Gregory A. & Chan, Benny K. K., 2016, A new species of sponge inhabiting barnacle Bryozobia (Archaeobalanidae, Bryozobiinae) in the West Pacific, ZooKeys 571, pp. 1-20 : 5-11

Taxon classification Animalia Sessilia Archaeobalanidae

Bryozobia rossi Yu, Kolbasov & Chan sp. n. Figures 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

Type species.

Bryozobia synaptos Ross & Newman, 1996

Materials examined.

Holotype: Taiwan, Taitung, Green Island (Lyudao), Ziping, 22°37.99'N, 121°29.99'E, depth 24 m, November 15, 2011, coll. J.H.Y. Yu, ASIZCR-000338, on host sponge Agelas nakamurai (Hoshino, 1985), NPUST.POR.0357.

Paratypes: ASIZCR-000339, ASIZCR-000340 and Mg. 1222

Other materials.

Taiwan, Taitung, Orchid Island (Lanyu Island), Rock Shuangshihyen, 22°05.14'N, 121°34.10'E, depth 24 m, June 11, 2011, coll. J.H.Y. Yu, CEL-SOI33-1, on host sponge Theonella aff. conica (Kieschnick, 1896), NPUST.POR.0354.

Other materials: Japan, Nishidomari, Kochi, 32°46.48'N, 132°43.89'E, depth 5 m, July 22, 2011, coll. J.H.Y. Yu, CEL-SJP5-1, on host sponge Theonella mirabilis (de Laubenfels, 1954), NPUST.POR.0350.

Diagnosis.

Shell with unfused sutures, external surface with a few calcipeds and indistinct longitudinal ribs, vestige of CL2 with elevated interparietal portal on each side, an irregular whorl of open portals, and edges of parietal footings that may merge to completed portals. Calcareous base, base flat or saucer-shaped with numerous radial atria (app. 24) permeated by dense, irregularly shaped pores. Scutum with a prominent articular ridge, articular furrow low, concave pits of adductor and depressor muscles. Broad tergum with a beak-shaped apex, high and short articular ridge, and sloping spur.

Description.

White shell, tinged pinkish toward apex, with a maximal height range of 3-3.7 mm, basal diameter range of 3.3-4.6 mm, orifice range of 1.0-1.3 mm, and six plates (R-CL1-CL2-C) with unfused sutures, roughened and plicated exterior parietes with fine growth lines and few finger- and blade-like calcareous calcipeds on the surface (Figures 3, 4 A–D, 5 A–L, 6C, D, F, I–K, 7); smooth and digitate longitudinal ribs in the parietes base extending to the parietal footings that may merge and form completed portals (Figures 3, 4 A–F, 6A, B, D, F, G, 7 C–E); a whorl of rare interparietal and parietal portals in the shell base, two interparietal portals below rudimentary CL2 slightly elevated; plates eliminated at half the total length of the shell (Figures 3, 4C, D, 5 G–J, 6B, D, G, H, I, K, 7B, D, G, H). All portals were open and attached to the basal atria through arched sliced fillets (Figures 3, 4C, D, F, 6A, B, D, G, H, I, K, 7B). All plates, except CL2, were wide and triangular, with irregular basal margins and internal longitudinal ribs rostrum being the biggest (Figures 3, 4 A–D, 5 A–L, 6 A, I, K, 7 A–E, G, H). The smallest CL2 were irregularly rectangular two–three times shorter than other plates (Figures 3, 4C, D, 5 G–J, 6I, J, K, 7 A–E, G, H). Radii transparietal, summits slightly oblique, triangular, solid, horizontally striated (Figures 3, 4 B–D, 5 A–J, 7A, B). Alae developed in the summits almost horizontally. Sheath developed approximately one-fifth in the carina and one-third to one-half of the total height in other plates (Figures 5 A–L, 7 E–H). Calcareous base, flat or saucer-shaped with less than twenty atria, atria width approximately 0.1 mm, permeated by irregularly shaped small and dense pores were solid, radial, and indistinct calcipeds with separated atria, radiating from the center and extending out to basal margin and attached to the longitudinal ribs of parietes (Figures 4E, F, 5M, N, 6A, E, 7C, E).

Externally, scutum (Figure 4G, H) with horizontal growth ridges, without longitudinal striation; teeth present in the upper half of occludent margin; slightly bisinuous basal margin, strongly prominent articular ridge, approximately two-thirds the height of articular margin, articular furrow low, central adductor ridge, short, feeble, faint, and long depression for adductor muscle, and deep depressor and rostral muscles pits, lie directly at the basal margin. Tergum (Figure 4I, J) thin and semitransparent, nearly flat, with a beak-shaped apex; short and prominent articular ridge, broad articular furrow, without crests of depressor muscles; sloping spur not distinctly separated from the basiscutal angle of scutal margin, width approximately half of the basal margin, acute basiscutal angle; basal margin concave in the middle, wide and shallow spur furrow.

Labrum bilobed, separated by deep V-shaped notch (Figure 8A, B), with two or three small teeth on each side of the crest (Figure 8B).

Mandibular palp ovate with concave outer margin (Figure 8C, D), dense serrulate setae along the outer margin and tip (Figure 8E).

Mandible with five teeth (Figure 8F), second and third teeth bifid, upper margin bearing simple setae (Figure 8G) and the inferior angle ending in blunt angle with stout simple setae (Figure 8H).

Maxillule with a straight cutting edge and seven large cuspidate setae, and the upper and lower pairs largest (Figure 9A); upper margin with three pairs of simple setae and the lower margin with numerous simple setae (Figure 9 B–D).

Maxilla bilobed, with a triangular distal portion with a truncated outer edge (Figure 9E), base without setae, outer edge of the distal lobe with simple setae (Figure 9F, H), the inner edges of lobes straight, and thick serrulate setae along the inner edges of lobes (Figure 9G, H).

Cirrus I with unequal rami, anterior ramus with eleven segments, twice as long as the posterior ramus (five segments; Figure 10A), a protopod without setae at the anterior margin, with a tuft of plumose setae at the posterior margin (Figure 10A, B), and both the rami with serrulate setae on the intermediate segments, and bidentate and serrulate setae on the distal ends of anterior and posterior rami, respectively (Figure 10C, D).

Cirrus II with unequal rami, posterior ramus (six segments) shorter than the anterior (eight segments; Figure 10E), a protopod with plumose setae at the anterior margin and a tuft of plumose setae at the posterior margin (Figure 10F), the intermediate segments of both the rami with serrulate setae, and the distal ends of both the rami with bidentate setae (Figure 10G, H).

Cirrus III with subequal rami, a ten-segmented posterior ramus, nine-segmented anterior ramus (Figure 11A), a protopod with serrulate setae at the anterior margin and plumose setae at the posterior margin, the intermediate segments of both the rami with serrulate setae, distal ends of both the rami with bidentate and serrulate setae (Figure 11A, B).

Cirrus IV with unequal rami, a twelve-segmented anterior ramus, a posterior ramus broken with eleven segments on its remaining part (Figure 11C), a protopod with short setae having three curved teeth on the anterior margin (Figure 11D), proximal segments of the anterior ramus with one or two curved teeth (Figure 11E, F), intermediate segments of the anterior ramus with two pairs of long and short serrulate setae, intermediate segments of the posterior ramus with three pairs of long, medium, and short serrulate setae (Figure 11F, G), and the last segment of the anterior ramus with serrulate setae (Figure 11H).

The cirri V and VI were similar in length, with the anterior rami of cirri V and VI both having twenty-one segments, and the posterior rami of cirri V and VI were both broken, with nine and fifteen segments on their remaining parts, respectively. A short and simple protopod was observed on the anterior margin and long serrulate setae on the posterior margin (Figure 12A, D), intermediate segments of both the rami with three pairs of long, medium, and short serrulate setae, and the last segments of both the rami with serrate setae (Figure 12B, E, C).

The penis was approximately the same length as the cirrus VI, finely annulated, gradually tapering at the tip (Figure 12G), with a vestigial basidorsal point (Figure 12H), and long scarce setae scattered along the penis (Figure 12G, I).

Etymology.

We named the organisms after the famous cirripedologist late Prof. Arnold Ross (Scripps Institution of Oceanography, USA), who discovered the subfamily Bryozobiinae.

Remarks.

All previously described specimens of Bryozobia synaptos from Madagascar and Mauritius and Bryozobia sp. from Sri Lanka possess several (two to three) more or less regular whorls of shell portals ( Ross and Newman 1996, Van Syoc and Newman 2010). The interparietal portal below CL2 belonging to the first elevated whorl eliminates this plate; therefore, the shell becomes four plated below this whorl. All studied specimens of Bryozobia rossi do not have the first elevated whorl of several portals; however, only a pair of interparietal portals below CL2 eliminated these plates. Bryozobia rossi is characterized by a single irregular basal whorl of portals situated at the same level as the basal hemiportals and this differentiates the new species from the previously discovered forms of Bryozobia . Each whorl of shell portals is added ontogenetically and the sizes of studied specimens are similar to those studied from Indian Ocean, revealing that the new species has less number of whorls of portals compared with the previously described species. Although Bryozobia rossi has less number of portals and whorls of portals, it belongs to the genus Bryozobia because it has short, eliminated CL2 and open portals remaining attached to with the basal atria through tubular fillets. Opercular plates of Bryozobia rossi were similar to those in Bryozobia synaptos (absent in the specimens of Bryozobia from Sri Lanka).

The previously described Bryozobia from Madagascar, the Mascarene Plateau and Sri Lanka states that the radii between the R-CL1 are obsolete, whilst radii between R-CL1 in Bryozobia rossi sp. n. in the present study is well developed. In addition, the original diagnosis of Bryozobia from Madagascar and the Mascarene Plateau did not include parietal calcipedia, in which this character is present in Bryozobia rossi sp. n. In the present study, we conclude it is premature to modify the diagnosis of Bryozobia due to whether these discrepancies are ecotypic or specific differences is unknown. We propose to include Bryozobia rossi as incertae sedis in Bryozobia , deferring a decision as to whether or not it is a new genus in the Bryozobiinae when further molecular phylogenetic analysis is conducted in bryozobiine species.

The previously studied specimens of Bryozobia were represented by subfossil materials. The present description is the first for the morphology of the oral cone, cirri, and penis in this genus. Their morphology does not differ considerably from that in other bryozobiines, and cirrus IV with recurved teeth, characteristic of most of these barnacles. This is a first discovery of Bryozobia in Pacific; the previous ones were from the Indian Ocean.