Bryopesanser capitaneus Tilbrook, 2006

Tilbrook, Kevin J., 2012, Review of the bryozoan genus Bryopesanser Tilbrook, 2006 (Escharinidae: Cheilostomata) with the description of 11 new species, Zootaxa 3165, pp. 39-63 : 42-44

Bryopesanser capitaneus Tilbrook, 2006

( Figures 5–7 , Table 1)

Mastigophora pesanseris: Canu & Bassler 1929 (part): 412.

Escharina pesanseris: Harmer, 1957 (part): 998, pl. 67, fig. 13. Escharina pesanseris: Liu et al. 2001: 605 , pl. 51, figs 1–3.

Bryopesanser capitaneus Tilbrook, 2006: 256 , pl. 55E, pl. 56D–F.

Material examined. Holotype: NHMUK 2000.2.23.8 (56.E) Siboga Station 80, Borneo Bank, Strait of Makassar, 2°25’ S, 117°43’ E, 40–50 m, 13.09.1899. Other material examined: USNM 8221, Albatross Station 5179, off Romblon Light, Romblon, 68 m (37 fms).

Description. Autozooids large, 0.80–1.00 x 0.60–0.80 mm, irregularly polygonal, separated by shallow grooves. Frontal shield smooth, slightly convex, with small multiporous pores; areolar septular pores small, in lateral and proximal corners of each zooid. Primary orifice slightly longer than wide, ca 0.13 x 0.11 mm excluding sinus, anter deeply arched, proximal border straight or slightly concave; condyles minutely denticulate, shallow; sinus drop-shaped, wider than long. Autozooids with 7 regularly spaced oral spines, ovicellate zooids with 6 oral spines, the distalmost pair slightly incorporated into the ovicell. Proximal peristome raised, a spire-like median mucro developing with ontogeny. Avicularia lateral to most proximal pair of spines, distomedially directed; rostrum medium-sized, open-ended; crossbar complete; mandible fan-shaped. Ovicell with raised process frontally. Ancestrula as long as wide, ca 0.40 x 0.40 mm; 10 spines, 5 closely spaced distally, 5 widely spaced proximally; opesia occupying less than one quarter of frontal surface.

Remarks. Bryopesanser capitaneus is characterised by the large size of its autozooids, its multiporous frontal pores, the morphology of the primary orifice, and the peristome developed into a proximal mucro. The position of the distomedially directed avicularia is also characteristic. Tilbrook (2006) noted that B. capitaneus is able to produce brooding colonies with fewer than 10 autozooids.

Bryopesanser capitaneus differs from B. pesanseris in the size of its autozooids and its frontal shield with multiporous pores. B. capitaneus develops a peristomial umbo similar to B. pesanseris and B. lobiones n. sp.; these differ from B. latesco and B. grandicella , which produce flared peristomes. The possession of multiporous frontal pores is not unique to B. capitaneus ; they are also developed by B. grandicella , B. gardineri n. sp. and B. lobiones n. sp. However, attributes of the primary orifice and the peristome enable these five species to be distinguished.

Harmer (1957: pl. 67, fig. 13) figured the ancestrula on the type specimen of Bryopesanser capitaneus . The material that Liu et al. (2001) illustrated bears a striking resemblance to Tilbrook’s (2006) species, and is placed in synonymy here pending further examination of their material.

It is worth noting that examination of specimens from the Philippines, including those of Canu & Bassler (1929) originally assigned to B. pesanseris , has revealed three different species ( B. capitaneus , B. latesco and B. tonsillorum n. sp.).

Distribution. Bryopesanser capitaneus is found in the Nansha and South China Seas off China ( Lu 1991; Liu et al. 2001), the Makassar Strait, and Honiara, Guadalcanal, Solomon Islands.

Figures

FIGURES 5 – 7, Bryopesanser capitaneus. 5, 6, Holotype specimen, NHMUK 2000.2. 23.8, Strait of Makassar; 6, USNM 8221, Romblon. Scale bars: 5, 200 µm; 6, 50 µm; 7, 500 µm.