Herentia andreasi, Berning & Tilbrook & Rosso, 2008

Berning, Björn, Tilbrook, Kevin J. & Rosso, Antonietta, 2008, Revision of the north-eastern Atlantic and Mediterranean species of the genera Herentia and Therenia (Bryozoa: Cheilostomata), Journal of Natural History (J. Nat. Hist.) 42 (21 - 22), pp. 1509-1547 : 1521-1524

Herentia andreasi new species

( Figure 3 )

Escharina hyndmanni: Norman 1909 , part: p. 302.

Differential diagnosis

H. andreasi differs from H. hyndmanni in having slightly larger zooecia, distinctly larger marginal pores, a broader gymnocystal rim surrounding the orifice, oral spines, a markedly elliptical sinus in autozooecia and a broader and U-shaped sinus in ovicellate zooecia, and in a larger, more proximally and centrally situated avicularium that is separated from the zooecium margin by areolar pores, and which is distinctly longer than the orifice. Furthermore, the thickened rim framing the distal orifice margin in autozooecia in H. hyndmanni is absent in H. andreasi .

H. andreasi is distinguished from H. majae due to the larger size of all skeletal features and areolar pores, a transversely-elliptical sinus and broader condyles in autozooecia as well as a much broader sinus in ovicellate zooecia, the presence of spines, and due to its more centrally positioned avicularium that is separated from the zooecium margin by areolar pores.

In contrast to H. thalassae , H. andreasi has a lower zooecium and ooecium relief, significantly smaller zooecia as well as primary orifices and apertures, larger marginal pores, one or two fewer oral spines, an elliptical sinus in autozooecia, and a slightly larger avicularium that is distinctly longer than the orifice and has a broader rostral margin.

Etymology

Named after the first author’s nephew, Andreas Rausch.

Material examined

Holotype: NHM 2007.10.9. 1, off Madeira, 75–90 m, on small rock . Paratype: NHM 2007.10.9. 2, off Madeira, 75–90 m, on polychaete tube . Additional material: NHM 11.10.1.1206, off Madeira, 75–90 m, one colony on rock .

Measurements

ZL 609¡58, 517–725 (2, 20); ZW 523¡74, 414–696 (2, 20); OL 127¡10, 118–153 (2, 20); OW 124¡12, 108–153 (2, 20); ApL 157¡9, 141–164 (1, 5); ApW 161¡6, 153– 167 (1, 5); OvL 265¡24, 233–294 (1, 5); OvW 369¡16, 344–385 (1, 5); AL 168¡12, 147–199 (2, 20); AW 135¡13, 110–157 (2, 20).

Description

Colony encrusting unilaminar, multiserial. Zooecia hexagonal to polygonal, separated by deep grooves; vertical walls with round to oval communication pores. Frontal wall more or less flat proximally, distally slightly rising towards orifice, surface smooth or slightly rugose, imperforate except for a row of 8–13 large marginal pores that become accentuated by thick ridges produced by secondary calcification, with the pores then tapering towards the zooecium centre. Orifice slightly elevated, distinctly dimorphic, anter horseshoe-shaped, distolateral orifice rim with an immersed narrow shelf; primary orifice in autozooecia about as broad as long and widest distal to mid-distance, proximal margin straight or slightly upturned, sinus broadly V-shaped, ending in a small transverse ellipse, condyles as long as proximal margin, narrowing in an increasing slope-angle towards sinus; aperture in ovicellate zooecia larger, proximal margin wider with a broadly Ushaped sinus, condyles distinctly narrower and sloping at a lower angle towards sinus. Primary orifice and aperture encircled by a broad band of smooth gymnocystal calcification. Six distolateral oral spines in the first zooid, reduced to two or three distal ones in adult autozooids.

Ooecium initially spherical, becoming semi-immersed by a frontal wall of distal zooecium; exposed surface a curved, flattened and thickened rim sloping proximally.

Avicularium situated proximolateral or occasionally proximal to orifice, at or slightly proximal to mid-distance of zooecium (with two or three marginal pores between avicularium and orifice) and at some distance from zooecium margin, cystid continuous with frontal wall; in earliest astogenetic zooecia the avicularium is situated near proximal zooecium margin, moving distally in later zooecia; rostrum a round or oval, broad and smooth rim sloping towards opesium, laterally or distolaterally oriented; mandible setiform, up to twice the length of an autozooid; crossbar bilateral symmetrical, strong, slightly arcuate with the apex at centre, proximal part of crossbar (with respect to long axis of rostrum) relatively narrow, margin straight or slightly concave when viewed from above, except from a small semicircular extension protruding from its basal centre, distal part of crossbar set off from the proximal part by a suture, calcification distinctly thickening towards the lateral rostral margins, creating a U-shaped distal margin.

An ancestrula was not observed; early astogeny as for genus.

Remarks

The original sample of the paratype (NHM 11.10.1.1203) comprised specimens of Herentia andreasi and Therenia peristomata n. sp. (see below), which Norman (1909) both referred to E. hyndmanni . He remarked (p. 302) that a ‘‘curious variety had a series of large pits all round the zooecia just within the outer margin’’ (5 H. andreasi ), while not realizing that the remaining specimens had a pseudoporous frontal wall and were thus even more curious.

The geographic distribution of H. andreasi is, at the current state of knowledge, restricted to the Madeiran archipelago. The colonies encrust rocks and calcareous substrata at depths of 75–90 m.

Figures

Figure 3. Herentia andreasi n. sp., off Madeira. (A, C) Paratype, NHM 2007.10.9.2; (B, D) holotype, NHM 2007.10.9.1. (A) Autozooecia at the colony growth margin; note the incompletely formed frontal wall in zooecium at left and the uncalcified central area in the basal wall of the incompletely formed zooecium at top of image; (B) auto- and ovicellate zooecia during later ontogeny; (C) close-up of orifice and avicularium; (D) close-up of ovicellate zooecium; note the different shapes of sinus and condyles compared to orifice of autozooecium. Scale bars: 200mm (A, B); 50 mm (C, D).