Herentia majae, 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 : 1519-1521

Herentia majae new species

( Figure 2 )

Differential diagnosis

H. majae differs from all other species presented here in that there is no marginal pore situated between avicularium and orifice, in having a distinctly narrower apertural sinus in ovicellate zooecia as well as an asymmetrically shaped avicularian crossbar. In contrast to H. hyndmanni , the morphologically closest related species, it has slightly smaller zooecia as well as orifices and apertures, narrower condyles (especially in the aperture), and an avicularian cystid with one or two proximal areolar pores.

H. majae is distinguished from H. andreasi n. sp. due to smaller skeletal characters and marginal areolar pores, a U-shaped sinus and narrower condyles in autozooecia, the absence of oral spines and the contemporaneous presence of the thickened rim framing the distal orifice margin, and the extremely marginal position of the avicularium.

Compared to H. thalassae , all skeletal features are distinctly smaller in H. majae . Furthermore, the zooecium and ooecium relief is lower, the condyles are narrower, oral spines are absent, whereas the thickened rim at the distal orifice margin exists, and the avicularium is situated directly proximolateral to the orifice and abutting the zooecium margin.

Etymology

Named for the collector of the specimens, Maja Novosel.

Material examined

Holotype: CNHM Inv.br. 30, off Lastovo Island , Adriatic Sea, 30–40 m, on Adeonella pallasii (Heller) . Paratype: CNHM Inv.br. 31, Jabuka Shoal, Adriatic Sea, 40–50 m, on Pentapora fascialis (Pallas) .

Measurements

ZL 485¡30, 417–551 (2, 20); ZW 374¡33, 320–447 (2, 20); OL 93¡6, 85–107 (2, 18); OW 102¡4, 94–109 (2, 18); ApL 104–110 (1, 2); ApW 129–130 (1, 2); OvL 165; OvW 235; AL 107¡6, 100–122 (2, 20); AW 80¡5, 69–89 (2, 20).

Description

Colony encrusting unilaminar, multiserial. Zooecia hexagonal to polygonal, separated by deep grooves; vertical walls with a single, relatively small, round to oval communication pore per neighbouring zooid. Frontal wall more or less flat but sloping at and towards zooecium margin, surface finely granular, imperforate except for a row of four to eight marginal pores, plus one or two areolar pores associated with the avicularian cystid that are slightly offset from the zooecium margin. Orifice dimorphic, distolateral orifice rim with a very narrow immersed shelf; primary orifice in autozooecia slightly broader than long and widest distal to mid-distance, anter horseshoe-shaped, proximal margin straight with a narrow U-shaped sinus, condyles as long as proximal margin, broader at lateral margins with the slope-angle increasing towards sinus; aperture in ovicellate zooecia distinctly broader than long, more or less semicircular, aperture larger and proximal margin also distinctly wider than in autozooecia, with very narrow, indistinct condyles sloping at a constantly low angle towards sinus. Primary orifice and aperture proximolaterally framed by a smooth narrow band of gymnocystal calcification continuous with the lateral zooecium margin, distolateral border bounded by a broad, raised and curved rim of thick calcification sloping towards orifice and originating from distal basal pore chambers. Oral spines were not observed.

Ooecium initially spherical, becoming semi-immersed by frontal wall of distal zooecium. Complete ooecia during later ontogeny were not preserved, and the nature of frontal calcification therefore not observed, in the available material.

Avicularium situated directly proximolateral to orifice at right or left zooecium margin and without any marginal pores between avicularium and orifice, on a very slightly swollen cystid continuous with the frontal wall, one or two areolar pores situated at proximal end of cystid slightly offset from zooecium margin; in earliest astogenetic zooecia the avicularium is situated near proximal zooid margin, moving distally in later zooecia; rostrum suborbicular or kidney-shaped, usually broader distal to mid-distance, with the broad, smooth and slightly raised rim sloping towards opesium, distolaterally or laterally oriented; mandible setiform, occasionally exceeding twice the length of an autozooecium; crossbar extremely strong and sculptured, slightly arcuate with the apex at centre; distal margin of crossbar (with respect to long axis of rostrum) more or less straight when viewed from above, distinctly broadening and thickening towards the lateral rostrum margin closest to orifice; proximal part of crossbar separated from the proximal margin by a distinct suture, broadening and thickening towards lateral rostrum margin closest to proximal end of zooecium, with a thick semicircular extension protruding from its basal centre.

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

Remarks

At first sight, H. majae is morphologically very closely related to H. hyndmanni due to the thick rim framing the distal orifice and the absence of spines. Yet closer inspection of the aperture and avicularium enables a clear distinction (see Differential diagnosis), demonstrating the importance of SEM for the identification of species in this genus.

Whether any of the specimens cited before as H. hyndmanni from other areas of the Mediterranean Sea (e.g. Harmelin 1969, 1978; d’Hondt 1977) actually belong to H. majae is impossible to determine in the absence of detailed descriptions and illustrations, especially those of the orifice and avicularium. H. hyndmanni of Zabala and Maluquer (1988, p. 129, Figure 292; Plate 15, Figure E) is a different taxon, and is possibly also distinct from H. hyndmanni as defined here (see above), because the avicularium is situated more proximally and its cystid is lacking the areolar pores.

H. majae is reported from the northern (Prvic Island), central (Jabuka Shoal) and southern part of the Adriatic Sea (Lastovo Island; M. Novosel, pers. comm. 2007). The colonies encrust fragments of the erect bryozoans Pentapora fascialis and Adeonella pallasii , and were recovered from 13 to 50 m depths off Croatia.

Figures

Figure 2. Herentia majae n. sp. Holotype, CNHM Inv.br. 30, Adriatic Sea. (A) General aspect of an unbleached colony; note the long avicularian mandibles; (B) autozooecia and ovicellate zooecia; (C) close-up of autozooecium orifice and avicularia; (D) close-up of aperture of ovicellate zooecium; note the different shapes of sinus and condyles compared to orifice of autozooecium; the thickened frontal rim of calcification has not commenced to grow. Scale bars: 200mm (A); 100 mm (B); 50 mm (C, D).