Distansescharella alcicornis ( Jullien, 1882 )

Souto, Javier, Berning, Björn & Ostrovsky, Andrew N., 2016, Systematics and diversity of deep-water Cheilostomata (Bryozoa) from Galicia Bank (NE Atlantic), Zootaxa 4067 (4), pp. 401-459 : 419-421

Distansescharella alcicornis ( Jullien, 1882)

( Figs 39–45 , Table 9 )

Cribrilina alcicornis Jullien, 1882: 12 , pl. 14, figs 23–25; d'Hondt 1973: 378, pl. 3A, B; Harmelin 1978: 178, text-figs 3, 4, pl. 1, fig. 3; Harmelin & d'Hondt 1992: 28 (listed).

Cribrilaria alcicornis: Hayward & Ryland 1978: 146 (listed); Hayward 1979: 60 (listed).

" Cribrilina " alcicornis: Harmelin et al. 1989 : pl. 1, figs 5, 6.

Not Distansescharella alcicornis : López-Fé 2006: 1807 , figs 7, 8.

Material examined. Lectotype (designated here): MNHN 3736, Cribrilina alcicornis Jullien 1882 , NW de l’Espagne, Travailleur, 14 June 1881, 1068 m; Coll. Calvet, nº383 ‘type’. Paralectotype (designated here): MNHN 3787, Cribrilina alcicornis, Travailleur , 13 June 1881, station Dr. 1 (1ª ser.), 2018 m, Coll. Calvet, nº 56 ‘type’ (colony in poor condition). Other material from Galicia Bank: MNCN 25.03/3938, 3939, 3940, locality DR09; OLL 2015/898, 899, locality V01. Other material examined: MNHN 19796, Cribrilaria alcicornis , BALGIM DR 153, 568 m, 27 June 1984; MNHN 18351, Cribrilaria alcicornis, Th. 71, X348, 44º7.5’ N 4º43.6’ W, 600–900 m, 16 October 1971; MNHN 18362, Cribrilaria alcicornis, Th. 71, X348; MNHN 7024, Cribrilaria alcicornis (Reverter, IV-98), X359, 17 October 1971, 605– 650 m, 44º07.2’ N 04º49.4’ W; MNHN 7102, Cribrilina alcicornis, Th W 423, 11 October 1970, 710– 1070 m, 44º3.7’ N, 07º07.5’ W; MNHN 7185, Cribrilina alcicornis Thalassa, Y 395; MNHN 7197, Cribrilaria alcicornis , Y 410, 360 m, 40º34.4’ N 09º22.1’ W; MNHN 6983, Cribrilina alcicornis var. bifurcata , type var., st. X313.

SD, standard deviation; N, number of measurements.

Description. Colonies encrusting, unilaminar, multiserial, forming spots or small patches. Zooids oval, separated by deep grooves; costate frontal shield flattened, surface smooth with growth striations; shield comprising 16–19 broad flattened costae with up to 5 intercostal spaces, round in central part and elongated at periphery; distalmost pair of costae usually broader than others, both distal costae with distal projection centrally that forms short but broad central denticle with straight distal margin; gymnocystal walls relatively well developed, especially in proximal region. Zooidal orifice D-shaped, distinctly wider than long, distal margin with 4 thick jointed oral spines in ovicellate and non-ovicellate autozooids, forming a kind of collar around orifice with slightly wider gap between bases of distal pair; spines reminiscent of elk horns, slightly tilted, closely spaced and sometimes almost touching each other; either relatively small with 3–4 tines, or large with 4–5 flattened triangular tines, forming a broad ‘elk horn’, to which species name alludes.

Ovicells hyperstomial, cleithral. Bilobate ooecium produced by distal autozooid and positioned on its proximal gymnocyst; globular, usually longer than wide, with prominent suture along entire midline; ectooecium smooth with growth striations, proximal margin incorporating bases of distal pair of oral spines.

Avicularia interzooidal, small, with irregular cystid outline, only slightly longer than wide, usually 2 per zooid, situated lateral to zooidal orifice, mandibles directed laterally to distally; gymnocystal lateral walls well developed, particularly extensive proximolaterally; avicularium pyriform frontally, framed by elevated rim, rostrum at acute angle to colony surface; palatal foramen and postmandibular opesia united in one opening, oval and subelliptical to pyriform, surrounded by smooth cryptocyst that is broadest proximally and narrowing distally; palatal opesia separated from postmandibular area by very small indentations (condyles) on which mandible is hinged.

Kenozooids common, irregular in shape, relatively large, sometimes almost attaining length and width of autozooid; frontal area flattened or slightly convex, almost entirely composed of smooth gymnocyst apart from round to oval membranous window with slightly elevated rim usually situated in centre of kenozooid; oval opesia of variable size, surrounded by narrow smooth cryptocyst that in some cases closes opesia almost completely. Basal pore-chambers present in all types of zooids.

Ancestrula not seen.

Remarks. This species was originally described by Jullien (1882) as Cribrilina alcicornis , collected from two stations on the northern Iberian continental slope close to Galicia Bank at 1068 and 2018 m depth. The systematic position of C. alcicornis was clarified by López-Fé (2006), who formally assigned it to the genus Distansescharella following a suggestion of Harmelin et al. (1989) and a review of the genus Cribrilina by Bishop (1986, 1994). The specimens from the Canary Islands reported by López-Fé (2006) as D. alcicornis , however, obviously do not belong to this species (see Remarks on Distansescharella cervicornis n. sp. below). In contrast, the specimens collected from Galicia Bank are indistinguishable from the type specimens of D. alcicornis described by Jullien ( Figs 39–41 ).

The species has also been reported from the Bay of Biscay (d’Hondt 1974), the Strait of Gibraltar ( Harmelin 1978), NW Iberia ( Harmelin 1978; Reverter-Gil & Fernández-Pulpeiro 2001) and the continental slope of Portugal ( Reverter-Gil et al. 2014) between 450 and 2018 m depth. Most of these data need to be revised, however, before a decision on their conspecificity can be made.

On Galicia Bank, D. alcicornis was recorded at almost all localities on coral, rocks, and shells from 765 to 1697 m depth.

Figures

FIGURES 39 – 45. Distansescharella alcicornis: 39 – 41, lectotype (MNHN 3736): 39, general view of colony; 40, autozooid with oral spines; 41, distal part of autozooid with ovicell and avicularia. 42 - 45, specimens from Galicia Bank: 42, parts of colony with ovicellate zooids (OLL 2015 / 898); 43, autozooids with avicularia (MNCN 25.03 / 3938), 44, part of colony with two large kenozooids (MNCN 25.03 / 3938); 45, autozooid with ooecium and two proximal oral spines (OLL 2015 / 898).

Tables

TABLE 9. Measurements (in mm) of Distansescharella alcicornis.

	Mean	SD	Minimum	Maximum	N
Autozooid length	0.482	0.0416	0.391	0.555	24
Autozooid width	0.322	0.0297	0.270	0.378	24
Ooecium length	0.086	0.0075	0.075	0.100	24
Ooecium width	0.128	0.0092	0.115	0.151	24
Ovicell length	0.194	0.0130	0.170	0.209	7
Ovicell width	0.173	0.0106	0.156	0.183	7
Avicularium cystid length	0.106	0.0137	0.082	0.132	26
Avicularium cystid width	0.082	0.0122	0.064	0.115	26
Avicularium frontal area length	0.067	0.0051	0.058	0.076	26
Avicularium frontal area width	0.045	0.0056	0.034	0.055	26