Latrunculia (Latrunculia) basilis Kirkpatrick. We 1908

Latrunculia (Latrunculia) basilis Kirkpatrick, 1908

(Figs 1E, 2, 4D; Tables 2 & 3)

Latrunculia apicalis var. basilis Kirkpatrick, 1908: 57; Latrunculia antarctica Tanita, 1959, P.7, FIG 7, 8; Latrunculia lendenfeldi; Koltun, 1964, pg. 23; Latrunculia brevis; Uriz, 1988, pg. 49, FIG. 25. Latrunculia lendenfeldi Hentschel, 1914, PG. 44, PL. V, FIG. 1

Holotype material. BMNH 1908.2.5.72, labeled Latrunculia apicalis var. basilis identified by Kirkpatrick, 1908, ethanol preserved sample (light brown­beige subsample of specimen, 10 x 10 x 2 mm in diameter) and microscope­slides, dredged off Balleney Island, Antarctic; depth 462 m, National Antarctic expedition, HMN Discovery 1901­04.

Other material examined. ZMB 4812 (holotype), Labeled Latrunculia lendenfeldi Hentschel, 1914, seven microscope­slides, Wilhelm II Coast, Antarctica, 66º 2' 9''S; 89º 38'E, depth 385 m

Description. Small encrusting sponge, 30 x 20 x 6 mm diameter. Surface smooth, but sandpapery with one volcano­shaped or conical osculum at the apex (recorded by Kirkpatrick), but not visible in the preserved type specimen, and mammiform areolate porefields 0.5 x 0.5 mm in diameter. Ectosome thin and transparent, easily separable from underlying choanosome. Colour in life light brown; in preservative light beige­brown.

Skeleton. The choanosomal skeleton is a loose irregular polygonal­meshed reticulation formed by wispy tracts of smooth styles (Fig. 4D). These tracts range in width from 45–100 µm in thickness, forming meshes that are 273 µm wide. There is no distinction between the primary and secondary fibres. Towards the surface the spicules tend to be vertically arranged. The surface of the ectosome is lined with an erect layer of single anisodiscorhabds. Beneath the discorhabds in the ectosome is a thin paratangential layer of densely interlocking megascleres, approximately 227 µm wide.

Spicules. Megascleres: styles are smooth, centrally thickened, fusiform and slightly sinuous, resembling strongyloxeas in appearance 554 (500–592) x 16 (16) m, n=20. Microscleres (Fig. 1E): leafy anisodiscorhabds, the manubrium is a vertically arranged spinose base armoured with a basal whorl with two short horizontally arranged whorls of spines followed by a smooth slender shaft 11 m long and 7 m wide. The median whorl is circular, broad, flat, and horizontally arranged, 48 m in diameter, larger in diameter than the subsidiary and apical whorls. The median whorl is divided into four distinct segments each possessing eight denticulate margins or spines. The subsidiary whorl is slanted upwards and situated closer to the apical whorl. The subsidiary whorl is divided into three cup­shaped segments fused with seven to eight denticulate margins. The spines of the apical whorl are the smallest, convex and slanted upwards to end in a trident­like tuft of acute spined projections. Anisodiscorhabd length, 69 m, n=20.

Substratum, depth range, and ecology. Substrate and ecology unknown with a depth range from 81– 700 m.

Geographic distribution (Fig. 2). Balleney Island, Cape Cook and Oates coast, Antarctica; Falklands Islands; Namibia.

Remarks. Kirkpatrick (1908) described this specimen as a variant of Latrunculia apicalis. As he was clear in stating the subspecific rank of this specimen ("var."), the name basilis under article 45g, 46b and 72a of the ICZN is elevated to species status and will subsequently be referred to as L. basilis. In his description Kirkpatrick (1908) states that the anisodiscorhabds vary somewhat from the typical form (as for Latrunculia brevis) (62 m in length) having a small spike at the base, and a still smaller one at the apex. Upon examination of the type species no basal or apical spike were observed, but this appearance is due to the angle the discorhabds was observed due to the vertical arrangement of the expanded spinose base of the manubrium. The small spike on the apical whorl is that of the vertical arrangement of the crown. On close examination the morphology of the discorhabd closely resembles that of L. bocagei, but differs from the anisodiscorhabd of L. bocagei in having apical spines as opposed to the spined conules. The specimen collected on the Soviet Antarctic Expedition (Type data unknown­no collection data on label, but examined) and identified by Koltun as a species of L. lendenfeldi, is considered a specimen on L. basilis, base on the anisodiscorhabd morphology, apical structures, spicule measurements and locality (specimen examined by authors) (see Tables 2 and 3). The specimen of L. brevis identified by Uriz (1988) from Namibia (not examined by authors) is considered a specimen of L. basilis based solely on the geometry and structure of the anisodiscorhabd and structure of the styles, which resembles strongyloxeas in appearance (Table 3).

Although Tanita's type specimen was not examined [Latrunculia antarctica (holotype whereabouts unknown­Hooper and Wiedenmayer 1994)] the similarities in morphology and spiculation (see Table 3) as well as the specimens geographic position (Table 2) strongly suggest that it is the same as Latrunculia basilis from Balleney Island in the Ross Sea, Antarctica. L. lendenfeldi Hentschel (1914), after examination of the type species (ZMB 4812) (see FIG 12 C in Alvarez et al. 2002), is not a valid species but conspecific with L. basilis and therefore a synonym of the latter species. This validation is based on the gross morphology, apical structure and spicule length (see Table 2) of the anisodiscorhabd morphology and the locality of the species (see Table 3) (specimen examined by authors). Based on these similarities in spiculation the authors consider L. antarctica (sensu Tanita 1959), L. brevis (sensu Uriz 1988), L. lendenfeldi (sensu Koltun 1959) and the type species of L. lendenfeldi Hentschel (1914) as synonyms of L. basilis Kirkpatrick. We consider that the morphology and ornamentation of the discorhabd is stable within any given sample and justifies species distinction.