Latrunculia (Latrunculia) multirotalis Topsent, 1905

Samaai, Toufiek, Gibbons, Mark J. & Kelly, Michelle, 2006, Revision of the genus Latrunculia du Bocage, 1869 Porifera: Demospongiae: Latrunculiidae) with descriptions of new species from New Caledonia and the Northeastern Pacific (, Zootaxa 1127 (1), pp. 1-71 : 36-38

Latrunculia (Latrunculia) multirotalis Topsent, 1905

( Figs 1H, 2 , 4F ; Tables 2 & 3)

Latrunculia multirotalis Topsent 1905: 8 ; Latrunculia multirotalis ; Topsent 1928: 222, PL. VII, FIG. 19.

Holotype material. MNHN L.B.I.M. No D.CL. 1265, spicule slide, W. de Florès (Central Atlantic­ Azores), stn 2210; depth 1229 m.

Description. Small encrusting sponge 2 x 2 x 2 cm diameter. Surface smooth, slightly wrinkled, without distinct openings. Texture unknown. Colour in life unknown; in preservative light brownish olive unknown (after Topsent).

Skeleton. The choanosomal skeleton consists of styles arranged in a wispy polygonalmeshed reticulation ( Fig. 4F ). The ectosomal skeleton consists of a paratangential layer of styles with a palisade of erect anisodiscorhabds on the surface. These are also scattered in the choanosome (after Topsent).

Spicules. The megascleres are smooth, often slightly polytylote styles, centrally thickened, fusiform and straight, 342 (309–364) x 11 (11) m, n=20. Microscleres ( Fig. 1H): anisodiscorhabds are long and hold several spined whorls. The manubrium does not have an expanded, candelabrum­like base, but keeps the form of a straight stem, 6–7 µm thick, armoured with a basal whorl which consists of three horizontal whorls of spines followed by a smooth slender, cylindrical shaft 9 µm long and 7 µm wide. The median whorl is 43–45 µm in diameter and composed of five spines spread out horizontally and divided into three groups, which give eight sets for each of them, and is the largest of the whorls. The subsidiary whorl is slanted upwards. The serrated margins of the median and subsidiary whorls are microspined. The shaft, which thickens between the two discs, fades progressively becoming thinner towards the apical whorl, and having either three, four or even five supplementary subsidiary whorls along the shaft. The apical whorl resembles a small coup edged with teeth and blunt terminally spined cylindrical spines appearing somewhat crown­like. Anisodiscorhabd length, 142 (117–186) µm, n=20.

Substratum, depth range and ecology. Found in on muddy environment at a depth of 1229 m.

Geographic distribution ( Fig. 2 ). Azores

Remarks. One of the key characters that differentiate species within the Latrunculia complex is the development (ontogeny) pattern and structure of the acanthodiscorhabd. As stated above the acanthodiscorhabds of Latrunculia s.s have a straight uniform shaft bearing whorls of crenulated discs ( Carter 1879; Samaai and Kelly 2002; Samaai 2002) and develop from a straight protorhabd as indicated by Dendy, (1917) (see also Samaai and Kelly 2002; Samaai 2002 and Samaai et al. 2003; Samaai et al. 2004). All these characters (based only on the acanthodiscorhabds) are visible in L. multirotalis , suggesting that it is a valid species of Latrunculia . Apart from this it also possesses the basal whorl just above the manubrium as indicative of the subgenus Latrunculia

This species is most distinctive, however, as it differs substantially from other Latrunculia species in the size and structure of the anisodiscorhabds ( Table 3); it possesses multi­crenulated discs along a long shaft. Hinde and Holmes (1892) (PG. 219, FIG. 34, 35) (see also Wiedenmayer, 1994) recorded a fossil anisodiscorhabd with multiple whorls from the Oamaru Diatomite, New Zealand, for a species ( Latrunculia . sp Hinde and Holmes, PG 218, PL. XI, FIG. 35) that occurred during the late Eocene­early Oligocene era. These authors also suggested that this form was a modification of a common plane (two whorls), which ultimately gave rise to the multi­crenulated discs as found in L. multirotalis . The discorhabd structure of the extant Latrunculia multirotalis differs however from the fossil spicule in that the shaft possess multiple spines (as appose to whorls) and in the length of the spicule, which is much larger in size (206 µm) than what is recorded for L. multirotalis . It is difficult to say whether the fossil acanthodiscorhabds are homologous to that found in the extant species, but it does suggest that several species of “latrunculids” must have coexisted at the source of this assemblage (See also Wiedenmayer 1994).

The species L. multirotalis was only ever recorded from the North Atlantic off Azores ( Table 2) .

Figures

FIGURE 2. Worldwide distributions of Latrunculia (Latrunculia) species. Distributions of 1) Latrunculia cratera du Bocage, 2) L. bocagei Ridley and Dendy, 3) L. apicalis Ridley and Dendy, 4) L. biformis Kirkpatrick, 5) Latrunculia basilis Kirkpatrick, 6) L. brevis Ridley and Dendy, 7) Latrunculia palmata Lévi, 8) Latrunculia multirotalis Topsent, 9) Latrunculia crenulata Lévi, 10) Latrunculia ikematsui Tanita, 11) Latrunculia oxydiscorhabda Alvarez et al., 12) Latrunculia triverticillata Alvarez et al., 13) Latrunculia fiordensis Alvarez et al., 14) Latrunculia novaecaledoniae sp. nov.

FIGURE 4. Photomicrographs of choanosomal architectures: A. L. bocagei Ridley and Dendy 1886; B. Latrunculia apicalis Ridley and Dendy 1886; C. Latrunculia biformis Kirkpatrick 1908; D. Latrunculia basilis Kirkpatrick 1908; E. Latrunculia brevis Ridley and Dendy 1887; F. Latrunculia multirotalis Topsent 1905.