Leucosolenia somesii

Leucosolenia somesii (Bowerbank, 1874)

(Figs 23, 24; Table 9)

Type material: Lectotype BMNH 1925.11.2.24* paralectotype BMNH 1925.11.2.25* slides of the same: BMNH 1956.4.26.35.

Type locality: Brighton Aquarium.

Material studied: One specimen * ZMA Por. 17572 %external morphology * skeleton organization* spicules) %Supporting Information* Table S1).

External morphology: Length up to 12 cm. Cormus formed by dense reticulation of extremely branched* winding tubes % Fig. 23A). Surface hispid. Coloration of living and preserved specimens greyish white. Examined specimen lacks oscular tubes. According to the original description %Bowerbank* 1874)* sponges have numerous small and large oscular tubes* bearing a spicular crown. Oscular tubes erect and slightly curved* gradually narrowing to oscular rim.

Spicules: Diactines % Fig. 24A–C). Two populations of diactines: %i) curved* smooth diactines % Fig. 24A * C)* mean length 424.5 µm* mean width 9.9 µm % Table 9)* slightly curved* smooth* variable in length* lacking lanceolate tips* with undulated tip and %ii) straight* spiny diactines % Fig. 24B * C)* mean length 90.0 µm* mean width 3.3 µm % Table 9)* short* strait* lacking lanceolate tips* with numerous spines in distinct rows % Fig. 24B).

Triactines % Fig. 24D * E). Sagittal* mostly T-shaped* but V-shaped also occur %mean angle 131.7°) % Table 9)* unpaired actines usually shorter then paired actines* but longer* unpaired actines occur rarely %mean length: 127.4 µm—unpaired* 155.2 µm—paired) % Table 9). Paired and unpaired actines equal in width %mean width: 8.2 µm—unpaired* 8.0 µm—paired) % Table 9). Abnormal triactines common* sometimes with undulated rays % Fig. 24E).

Tetractines % Fig. 24F). Quite rare. Sagittal* mostly T-shaped* but V-shaped also occur %mean angle 139.3°) % Table 9)* unpaired actines usually shorter then paired actines* but longer* unpaired actines occur rarely %mean length: 156.0 µm—unpaired* 178.7 µm—paired* 21.5 µm—apical) % Table 9). Apical actines curved and smooth. All actines more or less equal in width %mean width: 9.1 µm—unpaired* 9.5 µm—paired* 10.0 µm— apical) % Table 9).

Skeleton: Very dense net predominantly formed by triactines* oriented in different directions* tetractines rare % Fig. 23B). Both trichoxea populations cover surface of tubes in large numbers* orienting in different directions and making it hispid. Skeleton of osculum was not studied.

Cytology: No material was available for cytological studies.

Distribution: Boreal species. Described from Brighton Aquarium with confirmed reports from the Netherlands %van Soest et al. 2007). Probably it has wider distribution in the North-East Atlantic.

Reproduction: No data on reproduction time are available.

Remarks: Leucosolenia somesii was considered a minor synonym of L. variabilis until a recent study by van Soest et al. %2007) was published. They showed valuable differences between these two species* based on a large number of specimens* including the type material. Here we provide the first molecular data and an updated morphological description. Our novel data confirm that L. somesii represents a distinct species* based on both morphological and molecular analyses. The re-examination of spicules of specimen ZMA Por. 17572 studied by van Soest et al. %2007) confirms the strong correspondence of its specular characteristics to the paralectotype BMNH 1956.4.26.35 % Fig. 23C * D). According to our phylogenetic reconstruction* the most closely related species is Arctic Leucosolenia creepae sp. nov. * with which Leucosolenia somesii shares some specific morphological features: echinate external appearance due to the high number of non-lanceolate diactines protruding to the external surface* and dimensions of tri- and tetractines. The discussion of their differences is given above under the description for Leucosolenia creepae sp. nov .. From all other North Atlantic and Arctic Leucosolenia species * L. somesii differs by the absence of lanceolate diactines.