Paraleucilla dalmatica Klautau, Imešek, Azevedo, Pleše, Nikolić & Ćetković, 2016, sp. nov.

Paraleucilla dalmatica sp. nov.

urn:lsid:zoobank.org:act: D066F56A-1FD7-4742-98E2-2CEE390D1E21

Figs 12–13; Table 10

Etymology

From the type locality. Dalmatia is one of the four historical regions of Croatia.

Material examined

Holotype

ADRIATIC SEA: near the Island of Čiovo, 43°29'02.0" N, 16°22'10.9" E, 5 m, collected by B. Pleše and V. Nikolić, 5 Nov. 2010 (IRB-SD5 = UFRJPOR 8346, in ethanol).

Paratype

ADRIATIC SEA: same data as holotype (PMR-13747, in ethanol).

Colour

Beige or light brown in life and white in ethanol.

Description

The body has the shape of a vase with a single apical osculum surrounded by a crown of trichoxeas (Fig. 12A). Surface is very hispid. The aquiferous system is leuconoid (Fig. 12B). The cortical skeleton is composed of the basal system of large tangential tetractines and few triactines (Fig. 12C). Giant diactines cross the surface, penetrating deeply into the choanosome. They are present from the osculum to the base of the sponge. Among these giant diactines there are also very thin and long trichoxeas, organised in tufts, and very few microdiactines (Fig. 12D). The choanosomal skeleton is characteristic of Paraleucilla, with an inarticulate region (outer region) and a zone without organisation (inner region) (Fig. 12E). The outer region is formed by the apical actine of the cortical tetractines, the unpaired actine of subatrial tetractines and very few triactines. The paired actines of these subatrial spicules are frequently curved, resembling a hook. The inner region is formed by scattered subatrial tetractines and very few triactines. The atrial skeleton is composed of tetractines only (Fig. 12F). In some parts of the sponge the inarticulate skeleton seems not to exist and it becomes more similar to Leucandrilla.

Spicules (Table 10)

OSCULAR TRIACTINES. Strongly sagittal. Actines are conical and sharp. The unpaired actine is longer and thinner than the paired ones and basipetally directed.

DIACTINES. Giant. They are present in the oscular crown and cortex. They are almost fusiform but slightly curved, with a thicker tip outside the sponge (Fig. 13A). The size is very variable. Many diatoms are attached to the diactines surrounding the osculum. Size: 1000.0/25.0–50.0 µm.

TRICHOXEAS. Present in the oscular crown and cortex. They are thin, straight and most of them are broken. Size:> 330.0/2.5–5.0 µm.

MICRODIACTINES. Very rare, fusiform or arrow-headed. Sometimes one of the tips has small spines while the other one is thicker (Fig. 13B). They are present in the cortex. Size: 95.0/ 2.5 µm.

CORTICAL TETRACTINES. Sagittal. Actines are conical with sharp tips. The apical actine is longer than the basal ones, conical, straight and sharp (Fig. 13 C–D). Size: 159.1/ 13.4 µm (paired actine); 133.1/ 13.4 µm (apical actine).

CORTICAL TRIACTINES. There are very few, subregular to regular. Actines are slightly conical with sharp tips (Fig. 13E). Size: 142.8/ 12.4 µm (paired actine); 149.3/ 12.9 µm (unpaired actine).

SUBATRIAL TRIACTINES AND TETRACTINES. The triactines are rare. Actines are conical and sharp. The unpaired actine is longer than the paired ones. The paired actines are frequently strongly curved. One of them is often shorter than the other. The apical actine of the tetractines is very short, thin, smooth and strongly curved (Fig. 13 F–K). Size: 180.0/ 13.2 µm (paired actine); 205.8/ 12.7 µm (unpaired actine); 37.8/ 8.8 µm (apical actine).

ATRIAL TETRACTINES. Sagittal. Actines are slightly conical and sharp. The apical actine is slightly conical, smooth, thinner than the basal ones and straight or only slightly curved (Fig. 13 L–M). Size: 157.9/ 10.5 µm (paired actine); 157.0/ 11.4 µm (unpaired actine); 115.7/ 7.3 µm (apical actine).

Ecology

Specimens were collected on a cliff in a shaded area.

Remarks

Currently there are 11 known species of Paraleucilla, and P. magna Klautau et al., 2004 is the only one that has been recorded in the Mediterranean Sea up to now. Both the external morphology and spicule composition differ in these two species. The most similar species to P. dalmatica sp. nov. are P. perlucida Azevedo & Klautau, 2007, from Brazil, and P. princeps (Row & Hôzawa, 1931), from Australia. Nonetheless, P. dalmatica sp. nov. can be differentiated from P. perlucida mainly by the absence of diactine I and trichoxea in the latter. Paraleucilla princeps also differs by the absence of diactine I and microdiactines. Therefore, P. dalmatica sp. nov. is the second species of Paraleucilla recorded from the Mediterranean Sea.