Clathria (Thalysias) venosa ( Alcolado, 1984 )

Gómez, Patricia, 2014, The genus Clathria from the Gulf of Mexico and Mexican Caribbean, with redescription and resurrection of Clathria carteri (Poecilosclerida: Microcionidae), Zootaxa 3790 (1), pp. 51-85 : 70-74

Clathria (Thalysias) venosa ( Alcolado, 1984)

( Fig. 15 –16, 20E, Tab. 5 )

Microciona venosa Alcolado, 1984:6 .

Clathria (Thalysias) venosa sensu Hooper 1996:411 , Díaz 2005:471, Gómez 2007:58, Hajdu et al. 2011:136.

Specimen Location Style I Style II Style III Acanthostyle

1 1–3 3– 5 n.r. 2–5 FIGURE 16. SEM depiction of spicules from Clathria (Thalysias) venosa ( Alcolado, 1984) : A-B. Auxiliary subtylostyles. A1- B1. Detail of microspined head of auxiliary subtylostyles. C. Main subtylostyles. C1. Detail of main subtylostyle head. D. Palmate isochelae. E. Acanthostyles. F. General view of spiculation. G-H. Toxas I and II. I. Rhaphidiform toxa. Scale bars: A, B, 50 µm; C, 30 µm; A1, B1, C1, 15 µm; D, 5 µm; E, 15 µm; F, I, 50 µm; G, H, 5 µm.

Material examined. CNPGG –704 Santiaguillo, Veracruz, 19º9’N 95º49’W, 31/VIII/2003 reef bottom, 25 m. CNPGG –1448 Anegada de Adentro Veracruz 19º13’17.2”N 96º03’23.1”W, 27/XI/2012. CNPGG –1452 Blanquilla reef Veracruz 19º12’10.72”N 96º04’18.58”W, 20/V/2011.

Description. This is a thin incrustation over rock 6–9 × 3.8 cm 2, 1– 3 mm thick. Light grey in vivo, creamy white in spirit, consistency soft, slimy. Surface smooth with a canal system seen through the dermis, characterized by a bulged stellate pattern with oscules round and centered, 4 mm in diameter ( Fig. 15 A); all of which contract when out of water. The dermis is detachable when touched.

Skeleton. The ectosomal consists here and there of ill-defined bouquets of auxiliary subtylostyles, slightly protruding from the surface; obscured by many other subtylostyles tangentially displayed and others in vague tracts. The choanosomal skeleton consists of a basal plate from which arise vague, straight, and sinuous tracts sometimes just simulating a bundle of spicules aligned in any direction ( Fig. 15 B–C); the basal plate is combined also with a leptoclathriid arrangement of singly thick subtylostyles and acanthostyles with their heads fixed to the basal plate, points directed upwards.

Spicules. Thin auxiliary subtylostyles with smooth and microspined heads in two size categories: I, 80–205 × 1.5–3.7 µm; II, 243.7–377 × 3–6 µm. Thick subtylostyles with a slight constriction at the neck, rugose heads or sometimes smooth; there are few of these in the field 127.4–317 × 5–10.4 µm; acanthostyles spined all over 47–68.1 × 3.6–5 µm; palmate isochelae 4.4–12 µm; two or perhaps three categories of toxas: I, 5.2–15.6 µm; toxa II in low numbers, 34.5–57.2 µm; and rhaphidiform or accolada toxa, 87–468 µm (Fig. 16A–I, Measurements in Tab. 5 ).

Remarks. The present material more likely refers to C. (T.) venosa than to C. (T.) raraechelae van Soest, 1984; the two species are similar in their external morphology, incrusting with vein-like appearance of the canal system, and spicule types. Nevertheless they differ from each other in that C. (T.) venosa has irregular and ill-defined spicule tracts together with a leptoclathriid skeleton, in contrast to the more elaborated spongin reticulation of C. (T.) raraechelae . Moreover, there are clear differences in spicule geometry: C. (T.) raraechelae has smooth heads on both styles and subtylostyles, has rare or absent isochelae and its toxas as well are rare but with a smaller size range (48–152 µm) than in C. (T.) venosa . Finally, a bright red color underneath the ectosome of C. (T.) raraechelae is an additional indication that they are different species.

A spicule type not cited in the original description is the presence of a thick style but these spicules are scarce in the field and thinner compared with those in the other Clathria species here presented.

Clathria (T.) venosa seems to be an opportunistic species, being more abundant in disturbed environments and exposed to organic matter ( Alcolado 1987; Hadju et al. 2011), as was the present material, which was only found in certain locations off the Harbor of Veracruz, and apparently so is Alcolado's sample from the dock basin of La Havana City, places suggesting some degree of organic pollution.

Distribution. It has been recorded once in Veracruz, Mexico 8 m depth ( Gómez 2007); Cuba 1 m depth, Brasil 3–4 m depth, Panama. From mangrove and reef habitat.

Figures

FIGURE 15. Clathria (Thalysias) venosa (Alcolado, 1984): A. Specimen in situ. B-C. Skeleton structure in tranverse section. Scale bars: A, 1 cm; B, 70 µm; C, 500 µm.

Tables

TABLE 5. Comparison data of spicule micrometries, distribution / depth (in meters) of Clathria (Thalysias) venosa (Alcolado, 1984). Measurements are in µm, mean values are in bold, measurement number n = 30. Ver, Veracruz; n. r., not recorded (* from literature).

CNPGG	Ver/	80– 136.3 –205/	243.7– 324.6 –377/	127.4– 201 –317/	47– 56.8 –68.1/
704	25	1.5– 2.2 –3.7	3– 4.7 –6	5– 7.7 –10.4	3.6– 4.4 –5
Alcolado, 1984*	Cuba/	60–155/	230–350/	n.r.	40–65/