Hamacantha (Zygherpe) desmacelloides Hajdu, Hooker & Willenz, 2015, sp. nov.
Creators: name: Hajdu, Eduardo
name: Hooker, Yuri
name: Willenz, Philippe
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Poecilosclerida
Hamacanthidae
Hamacantha
Hamacantha desmacelloides

description: Hamacantha (Zygherpe) desmacelloides sp. nov.
Figs 2 A, 3, Table 1
Holotype. CZA 13661 (fragments from holotype MNRJ 13661, RBINS 13661, MHNG INVE 76156), Parachique (05°47’35.30’’ S – 80°57’08.70’’ W), Bahía de Secchura, Peru, 7.4 m depth, coll. Y. Hooker, 07.xii.2009.
Paratypes. CZA 11342 (fragments MNRJ 11342, RBINS 11342, MHNG INVE 76155), Bahia Ladron (06°56’0.59’’ S – 80°42’58.7’’ W), Islas Lobos de Afuera, Peru, 11.1 m depth, coll. Ph. Willenz & Y. Hooker, 04.x.2007. CZA 12167 (fragments MNRJ 12167, RBINS 12167, MHNG INVE 76162), small cove to the north of Quilca (16°42’06.10’’ S – 72°26’54.0’’ W), Peru, 2.6 m depth, coll. Y. Hooker & M. Vilchez, 01.xii.2008. CZA 13690 (fragments MNRJ 13690, RBINS 13690, MHNG INVE 76157), Bajo Norte I (05° 12' 02.80" S – 81° 12' 31.30" W), Isla Foca, Peru, 13.9 m depth, coll. Y. Hooker & M. Rios, 11.xii.2009. CZA 13699 (fragments MNRJ 13699, RBINS 13699, MHNG INVE 76158), Bajo Norte II (05°12’06.08’’ S – 81°12’29.70’’ W), Isla Foca, Peru, 9.1 m depth, coll. Y. Hooker & M. Rios, 13.xii.2009.
Additional material. CZA 14501 (fragments MNRJ 14501, RBINS 14501), Islote Norte, Islas Lobos de Tierra, Peru, 8 m depth, coll. Y. Hooker & A. Gonzales, 14.ix.2010.
Diagnosis. This is the only encrusting Hamacantha with tylostyles, cyrtancistra-like diancistras and two categories of sigmas, both apically microspined.
Description (Fig 2 A). The holotype covered over 10 x 5 cm in area, and now consists of two small fragments, the largest of which has 25 mm in maximum diameter and 2–3 mm maximum thickness. It is the thickest specimen found, all the remaining ones were no thicker than 1 mm, and were encrusting on rocky surfaces. The largest one, CZA 11342 covered ca. 15 x 7 cm in area. The sponge is light-yellow alive, and becomes beige in ethanol. A clear ectosomal reticulation is visible in the in situ photos of CZA 12167, and subectosomal canals were visible in CZA 12167, 13661 and 13699, but less obvious in CZA 11342. The consistency is fragile and the texture mostly reflects the underlying substratum.
Tylostyles Diancistras Sigmas H. (Z.) desmacelloides sp. nov.
Skeleton (Figs. 3 A–D). Ectosomal architecture (Fig. 3 A) with a loose reticulation of tylostyles, either single or in paucispicular tracts. Pores (31–56 µm diameter) are seen in the meshes, and microscleres are abundant. Diancistras are mostly arranged in loose rosettes. Choanosomal architecture (Figs 3 B–C) consists of short, sinuous, wispy longitudinal paucispicular tracts of tylostyles supporting the tangential ectosomal architecture. Scattered megascleres are common, as well as diancistras, the latter frequently disposed in rosettes around the longitudinal tracts (Figs 3 C–D). The choanosomal framework arises from a discontinuous and variably thick tangential basal layer of megascleres and diancinstras.
Spicules (Figs 3 E–Y’, Table 1).
Megascleres. Tylostyles (Figs 3 E–P), smooth, slender, mostly slightly curved with well pronounced heads, 138–511 / 5–13 Μm. Variations are straight shafted and subtylostylote forms, the latter with elliptical, sub-terminal heads. Microscleres. Diancistras (Figs 3 Q–S), cyrtancistra-like, large, smooth, never notched, fimbriae restricted to the inner surfaces of hooks, which may project slightly off the plane of the main shaft, 104–219 Μm. Sigmas I (Figs T–V’), relatively stout, mostly contorted, apically microspined, 18–26 Μm. Sigmas II (Figs W–Y’), relatively stout, mostly contorted, microspined on both apical thirds or fourths, 8–16 Μm.
Distribution and ecology. The species was recorded between 2.6 and 13.9 m depth, and its distribution range stretches from 05º12’ to 16º42’ S. Water temperature in the collecting sites ranged from 13 to 21°C. The following species were observed in the underwater images obtained from the studied specimens: barnacles, brachiopods, bryozoans, ophiuroids, polychaetes, shrimps, and other sponges.
Etymology. The species name “ desmacelloides ” recognizes its similarity to some Desmacella spp., where the combination of tylostylote megascleres and sigma microscleres is a recurrent occurrence.
Remarks. The diancistras in the new species resemble the cyrtancistras of Pozziella (Hajdu, 1994; Díaz- Agras, 2008). We preferred to restrict the use of the term cyrtancistra to the gigantic sigmoid microscleres of the latter genus(103–760 Μm long), which are most often of considerably hemispherical morphology, were not yet reported to form rosettes, and come next to exotyles. These are generally larger than the megascleres co-occurring in the same species, which is not the case in the new species described here, nor on additional Hamacantha spp. with somewhat similar diancistra morphology [e.g. H. popana (de Laubenfels, 1935)].
The only other Hamacantha known to possess tylostyles and an encrusting habit, H. hyaloderma (see below), can be easily differentiated from the new species through the latter’s possession of cyrtancistra-like diancistras which are over three times larger and of a different morphology, as well as two categories of apically microspined sigmas, in contrast to two or three smooth categories in H. hyaloderma. All other species of Hamacantha have either diactinal or styloid monactinal megascleres, when sigmas are present, these were not reported to be apically microscpined, and in general they are not thinly encrusting. The new species appears to us well differentiated from all Hamacantha spp.
description: Published as part of Hajdu, Eduardo, Hooker, Yuri & Willenz, Philippe, 2015, New Hamacantha from Peru and resurrection of Zygherpe as subgenus (Demospongiae, Poecilosclerida, Hamacanthidae), pp. 87-99 in Zootaxa 3926 (1) on pages 89-93, DOI: 10.11646/zootaxa.3926.1.3, http://zenodo.org/record/288028