Rhaphidhistia belizensis Rützler, Piantoni, Van & Díaz, 2014, new species
Creators: name: Rützler, Klaus
name: Piantoni, Carla
name: Van, Rob W. M.
name: Díaz, Cristina
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Hadromerida
Trachycladidae
Rhaphidhistia
Rhaphidhistia belizensis

description: Rhaphidhistia belizensis new species
(Figures 3 g, 29)
Material. Holotype: USNM 1228992, Carrie Bow Cay forereef slope, coral rock underside, 30 m; K. Ruetzler col. 26 Apr 1974.
Paratypes: USNM 1228993, 1228994, Curlew Cay, frame-work cave in forereef wall (1.5 m from entrance), 20 m; C. Piantoni and M. Parrish col. 22 Aug 2012. USNM 1228995, Curlew Cay, frame-work cave in forereef wall (1.5 m from entrance), 20 m; C. Piantoni and M. Parrish col. 23 Aug 2012.
Diagnosis. Thinly encrusting, orange-colored Rhaphidhistia with large oxeas (247–860 x 5–18 µm) and three size classes of spirasters (28– 48 x 8–15 µm; 23– 35 x 4–6; 7– 18 x 3–9 µm) spread densely throughout the body. Largest spirasters with straight shaft and regularly spaced spiral spination by equal-sized rays (spinispires); smallest are microspined.
External morphology. Very thin (0.5–2 mm) crusts mirroring the structure of the coral substratum, covering 2–50 cm 2. Groups of tiny pores but no obvious distinctions of oscula or ostia. Surface smooth, consistency firm, color vivid orange to light orange red.
Skeleton structure. Oxeas without much orientation (criss-cross), a few in the choanosome in ill-defined tracts, some in the ectosome parallel to the surface. Spirasters occur in abundance throughout the tissue.
Spicules. Oxeas, straight or slightly bent, thickest in the center of the shaft, gradually tapering to sharp points; a few show styloid or strongylote modifications: 247–860 x 5–18 (535 x 12) Μm; spirasters I, straight shafts (averaging 30 % of total spicule width) surrounded by a regular spiral of equal-sized rays: 28– 48 x 8–15 (39 x 12) Μm; spirasters II, short and thin and less regular in spination than spirasters I: 23– 35 x 4–6 (29 x 5) µm; spirasters III, microspined or rugose: 7– 18 x 3–9 (12 x 6) Μm.
Ecology. Under forereef coral rock and in caves, 20– 30 m.
Distribution. Belize (Caribbean).
Etymology. Named after Belize, the Caribbean nation where it was first discovered.
Comments. Morphological properties of our species agree well with the redescription of the type species of Rhaphidhistia, R. spectabilis Carter, 1879 (Hooper & van Soest, 2002, fig. 3A–C), particularly the thinly encrusting habit, disorganized arrangement of oxeas, abundance of spirasters throughout, and mostly straight and very regular spirasters (spinispirae). The main differences are the fewer twists of spines (up to six versus up to ten) and the second, smaller size class of spirasters in our material, and of course the geographical separation Belize versus Mauritius.
In course of writing this chapter, colleagues from Colombia introduced a new species of Rhaphidhistia, R. guajiraensis, discovered in 50 m on a soft bottom off Dibulla, Colombian Caribbean (Díaz & Zea, 2013). This species is similar to ours but is thickly encrusting, as well as incorporating and agglutinating substratum particles (color in life is not known), and, like the type species (R. spectabilis), it lacks a small class of microspined spirasters (as was confirmed by S. Zea, personal communication).
description: Published as part of Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014, Diversity of sponges (Porifera) from cryptic habitats on the Belize barrier reef near Carrie Bow Cay, pp. 1-129 in Zootaxa 3805 (1) on pages 51-53, DOI: 10.11646/zootaxa.3805.1.1, http://zenodo.org/record/249983