Agelas schmidti Wilson, 1902

Parra-Velandia, Fernando J., Zea, Sven & Van Soest, Rob W. M., 2014, Reef sponges of the genus Agelas (Porifera: Demospongiae) from the Greater Caribbean, Zootaxa 3794 (3), pp. 301-343 : 329-331

Agelas schmidti Wilson, 1902

Fig. 12

The species was named to honour Oscar Schmidt, a German spongologist.

Agelas schmidti Wilson, 1902: 398 ; Hechtel 1969: 17; van Soest & Stentoft 1988: 102, Fig. 50; Lehnert & van Soest 1998: 81; Lehnert & van Soest 1999: 156; Alcolado 2002: 61 (in part); Muricy & Hajdu 2006: 116; Mothes et al. 2007: 86; Zea et al. 2009; Alcolado & Busutil 2012: 69.

? Agelas schmidti ; Wintermann-Kilian & Kilian 1984: 132; Muricy et al. 2011: 39.

[Non: Agelas schmidti ; Wiedenmayer 1977: 130, Fig. 137, pl. 27, Fig. 1 ; Zea 1987: 210, Fig. 76, Pl. 12, Fig. 9 ; Gammill 1997: 43, Fig. 42; Erpenbeck et al. 2007: 1564; Muricy et al. 2008: 82, figs; Rützler et al. 2009: 302 (= A. wiedenmayeri )].

Agelas sventres ; Valderrama 2001: 51, Fig. 17.

[Non: Agelas sventres Lehnert & van Soest 1996 (a valid species)].

Material and distribution. Holotype not examined (but see remarks), deposited at National Museum of Natural History ( USNM 7683) collected on 1899 at Saint Thomas, U.S. Virgin Islands, depth 37– 42 m. The material reviewed here includes specimens from (but is not restricted to) the Bahamas (INV– POR 936), Belize (INV– POR 956), Rosario Islands (INV– POR 961), Jamaica (INV– POR 1000), Morrocoy ( Venezuela, INV– POR 1197), Santa Marta (INV– POR 872), and Gulf of Urabá (INV– POR 539, see Valderrama, 2001).

Previous works have reported the species also from Bahamas and Florida Keys (Zea et al. 2009), Cuba ( Alcolado 2002), Dominican Republic ( Weil 2006), Jamaica (Lehnert & van Soest 1998; 1999), Guadeloupe ( Alcolado & Busutil 2012), Barbados ( Hechtel 1969; van Soest & Stentoft 1988), and Brazil ( Mothes et al. 2007). The authors observed but did not collect this species in the west of San Andres Island hanging under rocks in shallow waters, and in Bocas del Toro, Panama. From the above, we consider A. schmidti a tropical northwestern Atlantic species (but see remarks). Our specimens were found from 1 to 38 m in depth, abundant at 15– 21 m.

Description. This species typically forms repent ( Fig 12 D), long, sometimes branched, cavernous cylinders, 1–2 cm in diameter (sometimes up to 5 cm) and up to 20–40 cm long; ends can be lobed or tube-like; lobes are generally wider than their supporting cylinders or bases; lobes are usually rather cavernous and fluffy, with pinacoderm stretched over widely spaced supporting elevations. External colour is bright scarlet to orange; internal colour is orange to orange yellow; when dry the external colour becomes tan. Pinacoderm supported by tracts of spicules protruding from main fibres; elevated and stretched over fibre ends on lobes.

Oscules are circular, small, 1–4 mm in width, regularly scattered throughout the body and sometimes on the lobes; there are also holes visible under the pinacoderm with the same diameter of the oscules giving it a honeycomb-like aspect; separation between holes 2–8 mm. Exposed surface usually fouled excepting around body oscules and on lobes and top of tubes. The tube openings are 3–10 mm in diameter. Its fresh consistency is spongy, softer in the lobes; it becomes harder in the dry state. Choanosome is highly cavernous, its circular channels lined by a bright membrane; external walls 3–5 mm thick, internal walls 2–4 mm thick, channels 3–25 mm in width.

Primary fibres 50–110 Μm in diameter, heavily cored (5–9 spicules per cross section), echinated with whorls of 2–4 spicules. Secondary fibres never cored and slightly echinated, similar in diameter to primaries (40–90 Μm); tertiary fibres present and narrow (30–40 Μm in diameter), not cored and much less echinated than secondary fibres. Acanthostyles are straight to moderately curved, frequent acanthoxeas with whorls of 4 (3–6) spines although almost always some whorls could have only 1; length 43–210 (110±30.7) µm, width 2–13 (6±2.1) µm and 4–22 (9±2.3) whorls per spicule. Detailed lengths, widths and average number of whorls are shown in Table 2.

Remarks. This species typically grows on shallow to medium depth areas; in high-energy environments it could be seen filling spaces between rocks, crevices or holes. In the Bahamas it grows on reef slopes as tube-lobate forms, and fills crevices, or is buried in rubble/sandy bottoms in shallow and deep zones. In San Andres Island and Belize it grows on reef slopes and shallow crests as lobes protruding from bodies filling crevices. In Rosario Islands it grows as long tubes between stands of Halimeda spp., or as crevice-filling lobes, and as lobed cylinders in between and below massive, foliose and platy corals. In Santa Marta it grows as lobes filling crevices in shallow rocks, or as tiny tubes with terminal oscules buried on rubble or sandy deeper bottoms.

Thanks to K. Rützler and C. Piantoni, we could examine a spicule mount and some old and recent photographs of the holotype of A. schmidti . Lehnert & van Soest (1999) said that this species is similar to Zea (1987) and van Soest & Stentoft's (1988) descriptions of A. sceptrum . After a review of all the material involved (Zea’s and van Soest’s) we disagree because this assumption overlooks the dense choanosome of A. sceptrum with tiny channels and an axial condensation of the skeleton, features not evident in A. schmidti . Also, compared to A. sceptrum , spicules of A. schmidti have incomplete whorls of thorns and shorter lengths. A. schmidti spicules show up to four spines per whorl, while in sceptrum they are usually six or more (noted by Dr. P.M. Alcolado pers. comm.). Instead, this species and A. sventres Lehnert & van Soest 1996 (see below) have rather similar characters, especially skeleton and spicule architecture. Indeed, Alcolado (2002) considers them synonyms.

We did not collect enough microscopical nor DNA evidence ( Parra-Velandia 2011) to support A. schmidti as a separate species from A. sventres , there being often intermediate morphotypes. For the time being, we decided to keep them as separate species, pending further work. Thus, in our material we decided to attribute the name A. schmidti to the repent, thin (up to 2 cm in diameter), long branched, hollow forms with tube-like ends with an apical oscule or with fluffy lobed ends; also to softer crevice-filling and lobed forms. Thicker, more robust, crevice filling, with larger and firmer lobes, or football shaped, large roundish specimens (formerly considered a redorange morphotype of A. dispar ) are here attributed to A. sventres . The reason behind this decision was that A. schmidti forms have subtle but consistent morphological differences from what Lehnert & van Soest (1996) called A. sventres (gross tubular-finger to ball-shaped forms, with less scattered oscules and many of those as keyholes). But perhaps A. sventres is but one of the many forms that A. schmidti takes. More informative DNA sequences and/ or a closer examination of material where the two forms coexist would be needed to take a final decision. See further discussion under A. sventres below.

We have doubts regarding the identity of Wintermann-Kilian & Kilian (1984) material of A. schmidti from Santa Marta ( Colombia); as they did not report colour, it could belong to this species, or to A. sventres , or to A. wiedenmayeri . The same could be said for the compilation of Brazilian records for A. schmidti by Muricy et al. (2011), as at least Muricy et al. (2008) record probably belongs to A. wiedenmayeri on account of its brown color.

Figures

FIGURE 1. SEM images of Agelas. A) Spicules of A. conifera holotype. B) Spicules of A. clathrodes holotype. C) to D) Fibre skeleton with primary and secondary fibre echination, in A. citrina (C), A. dispar (D, curved fibres) and A. conifera (E). F) Detail of the skeleton of A. conifera showing coring spicules in a broken primary fibre. G) Detail of the skeleton of A. citrina with its long spicules.

FIGURE 9. Photographs of Agelas repens from Jamaica. A) Dry Holotype at ZMA. B) in situ, hanging from the wall of a reef slope crevice. C) Several freshly collected specimens; the scale represents 20 cm length and 0, 5 cm width.

FIGURE 12. Photographs of Agelas schmidti. A) Small round, tapered finger from Belize. B) Minute open tubes from Rosario Islands, Colombia. C) Fouled finger, the Bahamas (center only). D and E) Holotype at USNM (courtesy of K. Ruetzler and C. Dietrich).