Agelas sceptrum ( Lamarck, 1815 )

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 : 315-316

Agelas sceptrum ( Lamarck, 1815)

Figs. 5 , 7 C, 15B

Etymology from Latin, meaning a ceremonial or emblematic stick ( Sceptre ). Alcyonium sceptrum Lamarck, 1815: 163 , Pl. II, Fig. 5 .

Synonyms and taxonomic treatment in Zea (1987). In addition:

Agelas sceptrum ; Álvarez & Díaz 1985: 87, Fig. 25; van Soest & Stentoft 1988: 100: Fig. 49; Kobluk & van Soest 1989: 1210; Lehnert 1993: 50, Figs. 23, 87–88; Gammill 1997: 31, Figs. 19, 32; Lehnert & Van Soest 1998: 81; Lehnert & Van Soest 1999: 155; Assmann 2000: 38, pl. 4, Fig. A.; Valderrama 2001: 50; Mothes et al. 2007: 84; Zea et al. 2009; Muricy et al. 2011: 39; Alcolado & Busutil 2012: 69.

[Non: Agelas sceptre ; Alcolado 1976: 5; Agelas sceptrum ; Alcolado 2002: 61, = Agelas cervicornis ( Schmidt, 1870) ]

Agelas cylindricus ; Alcolado 1980: 3; 2002:61.

[Non: Agelas cylindricus ( Carter, 1883: 314) , = Agelas cervicornis ( Schmidt, 1870)

Agelas sp. 5; Pulitzer-Finali 1986: 112, Fig. 32.

Material and distribution. Holotype not examined (but see remarks), deposited at the Muséum National d’Histoire Naturelle in Paris. The material reviewed here includes (but is not restricted to) specimens from the Bahamas (INV– POR 938), Jamaica (INV– POR 1001, 1005), Belize (INV– POR 954), San Andres Island (INV– POR 980, 981, see also Zea 1987 who recorded it from Old Providence), Rosario Islands (INV– POR 967, see also Zea 1987), Curacao (INV– POR 909) and Barbados (INV– POR 913).

Other records (including accounts by Zea 1987): Florida Keys, Bahamas ( Gammill, 1997; Assmann 2000; Zea et al. 2009), Cuba ( Alcolado 1980; 2002), Jamaica (van Soest & Stentoft 1988), Guadeloupe ( Alcolado & Busutil 2012), Barbados (van Soest & Stentoft 1988), Curaçao, Bonaire (Kobluk & van Soest 1989), Los Roques ( Venezuela, Álvarez & Díaz 1985), Urabá in Colombia ( Valderrama 2001), and NE Brazil ( Mothes et al. 2007; Muricy et al. 2011). Despite the fact that it does not occur at Santa Marta, Colombia, perhaps because of local upwelling, we consider A. sceptrum as a tropical northwestern Atlantic species. Our specimens were found from 7 to 35 m in depth, abundant at 21–25 m; van Soest & Stentoft (1988) report a specimen from 100 m depth.

Description. This sponge usually forms cylindrical branches ( Fig. 5 A, 5B), erect or repent ( Fig 5 D), solitary or ramified ( Fig 5 E); it can also develop oscular lobes or thickly encrusting coats; variable length, 10–30 cm, 1–3 cm in diameter ( Fig 5 C, 5F). External colour orange to orange yellow; internal colour orange yellow; the colour becomes darker after collection. Its consistency is compressible, flexible and elastic in life or preserved, difficult to tear or cut, but still flexible in dry state. Pinacoderm sustained by tracts of spicules, collapses out of the water revealing subdermal channels (2–4 mm wide).

Scattered oscules at the same level of the pinacoderm, 3–6 mm in diameter, with a membranous ring ( Fig 5 A); sometimes the oscules are aligned in the upper part of branches, but this is not a typical feature; small ostia <1 mm are dispersed over the surface. The interior is dense but porous, with tiny channels (<2 mm).

The skeletal architecture corresponds to an axial skeleton of loose axial fibres, from which primary fibres radiate to the pinacoderm. Primary fibres, 60–100 µm in diameter, cored (1–6 spicules per cross section) and echinated; secondary fibres not cored, sparsely echinated, 50–80 µm in diameter; tertiary fibres not present. Acanthostyles are slightly to moderately curved; 6–8 spines per verticil; length 78–249 (137±34.5) µm, width 5–18 (9±2.2) µm and 726 (13±3.6) whorls per spicule. Detailed lengths, widths and average number of whorls are shown in Table 2.

Remarks. Thanks to Dr. Domart-Coulon we examined several digital photographs of the holotype spicule and skeleton mounts. After several discussions with Dr. P.M. Alcolado, we agreed that his records of Agelas cylindricus from Cuba are A. sceptrum . This species grows both exposed and cryptic on reef slopes and cryptic under rocks and corals on shallow areas. There is a rather consistent variation in predominant shape and microhabitat location with the geographical location. In Jamaica, Curacao, Barbados and Cuba (Dr. P.M. Alcolado pers. comm.), it is more often exposed, characteristically forming long, divided branches whose bases are erect but the apices tend to curve, falling down to the substratum. In the southern Caribbean ( Belize, San Andrés Island, continental coast of Colombia), the species forms thinner repent branches that creep under corals, rarely becoming erect, or only at their tips. These creepy, cryptic specimens somewhat resemble Agelas repens Lehnert & van Soest 1998 (see discussion below). In the Bahamas, although the species is frequently found living under overhangs and in vertical reef walls, it tends to be erect and thick. Dr. P.M. Alcolado reports (pers. comm.) that this species is often infested with wine red individual zoanthids that stain the hands.

Young or small specimens of A. conifera could be easily confused with A. sceptrum , but the protruded cones and short spicules in the former versus the levelled oscules and longer spicules in the latter allows to separate them. Agelas sp. 5 ( Jamaica) as described by Pulitzer-Finali (1986) belongs to this species. Its spicule size coincides with that of our own material from Jamaica (see Table 2).

Figures

FIGURE 5. Photographs of Agelas sceptrum. Note the oscules position with respect to the growing axis. A) The Bahamas. B) Barbados; dark spots correspond to zoanthids. C) Erect specimen from Belize. D) Erect and exposed specimen from Curaçao. E) Branched erect specimen, Jamaica; note the branch tip attachment. F) Minute erect specimen from San Andres Island, Colombia.

FIGURE 7. Photographs of Agelas conifera. Note the position of oscules with respect to the growing axis. A) Holotype; note the cones. B) The Bahamas. C) Yellow right specimen of this species, compared to a A. sceptrum, left specimen, Barbados. D) Pink specimen from Belize. E) Curaçao. F) Dark specimen from Los Roques, Venezuela; note the membranous oscules.