Agelas Duchassaing & Michelotti, 1864

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 : 304-306

Genus Agelas Duchassaing & Michelotti, 1864

Type species Agelas dispar Duchassaing & Michelotti, 1864

Remarks. The etymology and reasoning behind the word Agelas can only be guessed, as the original authors ( Duchassaing & Michelotti 1864) gave no explanation. In his work about Bahamian sponges, Wiedenmayer (1977) discussed the feminine gender of Agelas and established that it does not exist as a Greek noun but only as a root; unfortunately, he did not give a meaning for that root. A recent work of Greek names in Porifera science ( Voultsiadou & Gkelis 2005) established that άγελάς means “belonging to a herd”. A Spanish-Greek dictionary ( Pabón 1967) gives additional meanings for the word, although with a different spelling that means, at least in Spanish, a masculine gender: άγελη ς: crowd, band, section or group. Greek mythology names several Agelao, the most relevant being the shepherd/slave commanded by Priamo, King of Troy, to kill his son Paris due to the dreamprophecy of his wife Hecuba. In his mother’s dream, Paris puts Troy on fire. Finally, the history remembers at least two Corinth kings under that name ( Heffner 1924; Dunbabin 1948).

The species belonging to this genus have several main forms: branching ( Fig. 3 E, 9E), tubular ( Fig. 8 E), globular or ball-shaped ( Figs. 2 B, 14D), lobate ( Fig. 8 B, 8C, 11E), fan-shaped ( Figs. 11 D, 13H), columnar, clavate or thickly encrusting ( Fig. 11 C). Agelas of larger sizes were observed in Rosario Islands ( Colombia), i.e., 2–3 m in diameter fan-shaped Agelas clathrodes ( Fig. 11 E). Smaller sizes were observed at the mouth of Rio Bueno ( Jamaica), e.g. thin-branched A. repens of 50 cm long but only 0.25 cm in diameter ( Fig. 9 ).

The choanosome is typically cavernous although sometimes this feature is not apparent as channels can be narrow (<2 mm) resulting in a dense aspect, as in A. sceptrum , A. conifera or A. cervicornis . The ectosome is a pinacoderm supported by tracts of spicules protruding from the perpendicular main fibres; when dry the pinacoderm retracts on its supporting skeleton, and the ectosome takes on a pockmarked aspect, remarkable in A. conifera and not so evident in A. clathrodes . The channels and some apertures can have a lining pinacoderm rather smooth and brilliant.

This genus possesses characteristic acanthostyle spicules with regularly spaced verticils of thorns ( Figure 1 A–B). It is not unusual to find acanthoxeas and, as far as we have searched, these appear unrestricted to any particular geographical area, but are found more in oceanic islands than in continental areas (Parra-Velandia pers. obs.).

A network of ascending primaries, interconnected by secondary and tertiary fibres ( Fig. 1 C–D), composes the spongin skeleton. The skeletal architecture ( Fig. 15 ) in all species reviewed here correspond to an axinellid skeleton, or variations of it, with the fibers forming a plumoreticulate mesh, as in A. conifera and A. sceptrum ( Fig. 15 A–B). Typically, the primaries ascend while radiating from the main axis of growth toward the pinacoderm; in some species ( A. conifera Fig. 11 A–D, Fig 15 A; A. dispar Fig. 2 A–H, Fig 15 E) this arrangement is evident enough to be perceived through the naked eye, while in others this is evident only in dried specimens ( A. clathrodes Fig. 5 A–F, Fig 15 D; A. dilatata Fig. 6A–H). Primary fibres are echinated and cored ( Figure 1 D–E); secondary fibers usually echinated and normally not cored (see A. cervicornis description); tertiary fibers are echinated but never cored.

At the species level and following morphological characteristics, it is possible to sort species groups out (see Table 1 ), with features such as skeleton, colour, spicules and ectosomal architecture, determining three main species groups. Below the group level, the main differences between species involve, in a minor degree, spicule architecture (length, verticil completeness, number of spines per verticil), and in a greater degree, external morphology. Each species group was named after a representative species and their characters are defined as follows:

rare, a=absent, p=present. Spicule architecture: length (mean, µm), width (mean, µm), verticils (mean number per spicule), s-spine number, c-verticil completeness

=complete, i=incomplete), a-axis curvature (sc=slightly curved, mc=medium curved, tr=straight). Sk-Skeletal arrangement: o=ortho, i=iso, a=aniso. Form: frame

=massive, r=ramose, t=tube, b=barrel), predominant shape, thickness. Choan-Choanosome: c=cavernous, s=solid. Eco-Ecology: b-biogeography (g=Greater Caribbean,

Caribbean, r=restricted distribution); h-habitat (x=exposed, c=cryptic, m=mixed, body filling crevices with exposed part); d-depth in the reef (s=shallow 0–5 m, m=medium 5–

m, d=deep 10–20 m, v=very deep> 20 m).

– dispar -like species group: more or less straight cored primary fibres, with secondary, rarely tertiary fibres; color dark brown alive and in spirit; short spicules with few but complete verticils, each one with few spines; and a dense pinacoderm. This species group includes A. dispar , A. wiedenmayeri and A. cervicornis .

– conifera -like species group: straight cored primary fibres; secondary fibres present, but never tertiary fibres; color yellowish light orange alive and light brown in spirit; long spicules with lots of spines in many verticils, and a loose pinacoderm. This species group includes A. conifera , A. tubulata , A. cerebrum , A. sceptrum , A. repens and A. dilatata .

– clathrodes -like species group: convoluted cored primary fibres; secondary and tertiary fibres present; color bright orange alive and orange in spirit; medium size spicules; few verticils, few spines per verticil and a dense pinacoderm sometimes ornamented by conules. This species group covers a species sub-group called schmidti - like, which exhibits a closer resemblance to the clathrodes -like species group; however the main differences are a reddish color in spirit, looser skeletal meshes and spicules with incomplete verticils. To the clathrodes - like species group belong A. clathrodes , A. citrina , A. schmidti and A. sventres ; the latter two belong to the schmidti -like species sub-group.

The species described below are arranged by species group and then sorted by date of original description.

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 2. Photographs of Agelas dispar. A) Holotype. B) Bahamas massive specimen; note clustered collared oscules, and small circular oscules. C) Barbados round lobate specimen. D) Belize. E) Jamaica. F) San Andres Island (Colombia) flabellate specimen; note the keyhole-shaped oscules. G) Rosario Islands (Colombia) lobate specimen.

FIGURE 3. Photographs of Agelas cervicornis. Note the aspect if openings. A) Cylindrical. B) Rough surface detail. C) Subcylindrical ramifications. D) Multiple ramifications from specimens of the Bahamas. E) wide flattened. F) Cylindrical. G) Rough surface detail. H) Subcylindrical specimen from Jamaica.

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 8. Photographs of Agelas tubulata. Note the position of oscules with respect to the growing axis plane. A) Holotype at ZMA. B) Jamaica. C) H. Lehnert image from ZMA photographic archives. D) Jamaica. E) Solitary tube, Belize; note the little tube bud at the lower left. F) Detail of the previous specimen. G) Robust tubes with irregular grooves at San Andrés Island, Colombia; note the even surface between grooves. H) Slender group of long tubes at San Andres Island; note predation marks.

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 11. Photographs of Agelas clathrodes. A) Holotype from Caracas, in the Zoologisk Museum København. B) Thick, fan-shaped specimen from the Bahamas. C) Encrusting specimen, Belize. D) Key-holes in a San Andres Island (Colombia) specimen. E) F. P-V. sitting on a large specimen at Rosario Islands (Colombia). F) Fouled specimen at Santa Marta, Colombia.

FIGURE 15. Scanned sections of dry specimens to show skeletal details; primaries as black fibers, secondaries as gray fibers. A) Agelas conifera; primaries subparallel. B) Agelas sceptrum; primaries subparallel. C) Agelas dispar. D) Agelas clathrodes. E) Agelas dispar. F) Agelas wiedenmayeri. Scale 5 mm for all photos.

Tables

TABLE 1. Main morphological features of Caribbean Agelas. Primary fibers: st = straight, un = undulated. Color in spirit: b = brown, y = yellowish, o = orange. Tertiary fibers:

Agelas dispar	Primary fibers st	Color b	Tertiary fibers r	length 130	Spicule architecture width verticils s 10 11 5–8	c c	a sc	Sk o	frame m	Form predominant shape thickness ear-like thin	Choan. c	b g	Eco h d x d
cervicornis	st	b	r	100	9 10 4–5	c	tr	o	r	even openings thin	s	r	x v
wiedenmayeri	st	b	r	140	9 12 3–9	c	cu	o	t	tube verythin	s	g	x v
sceptrum	st	y	a	140	9>13 6–8	c	sc	i	r	even openings thick	s	g	x v
dilatata	st	y	a	110	6>13 4–7	c	tr	i	m	fan shape medium	s	r	c v
conifera	st	y	a	140	10 <13 5–9	c	tr	i	r	elevated openings medium	s	g	x v
tubulata	st	y	a	110	6>15 5–8	c	tr	i	t	tube medium	s	g	x d
repens	st	y	a	180	8 16 5–6	c	tr	i	r	even openings thin	s	r	c v
cerebrum	st	y	r	115	7 <13 5–7	c	tr	i	b	barrel thick	s	r	x d
clathrodes	un	o	p	110	8 10 3–8	c	tr	a	m	fan shape thick	c	g	x v
schmidti	un	o	p	100	6 <9 3–6	i	mc	a	t	tube-like thin	s	g	m d
citrina	un	o	p	180	12 13 3–8	c	tr	a	m	fan shape, barrels medium	c	c	x v
sventres	un	o	p	130	9>9 4–7	i	sc	a	t	tube-like thin	c	g	m d