Parahigginsia strongylifera, Van Soest & Meesters & Becking, 2014

Van Soest, Rob W. M., Meesters, Erik H. W. G. & Becking, Leontine E., 2014, Deep-water sponges (Porifera) from Bonaire and Klein Curaçao, Southern Caribbean, Zootaxa 3878 (5), pp. 401-443 : 423-425

Parahigginsia strongylifera new species

Figures 14a–d , 15a–f

Material examined. Holotype: RMNH Por. 9251, Caribbean Netherlands, Bonaire (Dive 4), 112.08°N 68.2938°W, depth 238 m, on a limestone rockwall, coll. L.E. Becking & E. Meesters, field nr. BON4/ BDR048 , 1 June 2013.

Description. Pale blue, encrusting sponges ( Fig. 14a ) forming small lobes with raised oscules ( Fig. 14b ), individual lobes approximately 2 x 1 x 1 cm in size. The preserved holotype material consists of fragments of approximately 1–2 cm in size ( Fig. 14c ). Individual lobes may coalesce with nearby lobes, and may be connected by thin tissue strands on the substratum. Consistency soft, easily damaged.

Skeleton. The ectosomal skeleton consists of a thin layer of spined microxeas ( Fig. 15e ) covering a confused choanosomal reticulation ( Fig. 15d ), constructed from individual strongyles or vaguely aligned bundles of two or three. No clearly developed meshes or tracts. Microxeas are also profusely present in the choanosome.

Spicules ( Figs. 14d ). Strongyles, acanthomicroxeas.

Strongyles ( Fig. 15a ), curved, often with slightly asymmetrical ends, 290– 341 –370 x 10– 15 – 18 µm

Acanthomicroxeas ( Figs. 15b–c 1 ), curved gently, not abruptly, with thin somewhat irregularly distributed spines (denser at the apices and in the center), 75– 93 –120 x 1– 1.8 – 2.5 µm.

Ecology and distribution. Deep water (238 m) off the coast of SW Bonaire, on volcanic outcrops.

Etymology. The name refers to the strongyle megascleres.

Remarks. The genus Parahigginsia is so far monotypical, erected for the New Zealand deep water species P. phakelloides Dendy, 1924 , subsequently reported also from New Caledonia by Lévi & Lévi (1983). The assignment of our specimen to this genus is based on the combination of a dense isotropic skeleton of smooth diactines arranged in vague bundles and an ectosomal cover of thin curved acanthoxeas. P. phakelloides has a similar skeleton, but the megascleres are more definitely curved oxeas, whereas P. strongylifera n. sp. predominantly has (aniso-)strongyles. The megascleres and microscleres of both species are in the same size range. P. phakelloides has a lamellate growth form, up to 14 cm high, 8 cm wide and 2.5 mm thick, quite different from the encrusting-lobate P. strongylifera n. sp. Both species occur at comparable depths ( P. phakelloides was collected from 126 m).

Hooper (2002) assigned the genus Parahigginsia to the family Desmoxyidae , for priority reasons renamed as Heteroxyidae in Van Soest & Hooper (2005). This family is likely polyphyletic ( Morrow et al. 2012). Parahigginsia was reassigned to a family Stelligeridae , along with several other heteroxyid genera. Since only limited evidence of mostly molecular nature was presented to justify the proposed reassignment, we prefer to retain Parahigginsia in the family Heteroxyidae until a comprehensive integrative classification of these genera and families has been published.

Figures

FIGURE 1. Map showing the positions of Bonaire and Klein Curaçao (Southern Caribbean), where the present collections were obtained. Insets show details of locations and course of dives 2–4 of the Curasub.

FIGURE 14. Parahigginsia strongylifera n. sp., habit in situ, b. detail of habit in situ, c. preserved holotype RMNH Por. 9251, d. spicules of holotype.

FIGURE 15. Parahigginsia strongylifera n. sp., holotype RMNH Por. 9251, a–c. SEM images of the spicules, a. strongyle, b. acanthomicroxea, c. details of apex and middle part of acanthomicroxea, d–e. light microscopy images of skeleton, d. cross section of skeleton, e. detailed view of peripheral skeleton showing ectosomal cover of acanthomicroxeas.