Hymedesmia ( Hymedesmia ) peruana, Salani & Willenz & Fernandez & Hajdu, 2022

Salani, Sula, Willenz, Philippe, Fernandez, Julio C. C. & Hajdu, Eduardo, 2022, Three new Hymedesmia Bowerbank, 1864 (Demospongiae, Poecilosclerida Hymedesmiidae) from the Southeast Pacific (Peru and Chile), Zootaxa 5165 (2), pp. 217-240 : 221-223

Hymedesmia ( Hymedesmia) peruana sp. nov.

( Figures 3–4 ; Table 1 )

Material examined. Holotype ― MNRJ 13694 (Vouchers: RBINS – IG 32841 –POR 13694, MHNG 85931 ), Isla Foca , Piura Region ( 5.19529S, 81.2160W), depth 26 m, coll. Y. Hooker & M. Rios ( 13/XII/2009).

Diagnosis. Hymedesmia ( H.) orange in situ. Acanthostyles I echinating and acanthostyles II forming microconules at surface. Three categories of acanthostyles, bigger and intermediate ones partially spined, and smaller entirely spined (I. 262–360 × 7–10 µm; II. 118–231 × 3.5–10 µm; III. 65–106 x 2.6–6.1), tornotes (117–146 ×1.6–3µm), arcuate chelae (14.7–21.3 µm).

Description ( Fig. 3A ). Thinly encrusting sponge ( 8.8 cm 2), less than 1 mm thick ( 0.16 to 0.6 mm). Consistency very soft and fragile. Surface smooth. Color in life orange ( Fig. 3A ), turning to beige when preserved in ethanol.

Skeleton ( Figs 3B–C ). Ectosomal skeleton with ectosomal strongyles forming bundles (4 to 7 spicules) extending up from the substrate. Choanosomal acanthostyles I may pierce the surface occasionally ( Fig. 3B ). Subectosomal and choanosomal skeletons overlapping, with subectosomal canals (45–265 µm diameter). Choanosomal skeleton composed of typical hymedesmioid structure, consisting of a basal layer of spongin with acanthostyles I and II erect on the substrate ( Fig. 3B–C ). Acanthostyles I pierce the ectosome and the acanthostyles II support the surface, forming microconules. Isochelae appear scattered in the ectosome, and some tylostyles lay parallel to, or flat on the substratum.

Spicules ( Figs 3D–K , 4 ; Table 1 ). Ectosomal diactines: tornotes, straight, isodiametric ( Fig. 3G ), with conical extremities, 117– 132.3 –146 (± 11.8) × 1.6– 2.2 –2.9 (± 0.4) µm ( Figs 3H–I ). Choanosomal acanthostyles I ( Figs 3D , 4 ): hastate to acerate tip tapering gradually, rounded base; shaft straight, with spines occupying the basal two thirds of its length; spines mostly slightly curved, those of the base larger than those of the shaft, 262– 300.7 –360 (± 34.3) × 7.7– 8.3 –9.8 (± 0.8) µm. Choanosomal acanthostyles II ( Figs 3E , 4 ): similar to acanthostyles I, but slightly smaller, 118– 182.7 –231 (± 40.3) × 3.5– 6.5 –9.6 (± 2.0). Choanosomal acanthostyles III ( Figs 3F , 4 ): straight, tapering gradually, acerate tip and rounded base, spined all over, 65.7– 78.2 –106 (± 11.1) × 2.6– 4.1 –6.1 (± 0.8) µm. Arcuate isochelae ( Figs 3J–K ): one free spatulate ala and two lateral alae semi-fused with the shaft ( Fig. 3K ), shaft characteristically curved, bow shaped, 14.7– 16.4 –21.3 (± 1.4) µm.

Ecology. This single specimen was epibiontic on a bivalve shell at 26 m depth.

Distribution. Known only from its type locality, Isla Foca.

Etymology. The species name “ peruana ” is used as a noun in apposition that refers to Peru.

Remarks. Hymedesmia ( H.) peruana sp. nov. differs from H. ( H.) santarositae sp. nov., by the combined absence of sigmas and microstrongyles ( Table 1 ). Hymedesmia ( H.) croftsae Goodwin et al., 2012 has similarly small ectosomal tornotes, but these are strongylote, and acanthostyles, albeit exhibiting similar overall dimensions, seemingly cannot be separated in three categories. Hymedesmia ( H.) humboldti sp. nov. also bears some similarities, which are further elaborated in its remarks (see below). Other species of Hymedesmia ( H.) considered here (reported from the Antarctic, Sub-antarctic, SW Atlantic and SE Pacific) possess considerably larger spicules, none has three categories of acanthostyles, and many are only known from the deep sea.

Figures

FIGURE 3. Hymedesmia (H.) peruana sp. nov. A, live specimen (MNRJ 13694); B–C, skeleton architecture in transverse ground section; D, choanosomal acanthostyle I; E, choanosomal acanthostyle II; F, choanosomal acanthostyle III; G, ectosomal tornote; H–I, details of G; J–K, isochelae. Scale bars: A, 2 cm; B–C, 200 µm; D–G, 100 µm; H–I, 20 µm; J–K, 10 µm.

FIGURE 4. Hymedesmia (H.) peruana sp. nov. Bar plot illustrating the size frequency distribution obtained by the Sturges Algorithm for the acanthostyles (n = 100).