Eurypon lacertus Recinos & Pinheiro & Willenz & Hajdu 2020, sp. nov.

Eurypon lacertus sp. nov.

(Figure 2, Table 1)

Type locality: Peru, Islote El Lagarto, Islas Lobos de Afuera archipelago, Lambayeque Region.

Holotype. MNRJ 11334, Islote El Lagarto (approx. 6.93360° S– 80.70551° W), Islas Lobos de Afuera, Peru, 11 m depth, coll. Ph. Willenz & Y. Hooker (04/X/2007).

Diagnosis. Encrusting sponge, with orange colour, ectosomal anisoxeas (339–607 / 4–9 µm), subectosomal tylostyles (1294–2100 / 13–25 µm) and echinating acanthostyles (54–112 / 6–13 µm).

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Description (Fig. 2A). Thinly encrusting sponge, size 5 cm in its largest diameter, no thicker than 1 mm. Consistency soft and easily torn. Surface smooth, with barely visible subectosomal canals, converging to the few small, scattered, oscula (<1 mm diam). Colour orange in life, beige after preservation.

Skeleton (Figs 2 B–C). Ectosomal skeleton with ectosomal anisoxeas forming plumose bouquets surrounding the subectosomal tylostyles, which markedly pierce the surface. Subectosomal and choanosomal skeletons overlapping, composed of typical hymedesmioid structure, consisting of a basal layer of spongin, with large tylostyles and small acanthostyles, both erect on the substrate. Some spicules appear scattered in the sponge, and many tylostyles lay parallel to, or flat on the substrate.

Spicules (Figs 2 D–J). Ectosomal anisoxeas (339–488.4–607 / 4–6.3– 9 µm): smooth, irregularly curved or bent, blunt and acerate tips (Figs 2 G–I). Subectosomal tylostyles (1294–1705.1–2100 / 13–19.1– 25 µm): large, smooth, straight to slightly curved, tapering gradually, mucronate tips and round heads (Figs 2 D–F). Echinating acanthostyles (54–77.6–112 / 6–9.3– 13 µm): slender, straight, spined all over, spines conical or bent as hooks, with rounded tyle and acerate tips (Fig. 2J).

Bathymetric distribution and ecology. The sponge was collected from a nearly vertical rocky substrate, near the coarse, biogenic sand bottom, at 11 m depth. Short red algae and thinly encrusting coralinaceous algae surrounded it.

Distribution. Known only from its type locality, Islote El Lagarto, located at Islas Lobos de Afuera archipelago (Lambayeque).

Etymology. The species name, lacertus (lizard in Latin), refers to the type locality of the species, Islote El Lagarto.

Remarks. Table 1 contrasts micrometric data, as well as the geometry of spicules, and distribution of every known species of Eurypon to both of the new species described here, in addition to including taxonomic authorities. There are only seven species of Eurypon reported from Eastern and Central Pacific, all from shallow waters: E. brunum, E. debrumi, E. diversicolor, E. miniaceum, E. nigrum, E. patriciae, and E. tylospinosum. Eurypon lacertus sp. nov. is distinguished from its congeners mainly by spicule features. The Central and Eastern Pacific Ocean species E. brunum, E. diversicolor, and E. patriciae have two categories of acanthostyles, and E. debrumi has none, in contrast to a single category in E. lacertus sp. nov. Two species have two categories of subectosomal tylostyles, E. miniaceum and E. nigrum, while E. lacertus sp. nov. has only one. The species closest to E. lacertus sp. nov., both in morphological, as well as biogeographic aspects, appears to be E. tylospinosum from Mexico, but its ectosomal and subectosomal megascleres are much smaller and thinner (up to 460 / 2.5 μm and 575 / 15 μm vs 607 / 9 μm and 2100 / 25 μm in E. lacertus sp. nov.).

Following, the comparison is extended to species from other biogeographically more remote areas (Table 1, including taxonomic authorities). Ten species are differentiated from E. lacertus sp. nov. by the presence of two categories of acanthostyles. These include E. clavilectuarium, E. denisae, E. duoacanthostyla, E. gracile, E. incipiens, E. oxychaetum, E. potiguaris, E. suassunai, E. urizae, and E. verticillatum. Six additional species have subectosomal acanthostyles or strongyles, instead of the smooth tylostyles seen in E. lacertus sp. nov. These are E. hispidulum, E. inuisitatiacanthostyla, E. lamellatum, E. mixtum, E. mucronale, and E. scabiosum. In addition, E. inuisitatiacanthostyla, E. lamellatum, and E. mixtum lack ectosomal spicules of any sort. In the other three species, ectosomal spicules are of different morphology, viz. subtylostyles in E. hispidulum and E. scabiosum, and tornotes in E. mucronale. Acanthostyles are absent in another four species, which contrasts to their occurrence in E. lacertus sp. nov. Species without acanthostyles are E. lictor, E. spitzbergense, E. topsenti, and E. unispiculum. Six species have raphides or trichodragmas as microscleres, which were not found in E. lacertus sp. nov. These comprise E. cactoides, E. distyli, E. encrusta, E. graphidiophora, E. polyplumosum, and E. viride. Four species have much smaller subectosomal spicules than those of E. lacertus sp. nov. (up to 2100 μm), namely E. clavatella, E. fulvum, E. sessile, and E. spinularia (up to 470, 1500, 635 and 529 μm, respectively). Conversely, four species have larger acanthostyles: E. cinctum, E. hispidum, E. major, and E. simplex (acanthostyles up to 316, 352, 220 and 219 μm, respectively) in contrast to up to 112 µm in E. lacertus sp. nov. Eurypon hispidum and E. simplex further lack ectosomal megascleres. Other two species Eurypon lacazei and E. toureti have smaller acanthostyles (up to 80 and 60 μm vs 112 μm in E. lacertus sp. nov.). Eurypon calypsoi has much thinner subectosomal tylostyles and ectosomal spicules (only up to 10 and 3 μm, respectively in contrast to up to 25 and 9 μm in E. lacertus sp. nov.). Eurypon pulitzeri has larger subectosomal megascleres and acanthostyles (up to 2500 and 165 μm, respectively vs 2100 and 112 in E. lacertus sp. nov.). Eurypon lacertus sp. nov. differs from E. clavigerum and E. vescicularis by its possession of ectosomal megascleres; and from E. obtusum, by the latter smaller and thinner ectosomal spicules (up to 430 / 3 μm vs 607 / 9 μm in E. lacertus sp. nov.). Eurypon lacertus sp. nov. differs from E. coronula by the presence of stouter ectosomal styles (up to 9 μm vs 6 μm in E. coronula), and from E. clavatum by the much thinner subectosomal tylostyles (only up to 13 μm vs 25 μm in E. lacertus sp. nov.). Eurypon radiatum is rather distinct by its smaller ectosomal megascleres and larger acanthostyles (up to 350 and 400 μm in contrast to up to 607 and 112 μm in E. lacertus sp. nov.). Finally, E. longispiculum has subectosomal megascleres with much more markedly pronounced heads according to Carter’s (1876) illustration, ectosomal styles instead of anisoxeas, and the single specimen ever found came from deeper than 600 m in the Boreal NE Atlantic, which compounds for a highly improbable hypothesis of cospecificity with E. lacertus sp. nov.