Eurypon hookeri, Recinos & Pinheiro & Willenz & Hajdu, 2020

Recinos, Radharanne, Pinheiro, Ulisses, Willenz, Philippe & Hajdu, Eduardo, 2020, Three new Raspailiidae Hentschel, 1923 (Axinellida, Demospongiae) from Peru, Zootaxa 4778 (3), pp. 521-545 : 534-537

Eurypon hookeri sp. nov.

( Figure 3 , Table 1–2)

Type locality: Peru, Bahía Independencia, Islas Lobos de Afuera, Lambayeque Region.

Holotype. MNRJ 11363 , West of Bahía Independencia (06°56’57.07” S– 80°43’30.70” W), Islas Lobos de Afuera, Peru, 11 m depth, coll. Y. Hooker & K. Aguirre (06/X/2007) . Paratype. MNRJ 11408 , Callejon Los Lagartos (06.93689° S– 80.70509° W), Islas Lobos de Afuera, Peru, 22 m depth, coll. Ph. Willenz & Y. Hooker (09/ X/2007) .

Diagnosis. Crustose sponge, with deep ruby red colour, ectosomal styles (232–427 / 1.7–6 µm), subectosomal (subtylo)styles (859–1604 / 13–20 µm), and echinating acanthostyles (I = 158–463 / 12–24 µm; II = 107–169 / 7–11 µm).

Description ( Figs 3A–B ). Crustose sponge up to a few millimetres thick only, reaching over 15 cm in largest diameter, with rather irregular outline resulting from the tridimensional underlying substrate. MNRJ 11363 (holotype) was so thin, that the underlying substrate was visible by transparency, despite the sponge’s intense ruby red colour. Consistency soft. Surface optically rugose, bearing numerous, scattered, round oscules, sometimes with short chimneys 0.5–2 mm diam. Colour deep ruby red in life, brown after preservation. MNRJ 11408 (paratype) presents the same colour as the holotype.

Skeleton ( Fig. 3C ). Ectosome pierced by acanthostyles and (subtylo)styles, often surrounded by bouquets of smaller styles. Subectosomal and choanosomal skeletal structures microcionid, and overlapping, with short longitudinal fibre nodes cored and echinated by acanthostyles of varied dimensions and large (subtylo)styles. Fibre nodes may bifurcate, but appear not to anastomose.

Spicules ( Figs 3D–N , Table 2). Holotype: Ectosomal styles (232–332.6–427 / 1.7–3.8– 6 µm): smaller, smooth, slender, slightly curved, tapering gradually towards the apex, and occasionally also towards the base, rounded heads and hastate tips ( Figs 3 G–I). Subectosomal (subtylo)styles (859–1236.7–1604 / 13–16.9– 20 µm): large, smooth, straight or slightly curved, oval heads only a little swollen, sharp apex, mucronate tips ( Figs 3 D–F). Echinating acanthostyles I (158–304.2–463 / 12–16.3– 24 µm): large, straight or slightly curved, spined all over, but less so near the apex, spines conical or slightly bent as hooks, generally rounded heads and hastate tips ( Figs 3J, 3 M–N). Echinating acanthostyles II (107–129.2–169 / 7–9.3– 11 µm): smaller, slightly curved or bent close to the base, spined all over, but less so near the apex, spines conical or bent as hooks, with rounded tyle and acerate tips ( Figs 3 K–L).

Bathymetric distribution and ecology. Specimens collected at 11–22 m depth range, from a vertical rocky substrate. MNRJ 11408 was associated to a dictyoceratid sponge.

Distribution. Only known from the archipelago Islas Lobos de Afuera (Lambayeque), in Peru.

Etymology. The species name hookeri honours Yuri Hooker who led our fieldwork and was our indefatigable buddy diver.

Remarks. Eurypon hookeri sp. nov. is assigned to the genus by the presence of a raspailiid ectosomal architecture neighboring a basal microcionid arrangement with short longitudinal fibre nodes cored and echinated by acanthostyles of varied dimensions and large (subtylo)styles. The seven species of Eurypon known from the Central and Eastern Pacific ( Table 1) could be easily differentiated on the basis of spicule features. Three species have additional categories of subectosomal spicules, viz. two in E. brunum and E. nigrum , and three in E. miniaceum , which contrasts to the single category present in E. hookeri sp. nov. Eurypon hookeri sp. nov. differs from E. debrumi by the latter’s lack of acanthostyles and ectosomal styles, and from E. diversicolor by the latter’s lack of ectosomal styles. Eurypon hookeri sp. nov. has two categories of acanthostyles, thus differing from E. tylospinosum with only one. The most similar species appears to be E. patriciae from Mexico, but the latter has slightly larger and stouter subectosomal megascleres (up to 2400 / 25 µm vs 1604 / 20 µm in Eurypon hookeri sp. nov.), and smaller and thinner acanthostyles I and II (up to 180 / 7.5 µm and 87.5 / 5 µm, respectively vs 463 / 24 µm and 169 / 11 µm in Eurypon hookeri sp. nov.). Besides, E. patriciae is yellow or green coloured, in marked contrast to the deep ruby colour exhibited by E. hookeri sp. nov. E. lacertus sp. nov., described above, is markedly distinct starting from its orange colour when alive, slightly larger ectosomal and subectosomal megascleres (607 µm and 2100 µm, respectively vs 427 µm and 1604 µm in E. hookeri sp. nov.), and possession of a single category of acanthostyles. Eurypon hookeri sp. nov. is compared below to other Eurypon spp. from various parts of the world ( Table 1, including taxonomic authorities).

The number of categories of acanthostyles (two) distinguishes the new species from 30 additional species reported to possess only a single category of echinating acanthostyles. The latter group comprises E. cactoides , E. calypsoi , E. cinctum , E. clavatella , E. clavatum , E. coronula , E. distyli , E. encrusta , E. fulvum , E. graphidiophora , E. hispidulum , E. hispidum , E. incipiens , E. inuisitatiacanthostyla , E. lacazei , E. longispiculum , E. major , E. mixtum , E. mucronale , E. obtusum , E. polyplumosum , E. pulitzeri , E. radiatum (sensu Burton 1930), E. scabiosum , E. sessile , E. simplex , E. spinularia , E. toureti , E. vescicularis , and E. viride . Among these, five species were reported with exceedingly varied acanthostyle dimensions, which might hide two separate categories upon closer examination: E. cinctum (31–316 µm), E. hispidum (70–352 µm), E. polyplumosum (60–350 µm), E. radiatum (100–400 µm, sensu van Soest et al. 2000), and E. viride (113–365 µm). The first of these has larger ectosomal megascleres (styles or oxeas). Eurypon hispidum has subectosomal subtylostyles as small as 300 µm, in contrast to similar smallest spicules being over 800 µm long in E. hookeri sp. nov. Eurypon polyplumosum has much smaller subectosomal tylostyles (300–375 µm long), in marked contrast to similar spicules being mostly over 1000 µm long in the new species. In E. radiatum , notwithstanding the incompleteness of its description, Burton (1930) reported subectosomal megascleres only as thick as 12 µm, thus much more slender than the 20 µm thick megascleres observed in the Peruvian sponge. Eurypon viride has subectosomal megascleres that can be smaller (570 µm vs 859 µm in Eurypon hookeri sp. nov.), thinner acanthostyles (up to 14 µm vs up to 24 µm in Eurypon hookeri sp. nov.), and lastly, possesses trichodragmas, which are absent in E. hookeri sp. nov.

Seven species possess subectosomal acanthostyles, thus diverging from what was observed in the new species. Five of these, namely E. hispidulum , E. incipiens , E. mixtum , E. mucronale , and E. scabiosum , possess only a single category of echinating acanthostyles, as discussed above, and are thus considered sufficiently distinct as to avoid any possible confusion with the new species. The remaining two, viz. E. lamellatum and E. miniaceum can be distinguished by the following specific traits. Eurypon lamellatum has very large, albeit rare, choanosomal megascleres of 2900 µm in length, as well as much larger echinating acanthostyles (725–950 µm long). These spicules contrast to similar ones only as large as 1600 µm and 463 µm long, respectively, in Eurypon hookeri sp. nov. Similarly, E. miniaceum has much larger and stouter subectosomal megascleres, and much smaller echinating acanthostyles. The former can reach 3000 x 30 µm, and the latter, only 120 µm, both being quite different from similar spicules occurring in Eurypon hookeri sp. nov., as discussed above.

Four species lack acanthostyles ( E. hookeri sp. nov. has two categories): E. lictor , E. spitzbergens e, E. topsenti , and E. unispiculum . Eurypon lictor and E. spitzbergense further differ from E. hookeri sp. nov. by their much larger subectosomal megascleres (2500 µm long vs 1604 in E. hookeri sp. nov.). The former still possesses much larger ectosomal spicules (575–1000 µm long vs 232–427 µm long in E. hookeri sp. nov.), and shares with E. topsenti the presence of trichodragmas. These traits set both species apart from E. hookeri sp. nov. Eurypon unispiculum , if indeed an Eurypon , is unique in having a single category of spicules, likely subectosomal styles only half as long as the largest ones seen in E. hookeri sp. nov., who has in addition ectosomal megascleres and two categories of echinating acanthostyles, all un-corresponded in Carter’s (1880) species.

Another two species have no ectosomal styles, while E. hookeri sp. nov. has them. Species where this spicule category is absent include E. clavigerum and E. duoacanthostyla . Eurypon clavigerum has thinner subectosomal megascleres (12.5 vs 13–20 µm in E. hookeri sp. nov.) and acanthostyles (12 vs 12 – 24 µm in E. hookeri sp. nov.). The latter with spines seemingly restricted to their heads, while distributed all along the shaft in the new species. Eurypon duoacanthostyla has much smaller and slender subectosomal styles (250–320 / 5–8 vs subtyles. 859–1604 / 13–20 µm long in E. hookeri sp. nov.) and acanthostyles (138–280 / 6–9 vs 107–463 / 7–24 µm in E. hookeri sp. nov., categories I and II compiled).

Eight species remain to be contrasted to E. hookeri sp. nov., namely E. clavilectuarium , E. denisae , E. gracile , E. oxychaetum , E. potiguaris , E. suassunai , E. urizae , and E. verticillatum . Four of these are easily distinguished by their much larger subectosomal megascleres (largest spicules 2125–3150 µm long), viz. E. denisae , E. oxychaetum , E. potiguaris , and E. urizae in contrast to up to 1604 µm in E. hookeri sp. nov. Of the remaining four, three have much more slender echinating acanthostyles (up to 6–13 µm thick, as opposed to up to 24 µm in E. hookeri sp. nov.). These are E. gracile , E. suassunai , and E. verticillatum . The first, and the last of these have subectosomal megascleres which are much slenderer than those in E. hookeri sp. nov. (up to 8–10 µm thick, in contrast to up to 20 µm in E. hookeri sp. nov.). Eurypon suassunai further differs by the smaller dimensions attained by its smallest acanthostyles (down to 54 µm vs 107 µm in E. hookeri sp. nov.).

The above remarks clearly set E. hookeri sp. nov. apart from all 52 previously known species of Eurypon , as well as from E. lacertus sp. nov. described above.

Figures

FIGURE 3. Eurypon hookeri sp. nov. A–B specimens alive (holotype, MNRJ 11363; and paratype, MNRJ 11408; respectively); C, skeletal architecture in transverse ground section showing the ectosome and choanosome; D–F, large subectosomal (subtylo)style with details of head and tip; G–I, ectosomal style with details of head and tip; J–L, echinating acanthostyles of different sizes; M–N, detail of head and tip of acanthostyle I. Scale bars: A, 2 cm; B, 1 cm; C, 200 µm; D, J–L, 100 µm; E–F, M–N, 20 µm; G, 50 µm; H–I, 10 µm.