Halichondria (Halichondria) prostrata Thiele, 1905

Cóndor-Luján, Báslavi, Arteaga, Alvaro, Polo, Christian, Arroyo, Yessenia, Willenz, Philippe & Hajdu, Eduardo, 2023, Shallow Suberitida (Porifera, Demospongiae) from Peru, Zootaxa 5264 (4), pp. 451-489 : 459-461

Halichondria (Halichondria) prostrata Thiele, 1905

( Figure 3 , Table 3)

Synonyms: Halichondria prostrata Thiele (1905) : 458, Fig. 2 , 73; Burton (1930): 333; Burton (1940): 117. Halichondria panicea Sarà (1978) : 20, Fig. 7 , 9C ; Carvalho & Hajdu (2001): 117.

Type locality. Quiriquina , Tumbes, Concepción, Chile .

Material examined. Three specimens. MNRJ 12884 , Islote , Atenas Beach , Paracas, Ica (13°49′38.71″ S-76 °18′07.41″W), 1.2 m depth, coll. Y. Hooker, Ph. Willenz & N. Mostajo, 13.XII.2008 . UCSUR 07-000057 and UCSUR 07-000058 , Sensor Station , Asia Island , Cañete, Lima (12°46′57.05′′S 76°37′12.19′′W), 5–8 m depth, coll. D. Cuba, 6.III.2019 .

Description. Specimens either smoothly incrusting or irregular with abundant projections of various shapes (lobate, ridged or digitiform). Surface with a transparent dermal membrane revealing the choanosomal skeleton underneath ( Fig. 3A ). Largest specimen (UCSUR 07-000041) measuring 7.0 x 3.4 x 1.1 cm (length x width x height), with largest projection 0.4 cm high. Oscula (max. diam. = 2 mm) located on the top of the projections. Consistency compressible and surface smooth.

Colour. Opaque, a lighter (nearly white) or slightly darker shade of yellow in life and beige in ethanol ( Fig. 3A ).

Skeleton. Cavernous, with canals and subectosomal lacunae ( Fig. 3B ). Ectosomal skeleton, easily detachable, thin tangential and transparent layer, spicule arrangement as a criss-cross of spicules, some of which seem to form a loose palisade layer (in transversal view, Fig. 3C ). Choanosomal skeleton, multispicular ascendent tracts attached by spicules in some parts, abundant free spicules in confusion.

Spicules. Megascleres.Oxeas, slightly bent at centre,tapering gradually(200–380 x4–13 µm, Fig.3D–F , Table3).

Ecology. Specimens were found attached or close to other organisms. MNRJ 12844 encircled many anemones, while UCSUR 07-000057 was found on a polychaete tube.

Geographic and bathymetrical distributions. SE Pacific: Chile ( Thiele 1905) and Peru (Asia Island and Paracas, this study). SE Atlantic: Comodoro Rivadavia ( Burton 1940) and Tierra del Fuego ( Sarà 1978; Carvalho & Hajdu 2001). South Georgia ( Burton 1930). Antarctic ( Koltun 1964; Kunzmann 1996) but needs revision (see remarks). MEOW in Peru: Humboldtian ecoregion ( Spalding et al. 2007). From intertidal ( Sarà 1978) to 8 m depth (this study).

Remarks. The Peruvian specimens match Halichondria (H.) prostrata from Chile ( Thiele 1905). Although they have apparently slightly longer and stouter oxeas (195–380 x 4–13 µm) when compared to the holotype (300–320 x 9 µm), this can be considered intraspecific variation. Halichondria elenae Gastaldi et al. 2018 also comes close to the specimens from Peru, but it presents slightly wider oxeas (5.1–19 µm) and is yellowish/greyish–green alive. Besides, preference is given here to the SE Pacific name, on account of biogeographic likelihood.

Halichondria (H.) prostrata might be difficult to distinguish from H. (H.) cristata , as their oxeas present overlapping sizes ( Tables 2 and 3), however, only the latter attains larger dimensions ( Sarà, 1978). Further integrative studies should help detect diagnostic characters between these two species.

Concerning the records of H. hentscheli Koltun, 1964 from the Antarctic provided by Koltun (1964) and Kunzmann (1996), which were synonymised with H. prostrata ( de Voogd et al. 2022) , we suggest their revision. Compared to H. prostrata , H. hentscheli is globular or rounded, possesses larger spicules (500– 1680 x 9–23 µm, Koltun 1964) and has been registered at deeper zones: 320–560 m ( Koltun 1964) and 500–600 m ( Kunzmann 1996) depth.

Figures

FIGURE 2. Halichondria (Halichondria) cristata Sarà, 1978. A–B, live specimens (MNRJ 11388 and MNRJ 12821, respectively); C, skeleton architecture in transverse ground section; D, skeleton architecture of the ectosome in tangential ground section; E–F, oxeas; G–H, details of E; Scale bars: A, 1 cm; B, approx. 1 cm; C–D, 500 µm; E–F, 100 µm; G–H, 20 µm; (C–H = MNRJ 11388).

FIGURE 3. Halichondria (Halichondria) prostrata Thiele, 1905. A, live specimen (MNRJ 12884); B, skeleton architecture in transverse ground section; C, skeleton architecture of the ectosome in tangential ground section; D, oxea; E–F, details of D. Scale bars: A, 2 cm; B–C, 500 cm; D, 100 µm; E–F, 20 µm.

FIGURE 7. Plicatellopsis expansa (Thiele, 1905). A–B, live specimen between 10 and 15 m (MNRJ 11248); C, live specimen at 45 m (MNRJ 12152); D, skeleton architecture in transverse ground section (MNRJ 11247); E–F, subtylostyles I & II (MNRJ 11247); G–H, subtylostyles heads of E–F. Scale bars: A–B, 2 cm; C, 2 cm; D, 500 µm; E–F, 100 µm; G–H, 20 µm.

FIGURE 9. Suberites aff. latus Lambe, 1893. A–B, live specimen of the encrusting form (MNRJ 13688); C, skeleton architecture in transverse ground section (MNRJ 13688); D–E, tylostyles I & II respectively; F–G, tylostyles heads of D–E; H–K, centrotylotes. Scale bars: A, approx. 5 cm; B, 1 cm; C, 500 μm; D–E, 100 μm; F–G, 20 μm; H–K, 10 μm.