Ianthella flabelliformis ( Linnaeus, 1759 )

Van Soest, Rob W. M., 2025, Typification of Porifera described in the 10 edition of Linnaeus’ Systema Naturae, volume II, 1759, Zootaxa 5638 (1), pp. 1-65 : 21-25

Ianthella flabelliformis ( Linnaeus, 1759)

Figs 10A–F , 11A–B , 12 .

Spongia flabelliformis Linnaeus, 1759: 1348 , sp. 4; Pallas 1766: 380, sp. 226 [also Boddaert 1768: 478 and Wilkens 1787: 217)]; Linnaeus 1767: 1296, sp. 2; Houttuyn 1772: 430; Esper 1790 a: pl. XIII, 1794 (text): 213; Gmelin in Linnaeus 1791: 3817, sp. 2; Lamarck 1814: 380; Lamouroux 1816: 57.

Ianthella flabelliformis ; Gray 1869: 50; Poléjaeff 1884: 37, pl. I; Von Lendenfeld 1888: 23; 1889: 696, pl. 47 figs 1–4, 6, pl. 48 figs 1–4, pl. 49 figs 1–3; Bergquist & Kelly-Borges 1995: 155, pl. 4a–b, pl. 5a–b, text-figs. 2a–b (not: Ridley 1884: 392 = I. basta )

Verongia flabelliformis ; Ehlers 1870: 11.

Original description: ‘ Spongia flabelliformis rigidiuscula, fibris capillaribus densissime reticulatis’ (i.e. a stiff flabelliform sponge, densely reticulated with capillary fibers).

Type material: Unknown. I propose as neotype a fragment of a specimen recently collected at Parry Shoals, 35 nm West of Bathurst Island, Northern Territories, Asutralia , 11.2113°S 129.707°E, depth 18–20 m, flat sand, coll. SCUBA, 14 August 1987, sufficiently close to the localities cited in the pre-1758 and early post-1758 references. The specimen is kept in the Queensland Museum, Brisbane, reg. nr. G310149, courtesy of Dr Merrick Ekins. (https://collections.qm.qld.gov.au/objects/SM12317/ianthella-flabelliformis). This neotype designation is motivated especially in order to avoid confusion with closely similar species of the genus Ianthella .

Molecular sequence: 28SrRNA obtained by Erpenbeck et al. (2024).

Remarks: Linnaeus (1759) did not give references, but in his 1753b ‘Species Plantarum’ he referred to Boerhaave (1727), Linnaeus (1737b) and Van Royen (1740) for references. Boerhaave’s (1727: 6): ‘Keratophyton majus nigrum, fibris tenuioribus elegantissime & densisissime reticulatum’ (i.e. large black ‘Keratophyton’, finely and densely reticulated with finer fibers). Linnaeus (1737b: 480, sp. 5): ‘ Spongia flabelliformis , caule teretiuscula, diseo compresso-plano vix diviso’ (i.e. flabelliform sponge, smooth stem, compressed-flat, scarcely divided); Van Royen (1740: 522), and Linnaeus (1753b: 1170) gave the same definition as Linnaeus (1759).

Pallas (1766: 380, sp. 226) (translations in Dutch by Boddaert 1778: 478 and in German by Wilkens 1787: 217 (sp. 4) fig. 70, here reproduced in Fig. 10D ) gave a new definition: ‘ Spongia rigida rara subatra flabelliformis plana rotundaque’ (i.e. a stiff, rare, flat, round fan-shaped sponge) and provided many new references, and this time with several images. He cited Linnaeus 1737b and 1759 as well as Boerhaave 1727 (with same definition) and Van Royen 1740; also Petiver (1709: pl. XXXII fig.1, ‘Rete Philippinense nigrum, telis quadrangulis’ (i.e. Philippine network, black with square meshes), here reproduced in Fig. 10A ); Rumphius (1750: 208, pl. 80 fig. 1 ‘Flabellum marinum Aruense’, here reproduced in Fig. 10B ); and Seba (1758: 183, pl. 95 figs 2,4 ‘Alcyonium irregulare, rigidum, membranaceum & cellulosum’ (i.e. irregular Alcyonium, rigid, membranous and cellular), here reproduced in Figs 10C 1–2 ).

Houttuyn (1772: 430) cited all the references given above and discussed differences with Spongia basta and Spongia ventilabrum .

Esper [1791b: pl. XIII, (here reproduced in Fig. 10E ), 1794: 213 (text)] gave a complete history with all references cited above. Von Lendenfeld (1888, 1889) reviewed the species and compared it with Ianthella basta ( Pallas, 1766) . Because no images were provided by Linnaeus (1737b, 1753b and 1759) and Van Royen (1840), Von Lendenfeld (1888) argued that the references these sources provided were insufficient to discriminate this species from the similar Ianthella basta ( Pallas, 1766) . Only after Pallas described the latter species with additional references the differences became apparent: I. basta is thin-bladed, often folded, and smooth, while I. flabelliformis has a knotty surface (cf. Poléjaeff 1884: pl. I, here reproduced in Fig. 10F ; see also Bergquist & Kelly-Borges 1995). Von Lendenfeld decided that Linnaeus’ (1759) concept of Spongia flabelliformis could also include Spongia basta and for that reason he assigned authorship to Gray (1869).

Later authors, e.g. Bergquist & Kelly-Borges (1995) assigned the species to Pallas, because he distinguished it from Ianthella basta . However, even though he expanded the knowledge of the species, Pallas used Spongia flabelliformis in the sense of Linnaeus (1759). Linnaeus’ name has priority (1759) and unless his species is demonstrated as distinctly different from Pallas’ Spongia flabelliformis , Linnaeus’ authorship is warranted.

Species diagnosis: (after Bergquist & Kelly-Borges 1995: 155, pl. 4a–b, 5a–b, text-figs 2a–b). Lamellate, stalked, thick fan, up to 1 m high and 1.5 cm thick, with the surface raised into irregular ridges, up to 0.5 cm high. Colour greenish yellow in situ (rarely blueish), turning purple in alcohol and black in dried condition. Consistency firm. Skeleton a semi-regular network of fibres, 120–500 µm in thickness oriented in one plane with primary fibres loosely fasciculated, and interconnecting fibres forming irregular polygonal meshes. The elevated ridges are formed by fasciculated primary fibres extending from the network and coalescing to form rounded knobs with microconulose endings. The knobs may coalesce to form meandering ridges. The fibres have a strongly laminated bark and a pith occupying 10% of the fibre thickness.

The present species is the type of the genus Ianthella Gray, 1869 . It differs from the other species already known in the 18 th century, Ianthella basta ( Pallas, 1766) , in having a surface with irregular elevated ridges and knobs, whereas the surface of I. basta has uniformly ladder-like patterns of microconules. Dr Ekins provided an in situ image of the neotype in Fig. 11A , an on deck image in Fig. 11B .

Distribution ( Fig. 12 ): Australian waters, Indonesia, Philippines, Papua New Guinea.

Figures

FIGURE 1. Pages reproduced from A. Van Royen 1740 (pp. 521–522) treating Spongia species. Note that only 10 species were listed (Spongia fluviatilis was omitted compared to Linnaeus 1753b cf. Fig. 2) and the order of presentation is different.

FIGURE 2. Pages reproduced from C. Linnaeus’ 1753b ‘Species plantarum’ (pp. 1169–1171) treating Spongia species. Note that the genus was assigned to the Cryptogamia order Algae, but curiously S. lacustris and S. fluviatilis were assigned to order Fungi. Note also, that according to ICZN art. 3.2. no names published before January 1 1758 enter zoological nomenclature, making the Spongia name combinations of 1753 unavailable.

FIGURE 10. Images assigned to Ianthella flabelliformis by various authors (originally as Spongia). A. Petiver’s ‘Rete Philippense nigrum, telis quadrangulis duplicatis’, (1709: pl. XXXII fig. 1); B. Rumphius’ ‘Flabellum marinum Aruense’ (1750: pl. 80, fig. 1); C 1–2. Seba’s ‘Alcyonium irregulare, rigidum, membranaceum & cellulosum’ (1758: pl. XCV figs. 2 and 4); D. Wilkens’ ‘Fächerschwamm’ (1787: pl. XX fig. 70); E. Esper’s Spongia flabelliformis ‘Der Wedelförmige Saugschwamm’ (1790a: pl. XIII); F. Poléjaeff’s Ianthella flabelliformis (1884: pl. I).

FIGURE 11. Neotype specimen of Ianthella flabelliformis (Linnaeus, 1759 as Spongia), QM G310149, designated herein.A. in situ at Parry Shoals, 35 nm West of Bathurst Island, Northern Territories, Australia, 11.2113°S 129.707°E, depth 18–20 m, flat sand, coll. SCUBA (photo Merrick Ekins); B. ditto, on deck.

FIGURE 12. Distribution records of Ianthella flabelliformis (L.), dots are WPD data, squares are OBIS data dots are WPD data (image downloaded from the World Porifera Database, cf. De Voogd et al. 2023).