Spongilla lacustris ( 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 : 42-45

Spongilla lacustris ( Linnaeus, 1759)

Figs. 23A–C , 24A–B

Spongia lacustris Linnaeus, 1759: 1348 , sp. 10; Linnaeus 1767: 1299, sp. 15; Houttuyn 1772: 463; Gmelin in Linnaeus 1791:

3825, sp. 15; Esper 1791c: pl. XXIII, 1794: 233 (text, in part); Bosc 1802: 147; Manconi & Pronzato 2000: 90, figs 2a–b,

4a–c, 5–6. Spongilla ramosa Lamarck, 1816: 100 ; Gray 1821: 353. Ephydatia lacustris ; Lamouroux 1816: 7. Spongilla lacustris ; Johnston 1842: 110; Annandale 1911: 67; Penney & Racek 1968: 9 (with comprehensive list of synonyms);

Manconi & Pronzato 2000: 90; Pronzato & Manconi 2001: 38; Manconi & Pronzato 2002: 926, figs 2–7.

Original description: ‘ Spongia repens fragilis, ramis teretibus obtusis’ (i.e. creeping fragile sponge with delicate blunt-ending branches).

Type material: Lectotype LH 1295.2, paralectotype LH. 1295.1, type locality Småland, South Sweden, approximate coordinates 59.82°N 14.67°E, cf. discovery of the Linnaean Herbarium specimens and redescription by Manconi & Pronzato 2000: 90, figs 2a–b. An earlier neotype designation by A.A. Racek in Penney & Racek (1968: 11, specimen RMNH Por. 1053, collected by D.van der Kuyl in the Vlaardingsevaart near Vlaardingen, The Netherlands, approximate coordinates 59.9°N 4.34°E, 17 September 1941) was made void by the discovery of Linnaeus’ material in the Linnaean Society by Manconi & Pronzato ( ICZN art. 75.8).

Remarks: The original description was copied from Linnaeus (1737a: 372, with remarks that it grows on objects on the bottom of lakes and found in the Torne river, on the border between Norway, Finland and Sweden) and Van Royen (1740: 523). Linnaeus (1745: 390) remarked that it was commonly found from in Lake Möckeln, Sweden). An additional reference for this species, ‘It.scan.’, was given by Linnaeus (1753b: 1171), possibly referring to his Lapland expedition, but I could not confirm this from any Linnaean work. It is clear that Linnaeus himself was intimately familiar with the species (as well as his Spongia fluviatilis ) from observations during his Swedish travels. A further pre-1758 reference is Ray (1686: 81, as ‘ Spongia ramosa fluviatilis’ in the river Yare, Norfolk, UK),

Pallas (1766) did not list this species as valid, although he discussed its status in the remarks of Spongia fluviatilis (currently Ephydatia fluviatilis , cf. below) (see Pallas 1766: 385; also, Boddaert 1768: 484, and Wilkens 1787: 221).

Linnaeus (1767: 1259) and Gmelin in Linnaeus (1791: 3825) did not add further sources. Both concluded that the species was found in Sweden and England.

Esper (1791 c, 1794) discussed the species and gave two illustrations, pl. XXIII (here reproduced in Fig. 23C ) and pl. XXIIIA ( Esper, 1794) (here reproduced in Fig. 23D ), the latter suggested to be perhaps conspecific with Pallas’ S. fluviatilis , but he recognized only a single species. For his S. lacustris he repeated several Linnaeus’ and Pallas’ references, e.g. Loesel (1703) and Ruppius (1721), but these concern Ephydatia fluviatilis , see below, because these references were given by Linnaeus only for Spongia fluviatilis .

Species diagnosis: (after Manconi & Pronzato 2000: 90, figs 2a–b). From an initial encrusting form the species usually develops an arborescent bush-like growth, in extreme cases up to 1 m in diameter. Branches are circular in outline and tend to grow upright ending pointedly and develop side branches, but there are also frequently repent branches from which side branches grow upwards. Surface optically smooth, but in detail is irregular and hispy, with only few flush oscules. Consistency fragile and soft. Colour green, yellow-green or whitish. Ectosomal skeleton consists of brushes of spicules, but these do not form a tangential crust. Choanosomal skeleton irregularly anisotropic, in thin crusts isotropic. Spicule tracts are multi- or paucispicular interconnected by paucispicular tracts, both bound with ample spongin. Spicules are smooth fusiform oxeas. Microscleres are scattered curved small acanthoxeas, 25–178 x 2–8. The gemmules, up to 789 µm in diameter, have either gemmuloscleres which are lightly or strongly bent and bear hooked spines, 21–130 x 1–10 µm, or are ‘naked’ (without gemmulosleres).

The image of the preserved lectotype from Manconi & Pronzato (2000) is here reproduced in Figs 23A– B ). An in situ image from Oegstgeest, The Netherlands (52.17329°N 4.450464°E) of the species is provided in Fig. 24B .

This species was designated as the type species of genus Spongilla Lamarck, 1816 by Annandale (1911), which is slightly problematic as Lamarck did not describe the species (he listed only three species, Spongilla pulvinata Lamarck, 1816 , Spongilla friabilis Esper, 1791 , and Spongilla ramosa ). However, he mentioned the name Spongia lacustris under his ‘Observations’ preceding the descriptions of the species, which leave little doubt that Lamarck considered Linnaeus’ S. lacustris as one of the members of the genus.

Distribution ( Fig. 24 ): Common in Europe (cf. detailed map in Pronzato & Manconi (2001: 39), with records from North America and Palearctic Asia.

Figures

FIGURE 23. Images assigned to Spongilla lacustris by various authors. (originally as Spongia). A. lectotype LH 1295.2 designated by Manconi & Pronzato 2000: 90, photo Linnean Herbarium, https://linnean-online.org/13967/#?s=0&cv=0; B. paralectotype LH 1295.1 designated by Manconi & Pronzato 2000: 90, photo Linnean Herbarium, https://linnean-online.org/ 13966/#?s=0&cv=0; C. Esper’s Spongia lacustris (1791: pl. XXIII); D. Esper’s Spongia lacustris varietas (1794: pl. XXIIIA), which may represent Spongia fluviatilis.

FIGURE 24. Spongilla lacustris. A. in situ image from Oegstgeest, The Netherlands, 52.17329°N 4.450464°E (photo N.J. de Voogd); B. Distribution of Spongilla lacustris (L.), image downloaded from the World Porifera Database, cf. De Voogd et al. 2023 (only an outline of the actual distribution).