Trikentrion muricatum (Pallas, 1766)

Soest, Rob van, Carballo, Jose Luis & Hooper, John, 2012, Polyaxone monaxonids: revision of raspailiid sponges with polyactine megascleres (Cyamon and Trikentrion), ZooKeys 239, pp. 1-70 : 32-38

Trikentrion muricatum (Pallas, 1766) Figs 17 A–D, 18 A–E, 19 A–D, 20 A–D

Spongia muricata Pallas 1766: 389 (referring to Seba 1734-65, volume III pl. 99 fig. 7, Ghana); Esper 1794: 185, pl. 3 (Ghana).

(not: Linnaeus 1759: 1348; 1767: 1298 = unrecognizable; nec: Lamarck 1814: 448 = Raspailia hispida , cf. Topsent 1932: 107).

Unnamed branched tuberculated sponge; Ellis, 1766: pl. 11 fig. F (West Africa).

? Spongia echidnea Lamarck, 1814: 448 (West Africa).

Trikentrion muricatum ; Ehlers 1870: 6; Carter 1879: 293, pl. 27 fig. 13 (Ghana); Burton 1956: 133, 142 (Ghana); Hooper 2002: 499, figs 18A-G.

Plectronella papillosa Sollas 1879: 17, pls 4-5.

? Ptilocaulis echidnaeus ; Topsent 1932: 108, pl. III fig. 3.

Remarks.

The identity of the sponge named Spongia muricata by Pallas, which is assumed to be the type species of Trikentrion , is not straightforward. The first use of the name combination stems from Linnaeus (1759: 1348), who described it as:

S. ramosissima, poris cylindricis subulatis prominentibus aequalibus multifidis hispidis, without further indication of where it had been collected or by whom. The Latin name muricata is generally considered to mean spined (after the name of a mollusk ( Murex ) yielding a purple dye, cf. Brown 1985), for sponges a hardly distinguishing feature. The description speaks of cylindrical pores, which is quite vague, and this character does not occur in any specimen discussed in this paragraph and below. Pallas (1766: 389), employed the name combination also, but indicated and described the sponge figured in Seba’s (1734-1765) volume 3 pl. 99 fig. 7 as representing his Spongia muricata . Pallas did not refer to Linnaeus’ name, nor did his description remind in any aspect of Linnaeus’ description. Seba’s figure is here reproduced in Fig. 17A, and Pallas’s description in Fig. 17C. Pallas also quoted Elmina on the coast of Guinea (now Ghana) as the locality of the specimen based on Seba’s information. In the same year (or perhaps one year before), Ellis (1765-1766), pictured a similar sponge (a branched tuberculated sponge here reproduced in Fig. 17B), stating that it originated from the Cape Coast Castle in Africa (which could very well be the same locality Elmina), but not naming it. In his 1767 edition, Linnaeus again described Spongia muricata , replacing the first word of the 1759 edition, Spongia ramosissima by the text S. foraminulata ramosissima angulata tenax, followed by the same words as previously (reaffirming the unrecognizable shape of the sponge). He also added that it originated from O. Aethiopico (Indian Ocean). He now gave three sources for his record of this species, viz. Mus. Tessin 118, plate II figure 1, Seba’s volume 3 plate 99 fig. 7, and Pallas’ record. Finally, Gmelin in Linnaeus 1788: 3821, admits that the species is from Guineae littorea , quoting a.o. Pallas (1766) and Linnaeus (1767), but remarkably omitted any reference to Linnaeus (1759). Linnaeus’ and Pallas’ ( Seba’s) specimens of Spongia muricata have never been identified in later collections (but see below), and their identity remains a matter of speculation. In 1794, Esper extensively described Spongia muricata and his figure is here reproduced in Fig. 17D. This time, the specimen, stated to be from Guinea , from cliffs near Elmina (= Ghana), was still extant in the collections of the University of Erlangen (Germany) in 1870, when Ehlers revised some of Esper’s specimens (Ehlers, 1870). He detected the triactine spicules and erected the genus Trikentrion for it. His description included some measurements of the spicules: oxeas 354-414 × 16 µm, and polyactines, with basal cladi 95 µm and lateral cladi 72 µm, which data conform closely with those presented below for the species. However, since Ehlers’ redescription, the whereabouts of the Esper material is unknown and it must be assumed lost. Lamarck (1814: 448) misinterpreted Spongia muricata and his material was assigned to Raspailia hispida (Montagu, 1818) by Topsent (1932: 107). Possibly, Spongia echidnea Lamarck, 1814 is a junior synonym of Spongia muricata Pallas, because the redescription and figured specimen of Topsent (1932: 108, as Ptilocaulis echidnaeus ) reminds rather strongly of it. However, Topsent fails to mention the presence of polyactine spicules.

To conclude: the identity of Spongia muricata is not unequivocal, primarily due to the unrecognizable description of Linnaeus (1759) and the likelihood that he used the name for an unknown species from the Indian Ocean. Pallas’ description in combination with Seba’s figure make it likely that his Spongia muricata indeed is what we now know as Trikentrion muricatum , but uncertainty reigns due to the fact that only Esper’s, not Pallas’, material was shown to possess the synapomorphy of the polyactine spicules. It appears highly necessary to fix Spongia muricata as a Trikentrion , by assigning a neotype. In the absence of any topotypical fresh material of the species we are forced to choose dry old collection material.

A likely candidate is the assumed type of Trikentrion muricata housed in the Natural History Museum, London, BMNH 1872.10.19.1 (see Fig. 18A), with schizotype ZMB 7160, on the basis of which Carter (1879) redescribed and illustrated the species Trikentrion muricatum , and which subsequently formed the basis of the Systema Porifera entry of the genus and its type species. This is not likely to be Seba’s specimen, nor Esper’s because the locality data (though from Ghana as well) do not indicate Elmina. In addition to this specimen, the Natural History Museum collections incorporate a schizotype of Spongia muricata , Coast of Guinea, BMNH 1954.2.20.93, which appears unimportant for the present choice of neotype because it is not a Trikentrion , but an unidentified species of Axinella Schmidt, 1862.

The choice of a neotype again is complicated due to a recent discovery in the collections of the Naturalis Biodiversity Center at Leiden (NBC) of four old collection specimens, RMNH Por. 306 and 309, and ZMA Por. 02545 and 02546, which are sufficiently similar to Seba’s and Esper’s plates to raise the suspicion that they could belong to one of the original specimens of Spongia muricata .

RMNH Por. 309 (see Fig. 18B) is labeled Raspailia xerampelina (Lmk)? type (Spongia --- Lmk) without further information, and this specimen bears an overall strong likeness to Seba’s plate. RMNH Por. 306 (see Fig. 18C) is labeled Raspailia hispida (Mont.) type van Spongia muricata Lmk, Mus. Parijs, Kust van Guinée (translation: type of Spongia muricata Lamarck, from the Paris Museum, Coast of Guinea). If the specimen is compared to the plate of Spongia muricata of Esper one is compelled by the overall likeness of the two (though it is not an exact likeness). ZMA Por. 02545 (see Fig. 18D) is labeled Halichondria echidnaea Lmk no. 55 Kust van Guinea, ZMA Por. 02546 (see Fig. 18E) is labeled Halichondria echidnaea Lam / muricata Esper fide Lamouroux no. 62 Kust van Guinea. Both ZMA specimens bear some resemblance to Seba’s and Esper’s plates.

The skeleton and spicules of all five specimens conform with the descriptions of Ehlers (1870) and Carter (1879).

The reason for the names on the labels of the specimens of the NBC and the referral to the Paris Museum is explained in Holthuis (1995): during the French occupation in 1795 of the Republic of Holland in the Napoleontic period, Dutch collections were confiscated and relocated to the Paris Museum. Some time after the end of the emperorship of Napoleon in 1815, negotiations between The Netherlands and France resulted in a donation of specimens, notably duplicates from Lamarck’s collection, to the then founded Rijksmuseum of Natural History at Leiden. Dozens of sponge specimens labeled with Lamarck’s names are incorporated in the RMNH collections, but because the redescription of Lamarck’s sponges by Topsent (1931, 1932, 1933) was initiated after the transfer of specimens to Leiden, there is often little correspondence between the identities of the MNHN and RMNH specimens bearing labels with the same original Lamarck names. Topsent (1932) identified Lamarck’s Spongia muricata as Raspailia hispida , and this was duly taken over by past curators of the Leiden specimens, who apparently were unaware of the discrepancies between the Paris and Leiden specimens. It is possible, that the Lamarck specimen redescribed in Topsent (1932 as Raspailia hispida ), is not Lamarck’s original specimen, because this may have ended up in the Leiden or Amsterdam collections.

In view of the uncertain history of the NCB specimens and the more precise data available for the Natural History Museum, London specimen, we here designate BMNH 1872.10.19.1 as the neotype of Spongia muricata , the type species of the genus Trikentrion .

It is a pleasure to be able to announce that material of Plectronella papillosa Sollas, 1879, since long known to be a junior synonym of Trikentrion muricatum through its excellent description by Sollas, but otherwise never redescribed, has been discovered in the collection of the Bristol Museum and Art Gallery, in the form of 2 slides labeled No. 30 Ah.200.1, 200.3 (see Fig. 19B), containing cross sections of the skeleton and dissoluted spicules. We can confirm that Plectronella papillosa is a junior synonym and that details in the slides conform closely to those of Trikentrion muricatum (see Fig. 19 C–D).

Material examined.

Neotype (designation herein): BMNH 1872.10.19.1 from Volta River, Fantee, Ghana, presented by Gov. Ussher. Schizotype ZMB 7160 of the same;

RMNH Por. 306, Spongia muricata Lamarck, Coast of Guinea;

RMNH Por. 309, Spongia xerampelina Lamarck, no further data;

ZMA Por. 02545, 02546, Halichondria echidnaea / muricata Lamarck, coast of Guinea;

BMAG Ah 200.1, 200.3, 2 slides labeled Plectronella papillosa no. 30, no further data.

Description.

Wide basal holdfast upon which are erected groups of cylindrical branches, more or less in one plane, each branch usually with one or two dichotomous secondary branches, often also with anastomosing branches. Size of neotype (Fig. 18A) 13.5 × 12 × 5 cm of the whole group of branches, diameter of individual branches 1-1.5 cm. Sollas’ specimens (Fig. 19A as Plectronella papillosa ) were described as being 20 × 20 cm, with branch diameter 2-3 cm. The other specimens are similar in size, but slightly smaller. Surface densely covered with broad, laterally flattened papillae, 1-4 mm in size (reminding of the surface projections of Ptilocaulis Carter, 1883). In some specimens the papillae are partially abraded (e.g. RMNH Por. 306, see Fig. 18C) giving the sponge a less striking aspect. Consistency (dry) hard, incompressible, crumbly. No live color has been reported in the literature, but color plates of Seba (Fig. 17A) and Esper (Fig. 17D) show a light orange brown color.

Skeleton (Fig. 20A): predominantly a wide-meshed reticulation of tracts of robust smooth oxeas, with little axial and extra-axial specialization. The polyactines are common in peripheral regions. No longer or smaller peripheral styles have been found in any of the examined specimens.

Spicules: Oxeas, polyactines, trichodragmas.

Choanosomal ‘true’ oxeas (Figs 19C, 20B, B1, not to be confused with diactinal polyactines), fat, fusiform, tapering gradually to sharp points, overall size (of all specimens examined) 222 –376.2– 528 × 13 –19.9– 31 µm, in the neotype: 287 –351.5– 432 × 13 –17.2– 26 µm.

Polyactines (Figs 19D, 20C), predominantly three-claded Y-shaped, rarely T-shaped, occasionally diactinal, with prominent hook-like spines on the basal clade (undeveloped spicules with smooth basal clade), and mucronate or nipple-like endings on many of the lateral cladi; overall size of basal clade (of all specimens examined) 78 –111.7– 156 × 12 –19.2– 27 µm, lateral cladi 42 –67.2– 84 × 12 –16.7– 27 µm, of neotype: basal clade 78 –100.2– 118 × 12 –19.4– 25 µm, lateral cladi 58 –69.2– 84 × 13 –16.3– 21 µm.

Trichodragmas (Fig. 20D), straight or sinuous, overall size (of all specimens examined) 57 –82.0– 102 × 4 –9.7– 18 µm, of neotype: 63 –87.8– 102 × 9 –12.8– 18.

Distribution.

Tropical West Africa. Type from 'Elmina, Guinea’ (Pallas, 1766; Esper, 1794), now situated in Ghana. Further specimens were reported mostly from Ghana (neotype (Carter, 1879): Volta; Burton, 1956: Gold Coast), or locality was unknown (Sollas, 1879), or more general (coast of Guinea).

Ecology.

Depth range: no definite data, but probably shallow water, growing on rocks.

Discussion.

The species must have been of common occurrence off the coast of Ghana in 18th century as there are a fair lot of specimens available from that age and region in several natural history museums. Curiously, no fresh material is known to exist, so the species remains ill-known. Trikentrion muricatum differs substantially from all other Trikentrion species described below in the lack of peripheral styles. Further differences are robust oxeas, up to twice as long and thick as those of the two other oxea-bearing species ( Trikentrion laeve Carter, 1879 and Trikentrion flabelliforme ), while the three remaining species ( Trikentrion helium , Trikentrion catalina and Trikentrion africanum sp. n.) lack the oxeas entirely.