Ancorina Schmidt

Kelly, Michelle & Sim-Smith, Carina, 2012, A review of Ancorina, Stryphnus, and Ecionemia (Demospongiae, Astrophorida, Ancorinidae), with descriptions of new species from New Zealand waters, Zootaxa 3480, pp. 1-47 : 4

Genus Ancorina Schmidt

Ancorina Schmidt, 1862: 51 .

Sanidastrella Topsent, 1892: 18 .

Type species: Ancorina cerebrum Schmidt, 1862: 51 (by subsequent designation).

Diagnosis. Ancorinidae with a conspicuous ectosome, large triaenes (orthotriaenes, plagiotriaenes, dichotriaenes, protriaenes, and anatriaenes), and oxeas. The ectosome can be up to several mm thick, with layers of fibrillar collagen deposited at the surface and above the ectosome/choanosome boundary, the latter of which often appears dark and granular. Triaenes radiate in dense discrete brushes within the ectosome, cladomes outermost, often extending beyond the sponge surface, rendering it harsh and hispid. Oxeas diverge obliquely towards the surface in loose tracts, but have a confused orientation deeper within the choanosome. Microscleres include small euasters (chiasters, tylasters, oxyasters), and a larger oxyaster category that is commonly present within the choanosome. Short irregular sanidasterhabds and/or sanidasters are concentrated within a surface layer of the ectosome (emended from Uriz 2002).

Remarks. Uriz (2002) commented that, following Sollas (1888) and various early authors, she also considered Ancorina to be separate from Ecionemia , and that the former was characterised by the possession of sanidasters (defined as having a linear shaft from which rays arise perpendicular to the axis along the entire shaft), while the latter possessed a microrhabd (defined here as a straight acanthose monaxonic microsclere). Uriz conceded, however, that the difference between sanidasters and microrhabds is not always clear because it was sometimes difficult to differentiate between spiny microrhabds and sanidasters with reduced actins. We find that the ‘sanidasters’ of our New Zealand Ancorina are different from those of other genera; they are short and highly irregular, frequently with an almost euasterose centrum, or an elongated thick axis rather than a long linear axis as in a true sanidaster. The rays may be reduced to short acanthose spines as in A. diplococcus , and A. stalagmoides (see Fig. 4 C, H), in which the microsclere takes the appearance of a spiny rhabd with a slightly restricted middle region (dumbbell-shaped), or the microsclere may have two to six short thick acanthose strongylote rays or clubs (see Fig. 4 M) as in A. bellae sp. nov. The difference between these and the microrhabds of Ecionemia is that the latter are grain-shaped and uniformly roughened (acanthose), not spined (see Fig. 5 E, K). In order to reduce confusion between triaene-containing species with true sanidasters such as in Stryphnus and Asteropus , we call the microscleres of these Ancorina ‘sanidasterhabds’ in recognition of their sanidasters-like rays, but short microrhabd-like overall shape.

Uriz (2002) implied in her revision of the diagnoses of Ancorina and Ecionemia , that Ancorina could be distinguished from Ecionemia on the presence of oxyasters in the former, and a lack of oxyasters in the latter. Species of Ancorina possess a category of small euasters, reported in the literature variously as chiasters, oxyasters, oxyspherasters, stronglyotylasters, or tylasters. We have observed that many species, including various specimens of the type species, A. cerebrum Schmidt (e.g. A. cerebrum, Marenzeller (1889) ; Stelletta boglicii Schmidt, 1862 ; S. immunda Schmidt, 1862 ), have a second category of larger euaster, an oxyaster , confined to the choanosome. In A. multistella Lendenfeld, 1907 , these may reach 135 µm diameter (see Table 3). Within the genus Ecionemia , only E. densa Bowerbank, 1873 is described as having oxyasters, but these are in the same size category as the other small euasters. Thus we agree with Uriz (2002), but have expanded her diagnosis of Ancorina to state that there are usually two size categories of oxyaster , as opposed to there usually only being a single (small) category in Ecionemia .

We also concur with Uriz (2002) comment about the difficulty of differentiating between the sanidasterhabds of some Ancorina species, and the acanthormicrorhabds of Ecionemia species. Accordingly, in our emendment of the diagnoses of the two genera, we emphasise the clear differences in the architecture of the ectosome as being critical in determining the generic diagnosis. Microsclere form and size, whether sanidasterhabds, acanthomicrorhabds, and the presence of small or large oxyasters, are complementary characters that serve to confirm the diagnoses.

Figures

FIGURE 4. Megascleres and microscleres of New Zealand species of Ancorina: Ancorina diplococcus, NIWA 62048: A. dichotriaene, scale = 500 µm; B. oxyaster I, scale = 10 µm; C. dumbbell-shaped sanidasterhabds, scale = 5 µm. Ancorina stalagmoides, NIWA 49896: D. protriaene, scale = 500 µm; E. prodichotriaene, scale = 500 µm; F. oxyaster I, scale = 10 µm; G. oxyaster II, scale = 5 µm; H. dumbbell-shaped sanidasterhabds, scale = 5 µm. Ancorina bellae sp. nov., NIWA 62005: I. prodichotriaene, scale = 500 µm; J. anatriaene, scale = 200 µm; K. oxyaster I, scale = 20 µm; L. oxyaster II, scale = 10 µm; M. cruciform sanidasterhabds, scale = 5 µm. Ancorina globosa sp. nov., NIWA 76782: N. dichotriaene, scale = 500 µm; O. oxyaster I, scale = 20 µm; P. spheraster-shaped oxyaster II, scale = 4 µm; Q. dumbbell-shaped sanidasterhabds, scale = 6 µm.

FIGURE 5. Megascleres and microscleres of New Zealand species of Ecionemia: Ecionemia alata, NIWA 52981: A. plagiotriaene, scale = 500 µm; B – C. anatriaenes, scale = 100 µm; D. chiaster with recurved spines, scale = 5 µm; E. acanthomicrorhabd, scale = 5 µm. Ecionemia novaezealandiae, NIWA 62156: F. plagiotriaene, scale = 500 µm; G. anatriaene, scale = 100 µm; H. promesotriaene, scale = 100 µm; I. chiaster with recurved spines, scale = 5 µm; J. spherochiaster, scale = 5 µm; K. acanthomicrorhabd, scale = 5 µm.