Leuconia dohrni Chagas & Cavalcanti 2021, comb. nov.
Creators: name: Chagas, Cléslei
name: Cavalcanti, Fernanda F.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Calcarea
Baerida
Baeriidae
Leuconia
Leuconia dohrni

description: Leuconia dohrni (Sarà, 1960) comb. nov.
Amphoriscus dohrni Sarà, 1960
Citations and synonymies: Amphoriscus dohrni Sarà, 1960: 26; Klautau, Cavalcanti & Borojevic 2017: 109; Cóndor-Luján et al. 2019: 1825.
Type material: SZN POR207, holotype —not analysed by the present work. Ischia Island, Gulf of Naples, Tyrrhenian Sea; depth 40 m.
Type locality: Ischia Island, Gulf of Naples, Tyrrhenian Sea.
Morphology: As explained above, the type material (SZN POR207) could not be analysed, and additional samples were not available or could not be located. According to the original description (Sarà 1960), the specimen has an ellipsoidal shape and apical osculum without fringe of trichoxeas. No data about the aquiferous system is provided, and the lack of illustrations of the skeletal or histological organisations prevented any inferences from being made.
Anatomy: The cortical skeleton is formed by triactines and giant tetractines, which point the apical actines to the middle of the sponge body (Sarà 1960). Microdiactines are present along the whole skeleton, but Sarà (1960) emphasised they are more abundant at the atrial skeleton, which is also formed by small and particular tetractines (see remarks below).
Spicules (according to the original description):
Cortical tetractines: Giant, actines have similar length (700–1200/70–120 μm).
Cortical triactines: Smaller than the cortical tetractines (170–350/15–35 μm).
Atrial tetractines (see remarks below): They have a particular (harpoon) shape. Apical (70–80/ 7–9 μm) and unpaired (55–70 μm) actines are considerably longer than the paired ones (20–35 μm).
Microdiactines: Lanceolate (60–70/4 μm).
Remarks: Due to the small size of the type specimen (<1cm), it could not be loaned, and microscope slides could not be prepared by the current staff of the Stazione Zoologica Anton Dohrn di Napoli (Andrea Travaglini, personal communication). Nevertheless, based only on the original description, we figured out that (1) important characters typical of Amphoriscus were not reported along the description of this species, such as the syconoid aquiferous system and the inarticulate skeleton formed by the apical actines of the cortical tetractines and the unpaired actine of the subatrial spicules; and (2) the shape of the small atrial tetractines, of which “la forma è molto caratteristica” (Sarà 1960), suggesting that they are pugioles. These spicules correspond to small harpoon—(or dagger-) shaped spicules present in the order Baerida (Borojevic et al. 2002; Alvizu et al. 2018, 2019). Besides the presence of pugioles, the description provided by Sarà (1960) contains other characters found in the definition of Baerida: the presence of cortical large and giant spicules (triactines and tetractines, respectively, in the case of A. dohrni), and the presence of microdiactines abundant in the atrial skeleton (although it is not clear if they are more abundant than the atrial pugioles). Therefore, based on these features, there is no support for keeping the species inside the genus Amphoriscus, and we propose to transfer it to Baerida.
According to Van Soest et al. (2021), Baerida is formed by four families: Baeriidae Borojevic, Boury-Esnault & Vacelet, 2000, Petrobionidae Borojevic, 1979, Trichogypsiidae Borojevic, Boury-Esnault & Vacelet, 2000, and Lepidoleuconidae Vacelet, 1967. Among the families mentioned above, only Baeriidae and Petrobionidae include pugioles in their composition (Borojevic et al. 2002; Alvizu et al. 2019). Petrobionidae has a basal calcareous skeleton of calcite. This family is monotypic, and Petrobiona massiliana Vacelet & Lévi, 1958 does not resemble “ A ”. dohrni, in which the basal skeleton is absent (Borojevic et al. 2002). Baeriidae includes four genera: Leuconia Grant, 1833, Eilhardia Poléjaeff, 1883, Lamontia Kirk, 1895, and Leucopsila Dendy & Row, 1913. However, only Leuconia and possibly Lamontia are pugiole-bearing genera. The latter is characterised by having diactines perforating the cortex and microdiactines throughout the choanoskeleton, characters that were not reported for “ Amphoriscus ” dohrni (Sarà 1960; Borojevic et al. 2002). Since this species does have atrial pugioles, we decided to allocate it within Leuconia¸ despite the absence of sagittal triactines in the atrium. We therefore highlight the need for a taxonomic revision of Leuconia and the entire order Baerida, echoing recent suggestions from Alvizu et al. (2018, 2019).
description: Published as part of Chagas, Cléslei & Cavalcanti, Fernanda F., 2021, Partial taxonomic revision of Amphoriscus Haeckel, 1870 (Porifera: Calcarea) with description of A. decennis sp. nov., pp. 39-68 in Zootaxa 5061 (1) on pages 63-64, DOI: 10.11646/zootaxa.5061.1.2, http://zenodo.org/record/5642287