Leucosolenia corallorrhiza
Creators: name: Lavrov, Andrey
name: Ekimova, Irina
name: Schepetov, Dimitry
name: Koinova, Alexandra
name: Ereskovsky, Alexander
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Calcarea
Leucosolenida
Leucosoleniidae
Leucosolenia
Leucosolenia corallorrhiza

description: Leucosolenia corallorrhiza (Haeckel, 1872)
(Figs 7–10; Table 5)
= Ascortis corallorrhiza Haeckel * 1872 = Sycorrhiza corallorrhiza * Haeckel * 1870 = Auloplegma corallorrhiza Haeckel * 1872 = Leucosolenia cf. variabilis % Alvizu et al. 2018 * Lavrov et al. 2018). = Leucosolenia variabilis %Lavrov and Ereskovsky 2022 * Lavrov et al. 2022* Melnikov et al. 2022).
= Leucosolenia complicata %Ereskovsky et al. 2017a).
Type material: Type material is not known.
Type locality: Haeckel based his description on one specimen from Norway and one from Greenland * without designating the type material % Rapp 2015).
Material studied: Altogether 177 specimens. Molecular data— 177 specimens * external morphology— 177 specimens * skeleton organization— two specimens %WS11650* WS11653)* spicules %SEM)— five specimens %WS11649* WS116450* WS11653* WS11657* WS11658)* cytology % TEM)— six specimens %WS11631* WS11632* WS11634* WS11635* WS11636* WS11637) %Supporting Information* Table S1).
External morphology: Cormus formed by basal reticulation of tubes* from which erect oscular tubes and long diverticula arising. Sponge bear from one to multiple* slightly curved oscular tubes* with or without short* lateral diverticula in the basal part. Oscular tubes gradually narrow to oscular rim* possessing short* spicular crown % Fig. 7A * B). Surface minutely hispid or echinate. Coloration of living and preserved specimens greyish white % Fig. 7A).
Spicules: Diactines % Fig. 8A * B). Curved* lanceolate diactines* mean length 179 µm* mean width 6 µm % Table 5)* slightly curved with lanceolate outer tip* variable in size* smooth or with few small spines at lanceolate tip % Fig. 8B).
Triactines % Fig. 8D). T-shaped sagittal %mean angle 142.9°)* unpaired actines usually shorter than paired %mean length: 70.5 µm—unpaired* 82.7 µm—paired) % Table 5)* rarely equal. Actines equal in width %mean width: 6.5 µm—unpaired* 6.5 µm—paired) % Table 5).
Tetractines % Fig. 8C). T-shaped sagittal %mean angle 151.4 °)* unpaired actines shorter than paired or equal %mean length: 68.8 µm—unpaired* 80.7 µm—paired* 22.9 µm—apical) % Table 5). All actines equal in width %mean width: 5.6 µm—unpaired* 5.8 µm—paired* 5.5 µm—apical) % Table 5). Apical actine curved and smooth.
Skeleton: Skeleton of oscular tubes predominantly formed by both tri- and tetractines* while in cormus tubes tetractines rare %Fig.
7C* D). In oscular tubes* spicules constitute organized array with their unpaired actines directed toward cormus and oriented more or less in parallel to proximo-distal axis of oscular tube % Fig. 7C). In cormus tubes* spicule network appears completely disordered % Fig. 7D). Both populations of diactines forming small oscular crown up to 60 µm and cover tubes’ surface* orienting in different directions and extending outside by lance-shaped tip % Fig. 7B).
Cytology: Body wall* 8.4–12 µm thick* three layers: exopinacoderm* loose mesohyl* and choanoderm % Fig. 9A * B; Supporting Information* Table S2). Flat endopinacocytes located only in the distal part of oscular tube %oscular ring) replacing choanocytes. Inhalant pores scattered throughout exopinacoderm* except the oscular ring area.
Exopinacocytes non-flagellated* T-shaped* rarely flat % Fig. 9C). External surface covered by glycocalyx. Cell body %height 7–10.5 µm* width 4.3–5.5 µm)* containing spherical to oval nucleus %diameter 3.1 µm)* submersed in mesohyl. Cytoplasm with specific spherical electron-dense inclusions %0.2–0.4 µm diameter) % Fig. 9C).
Endopinacocytes non-flagellated flat cells* size 16.8 µm × 2.2 µm % Fig. 9D). External surface covered by glycocalyx. Nucleus %2.1 µm × 1.6 µm) spherical to oval with nucleolus. Cytoplasm with specific spherical electron-dense inclusions %0.2–0.5 µm diameter) % Fig. 9D).
Choanocytes flagellated trapeziform or prismatic %height 8.2 µm* width 4.1 µm) % Fig. 9E). Flagellum surrounded by collar of microvilli. Characteristic pyriform nucleus %2.6 µm × 4.1 µm) in apical position. Cytoplasm with phagosomes and small vacuoles. Choanocytes united by specialized intercellular contacts similar to septate junctions* but has no basal membrane % Fig. 9E).
Porocytes tubular cylindrical %height 5.5 µm* width 4.2 µm)* connecting external milieu with choanocyte tube % Fig.
9F). Nucleus pyriform %diameter 3.1 µm)* containing nucleolus. Cytoplasm with phagosomes* small vacuoles* and spherical electron-dense inclusions identical with inclusions of exopinacocytes.
Sclerocytes amoeboid* size 8.7 µm × 3.5 µm % Fig.10A). Nucleus usually oval or pear-shaped %diameter 2.5 µm)* containing single nucleolus. Well-developed Golgi apparatus and rough endoplasmic reticulum.Cytoplasm usually with phagosomes and/or lysosomes. During spicules’ secretion* sclerocytes form groups of three to six cells* connected by septate junctions % Fig. 10A).
Amoebocytes of different shape %from oval to amoeboid) without special inclusions* size 5.7 µm × 4.7 µm % Fig. 10B). Nucleus spherical %diameter 2.9 µm)* sometimes with nucleolus.
Granular cells oval* size 9 µm × 5.5 µm. Regularly distributed* numerous cells* usually located under choanocytes % Fig. 10C – E). Nucleus in peripheral position* spherical %diameter 2.5 µm). Cytoplasm with oval* electron-dense inclusions %size 0.9–2.7 µm × 1.1–3.7 µm) % Fig. 10E). Inclusion content homogenous or granulated. Often found in stage of degradation* cytoplasm completely filled with two to four large* oval inclusions* with highly osmiophilic granulated content % Fig. 10F).
Myocytes are fusiform cells* size 22 µm × 2.7 µm; distributed in the mesohyl mostly in the oscular ring. Nucleus usually oval %2.9 µm × 1.6 µm)* without nucleolus % Fig. 10G). Cytoplasm includes mitochondria* ribosomes* small vesicles* and* most importantly* the presence of cytoplasmic myofilaments of 19– 12 nm in diameter % Fig. 10G). Myofilaments form bundles %0.37–0.16 µm diameter) that are located along the long axis of the cell.
One morphotype of bacterial symbionts in mesohyl. Bacteria numerous* rod-shaped with double-cell wall* diameter 0.3– 0.33 µm* length 3.0–5.6 µm %Figure 10H* I). Nucleoid region electron-dense with irregular network of filaments.
Distribution: Boreal-Arctic species. Molecular identity confirmed for Greenland and the White Sea % Alvizu et al. 2018). In the White Sea* it is the most abundant species* inhabiting kelps and hard substrates in low intertidal and subtidal zones up to 15– 20 m depth.
Reproduction: In the White Sea* specimens collected in late October contained early oocytes; specimens collected in January/February contained fully developed larvae.
Remarks: In the White Sea* this species was initially identified as Leucosolenia variabilis * based on its external morphology %Lavrov et al. 2018). In addition* most of our sequences for this species were identical to LSU and SSU sequences downloaded from the GenBank under the name L. variabilis. Regarding morphology* the spicular characters of our specimens were different from the original description of L. variabilis %Haeckel 1872)* but partly fit the description given in Minchin %1904). The main differences relate to diactine morphology: in our specimens* there is a single type of curved lanceolate diactines. In L. variabilis sensu Haeckel %1872)* two diactine populations were found: the first has small* strait trichoxea* and the second has normal* curved* lanceolate diactines. Minchin %1904) found connectivity in size among small and long diactines* and suggested that they represented a single type of diactine* which was overlooked by Haeckel. Since our specimens possess only a single diactine population* it might support Minchin’s conclusions. However* Leucosolenia variabilis sensu Minchin %1904) is a species complex* since he designated Leucosolenia somesii a junior synonym of L. variabilis * while morphological and molecular data supported its identity as a distinct species %see below; see also: van Soest et al. 2007). Therefore* the diagnosis provided by Minchin %1904) should not be taken into consideration.
To address the possible ontogenetic variation of diactines* we studied the type material L. variabilis from the collection of BMNH % syntype BMNH-1910.1.1.421). The spicular characters of this specimen perfectly fit the original description made by Haeckel %1872)* with two diactine types* tri- and tetractines of equal abundance* and unpaired actines in tri- and tetractines always shorter than paired ones. On the other hand* specimens in our material possess only a single diactine type* and tetractines are rare. Therefore* the species from the White Sea is not L. variabilis * despite its molecular similarity to specimens* placed in the GenBank under the name L. variabilis.
Another species* that is characterized by a single diactine type and short unpaired actines in tri- and tetractines is Leucosolenia corallorrhiza * which was designated a valid species in the most recent morphology-based revision of Greenland calcareous sponges %Rapp 2015). Haeckel %1872) described this species under the name Ascortis corallorrhiza * addressing a small proportion or absence of tetractines* small and thick triactines with short* unpaired actines. Diactines are curved* lance-shaped %Haeckel 1872: 74). This feature is characteristic of samples from the White Sea* although in our specimens* some diactines bear small spines on their lance-shaped tips. These spines are hardly visible with light microscopy and may be overlooked* even during SEM studies. Since we could not study the morphology of specimens whose sequences were obtained from GenBank* and morphological data for those specimens are absent in the respective paper % Alvizu et al. 2018)* we designate our specimens from the White Sea as Leucosolenia corallorrhiza * until both morphological and molecular confirmation for specimens from the type localities become available. Also* neotype designation for this species is necessary to establish the type material; specimens for this purpose should be collected in the type locality. It should be mentioned that our specimens demonstrate minor differences in coloration from the original description [L. corallorrhiza is brown according to Haeckel %1872)]. Also* actines in tri- and tetractines are thicker in the initial description %widths ~15 µm in Haeckel 1872; up to 12.5 µm in our material % Table 5); up to 10.7 µm in Rapp 2015)* but this difference may be associated either with ontogenetic or intraspecific variation* or different measurement procedures and equipment.
From Leucosolenia variabilis this species differs by spicular characters: in L. variabilis * there are two types of diactine* while there is only one type of diactine in L. corallorrhiza. Leucosolenia corallorrhiza never forms a large* massive cormus. Leucosolenia corallorrhiza also differs from other species in cytological characteristics %Supporting Information* Table S2): in contrast to L. complicata * the mesohyl of L. corallorrhiza includes not only amoeboid cells* but also rather numerous granular cells* regularly distributed in the body wall; in contrast to L. variabilis * L. corallorrhiza has larger granular cells* no spherulous cells* and only one morphotype of rod-shaped symbiotic bacteria.
description: Published as part of Lavrov, Andrey, Ekimova, Irina, Schepetov, Dimitry, Koinova, Alexandra & Ereskovsky, Alexander, 2024, The complex case of the calcareous sponge Leucosolenia complicata % Porifera: Calcarea): hidden diversity in Boreal and Arctic regions with description of a new species, pp. 876-914 in Zoological Journal of the Linnean Society 200 on pages 888-893, DOI: 10.1093/zoolinnean/zlad104, http://zenodo.org/record/11248861