Fenestrulina kalliste Rosso & Di Martino, 2025

Rosso, Antonietta, Di Martino, Emanuela, Donato, Gemma, Figuerola, Blanca, Gerovasileiou, Vasilis, Siddiolo, Chiara, Sinagra, Alessandro, Sanfilippo, Rossana & Sciuto, Francesco, 2025, Unlocking Mediterranean bryozoan diversity: seven new species unveiled after fixing a neotype for Fenestrulina malusii (Audouin & Savigny, 1826) (Cheilostomatida, Fenestrulinidae), ZooKeys 1254, pp. 1-74 : 1-74

Fenestrulina kalliste Rosso & Di Martino sp. nov.

Figs 1 , 15 , 22 , 23 ; Tables 1 , 3

Fenestrulina malusii (Audouin) : Rosso 1989: tables 5 a, 6 d.

Type material.

France • Holotype 1 dead ovicellate colony on a phidoloporid fragment including ~ 30 autozooids, without ancestrula on biogenic debris. Mediterranean, Liguro-Provençal basin, NW Corsica, Calvi ; R/V Catherine Laurence; Bracors- 3, Stn CL 74-12 B; 42°34'35"N, 8°41'23"E; 110 m depth; Jun. 1983; PMC.B 41.23.2.2024.a .

Diagnosis.

Fenestrulina with smooth frontal shield; scant number of pseudopores both peripherally and between the orifice and the ascopore; branching proximal spines persisting on ovicellate autozooids; prominent nodular ovicell ornamentation.

Description.

Colony encrusting, multiserial, unilaminar; interzooidal communications via two proximolateral, two distolateral and one distal pore-chambers, externally visible as elongate, elliptical windows, internally as multiporous septula.

Autozooids rounded hexagonal, distinct, separated by narrow, deep grooves (Fig. 15 A, B, F ). Upper vertical walls of autozooidal distal half slightly exposed, more evident at triple junctions (Fig. 15 C, G ), deeply sloping. Frontal shield smooth to gently nodular, moderately convex, more elevated at ascopore level. Gymnocyst present only distal and lateral to orifice. Cryptocystidean area marked by a thin raised rim, lining proximal margin of orifice, diverging laterally (Fig. 15 C, E, G, J ), forming blunt subtriangular latero-oral extensions (~ 100 μm long). Pseudopores of the frontal shield irregularly shaped, slightly infundibular, arranged in a single lateral row, usually restricted to the distal half of the autozooid, occasionally present proximally (Fig. 15 C, I ). One to two additional irregular rows of pseudopores (9–12) between orifice and ascopore. Pseudopores on a level with frontal surface, circular to irregular, with 1–4, mostly three, laterally compressed spiny processes converging centrally but not fusing at their tips (Figs 15 C – E , 23 F ). Two relatively large (50–67 μm wide), subelliptical, smoothly-rimmed cryptocystidean areas distolateral to orifice, between or distal to spines (Fig. 15 C – E ), each bearing one or two pseudopores with numerous spiny processes, exposed also in ovicellate zooids (Fig. 15 B, G – J ).

Primary orifice transversely D-shaped, hinge-line straight, lined by a smooth thin rim of calcification, ending in two denticles near proximal corners of orifice; distal rim smooth (Fig. 15 B ). Three tubular oral spines along the arched distal rim of orifice (Fig. 15 D, E ), mid spine thinner (base diameter 19–26 μm) than proximal ones (27–35 μm at the base, widening). Proximal spines bifurcating (Fig. 15 B, C arrowed, D) at ~ 50 μm from the base, maximum diameter 42 μm; proximal branch smoothly rimmed at bifurcation level, presumably the site of an articulation missing in all available material; distal branch at least up to ~ 100 μm long. Ovicellate zooids with two spines at ovicell proximal corners (Fig. 15 B, C, F – J ), distal spine concealed but persisting underneath (Fig. 15 H , black asterisk).

Ascopore relatively distal, ~ 94 μm proximal to the orifice (Fig. 15 D, E ), lumen transversely C-shaped, rim strongly denticulated, denticles simple to leaf-shaped with 3–5 smaller denticles; set in circular to transversely elliptical field of smooth gymnocyst, smooth-rimmed, flared, vertically protruding from the shield surface; often fusing with the arched proximal rim of the frontal shield when distal to an ovicell (Fig. 15 B, C, E ).

Ovicell globular, slightly elongate, prominent, narrowing proximally, obscuring the distal part of orifice, seemingly subcleithral, produced by the distal autozooid (Fig. 15 B, C, F, G ) or by a small polygonal to irregularly elongate kenozooid (Fig. 15 H – J , white asterisks). Endooecium well calcified, tuberculate-to-rugose, radial patterned, crossed by transverse crests, proximally smooth, proximal edge thin and slightly (~ 20 μm) folded upwards; with a sub-peripheral row of a dozen circular pores (~ 20 μm in diameter), barely detectable frontally (Fig. 15 A, C, F, G ), occasionally coalescing into a single elongate, 68 μm long, pore (Fig. 15 G , white arrow). Ectooecium with a thin, gently raised rim of gymnocyst lining proximal edge of distal autozooidal cryptocystidean area.

Kenozooids with a triangular (Fig. 15 I, J ) to irregularly elongate (Fig. 15 H ) visible portion, lacking pseudopores and ascopore, apparently exclusively produced in connection to ovicell formation.

Ancestrula not observed.

Etymology.

From the Greek kalliste ( καλλίστη), meaning “ the most beautiful ”, used as a noun in apposition, referring to the name given by ancient Greeks and later by J. J. Rousseau to Corsica, from where the material of this species originates. Kalliste is also the name of a marine nymph, the daughter of the sea-god Triton and Libya of Egypt.

Remarks.

Fenestrulina kalliste sp. nov. resembles F. cavernicola sp. nov., and especially F. juani , in having a markedly ornamented, elongate ovicell (OvL / OvW: 1.13). However, F. kalliste sp. nov. has smaller nodules, often aligned to form roughly radial to transverse crests, while F. cavernicola sp. nov. has spiny processes on the endooecium, and F. juani very prominent, thick and rounded nodules. Similarities with F. juani include bifurcated proximal oral spines and the protruding ascopore gymnocystal field that in F. juani is significantly more prominent, especially proximally, becoming asymmetrically cup shaped. The ascopore, in F. juani , is larger (80 × 105 μm vs 71 × 90 μm), but the lumen is smaller (20 × 39 μm vs 43 × 54 μm), giving it a different appearance. The frontal shield pattern also differs: smooth in F. kalliste sp. nov., dimpled to reticulate in both F. cavernicola sp. nov. and F. juani . Furthermore, F. juani has fewer, larger pseudopores at the autozooidal periphery and between the orifice and the ascopore, which are depressed, infundibular and pseudostellate. In contrast, F. kalliste sp. nov. has pseudopores on a level with the frontal shield, tri- to quadrifoliate, spinulose. Oral spines in periancestrular autozooids are more numerous (up to six) in F. juani . Zooids are more elongate in F. juani than in F. kalliste sp. nov. (ZL / ZW: 1.64 vs 1.23), with a proportionally smaller orifice (ZL / OL: 6.77 vs 3.76). The ovicell is also smaller in F. juani (285 × 303 μm vs 369 × 326 μm), especially in comparison with autozooidal dimensions, and proportionately wider than long. Similar but subtler size differences exist between F. kalliste sp. nov. and F. cavernicola sp. nov., with the latter species having larger autozooids but relatively smaller orifices. Bifurcated proximal spines, as in F. kalliste sp. nov., also occur in F. foveolata sp. nov., which however differs in ovicell and frontal shield texture, among other features. Some periancestrular autozooids of F. malusii also show bifurcate proximal spines and F. cavernicola sp. nov. may possess them, as suggested by spines with occasionally flattened terminations (Fig. 7 B ). This character, reported for F. juani , appears relatively common among Mediterranean species, yet globally it is known from only a few other southern hemisphere species: F. cervicornis and F. dictyota Hayward & Ryland, 1990 from Antarctica ( Hayward and Ryland 1990), and F. disjuncta (Hincks, 1885) (see Gordon 1984) and F. littoralis Gordon (2009 : fig. 13) from New Zealand. The holotype of F. kalliste sp. nov. shows two ovicell-forming kenozooids with flat, smooth surfaces lacking pseudopores and ascopores (Fig. 15 H – J ), a previously unreported character in the genus. Some colonies described by Gautier (1962) as F. malusii may belong to this species based on his mention of a bifurcate proximal pair of oral spines, or to F. foveolata sp. nov.

Habitat distribution.

To date, F. kalliste sp. nov. has been found only in organogenic sediments collected from an outer shelf setting at 110 m depth, where the Offshore Detritic Bottoms biocoenosis occurs ( Rosso 1989; Emig 2018).

Geographical distribution.

Fenestrulina kalliste sp. nov. is currently known only from the type locality, off Calvi. At least part of the material examined by Gautier (1962) might belong to this species. Most of his colonies also originate from the same geographical area of our type (Mediterranean coast of France). However, some come from other Mediterranean localities, suggesting a potential wider geographical distribution. Gautier’s collection needs revision.

Figures

Figure 1. Geographical distribution of Mediterranean Fenestrulina species (and specimens) examined in this study. Asterisks denote newly described species and the only confirmed record of Fenestrulina malusii (Audouin & Savigny, 1826), illustrated here with Savigny’s original drawing (reproduced from d’Hondt 2006) shown on the left. Type material is shown for each species, except for F. malusii, for which the neotype (upper image) and a colony fragment from Ile-Rousse Bank, NW Corsica (lower image) are figured. Large symbols indicate type localities; small symbols mark additional occurrences. Symbol colours correspond to species as follows: red = F. malusii; bright green = F. cavernicola sp. nov.; vivid pink = F. communis sp. nov.; pale blue = F. foveolata sp. nov.; blue = F. granulosa sp. nov.; olive green = F. kalliste sp. nov.; dark green = F. ovata sp. nov.; purple = F. variorugosa sp. nov.; lilac = Fenestrulina sp. Note: in areas with multiple records, only one symbol is used to represent the locality.

Figure 7. Fenestrulina cavernicola Rosso & Di Martino, sp. nov. holotype PMC. B 38.23. 2.2024. a, Agios Vasilios cave, Lesvos Island, Aegean Sea. A. Group of ovicellate and non-ovicellate autozooids. Note the dimpled texture of the frontal shield; B. Group of ovicells with rugose endooecium, widely separated from the rudimentary ectooecial rim and proximolaterally indented by two oral spines, which occasionally appear flattened (arrowed); C. Distal part of an autozooid showing the orifice with two lateral denticles and three distally placed oral spines. Lateral lappets and distal areas of cryptocystidean calcification are developed, while the gymnocyst just around the orifice is poorly expressed; D. Periancestrular autozooids and ancestrula regenerated as a kenozooid with a few pseudopores and a central ascopore with an apparently smooth rim. Multiple regeneration events are evident; E. Cluster of damaged and regenerated autozooids, with intramural budding forming in directions even opposite to the original polarity; F. Detail of an ascopore and several trifoliate or quadrifoliate pseudopores; G. Non-ovicellate autozooid. Scale bars: 500 μm (A, D); 200 μm (B, E, G); 100 μm (C); 50 μm (F).

Figure 15. Fenestrulina kalliste Rosso & Di Martino, sp. nov. holotype PMC. B 41.23. 2.2024. a, Calvi, NW Corsica, Liguro-Provençal basin. A. General view of the colony; B. Ovicellate autozooids. Note the tuberculate-to-wrinkled appearance of the ovicells, the bifurcate spines (white arrows), and the exposed cryptocystidean areas lateral to the ovicells (black arrow); C. Ovicellate autozooid with one bifurcated oral spine still in place (arrowed). Note the prominent rim of the ascopore field and the ovicell pores distally occluded by secondary calcification; D. Autozooid with three spines and exposed cryptocystidean areas (arrowed); E. Regenerated autozooid with orificial cryptocystidean area (arrowed); F. Colony portion showing variability in ovicell ornamentation; G. Differently inclined ovicells showing the prominence and morphology of their proximal rim. A particularly large ovicell pore (white arrow) and cryptocystidean areas distal to the orifice (black arrow) are indicated; H. Broken twin ovicells in two contiguous autozooids formed by the same kenozooid (white asterisk); distal spine still evident in one case (black asterisk); exposed cryptocystidean areas are black arrowed; lateral view of the kenozooidal ovicell depicted in I and J (white arrow); I, J. Overview and detail of an ovicell formed by a distal kenozooid (asterisks). Arrow: exposed cryptocystidean area. Scale bars: 1 mm (A); 500 μm (B); 200 μm (C, F, G – J); 100 μm (D, E).

Figure 22. Geographical distribution of all known records of Fenestrulina in the Mediterranean, plotted against current summer Sea-Surface Temperatures (data from IFREMER-LOPS Data Visualization Portal https://syntool.ifremer.fr/, accessed Sept. 2024). An asterisk marks the probable origin of the original material of F. malusii. Large dots: collection sites of specimens with confirmed species attribution; small dots: records of putative F. malusii requiring taxonomic revision, but with known provenance; open ellipses: sites, covered by dedicated monographs, from which Fenestrulina species are absent.

Figure 23. Comparison of pseudopores in the studied species of Fenestrulina. A. F. malusii; B. F. cavernicola sp. nov.; C. F. communis sp. nov.; D. F. foveolata sp. nov.; E. F. granulosa sp. nov.; F. F. kalliste sp. nov.; G. F. ovata sp. nov.; H. F. variorugosa sp. nov.; I. Fenestrulina sp. Scale bars: 100 μm.