Scutoplites virgulus, Reverter-Gil & Souto & Berning, 2025

Scutoplites virgulus sp. nov.

( Figs 6 View FIGURE 6 , 7 View FIGURE 7 ; Tables 2–4 View TABLE 2 View TABLE 3 View TABLE 4 )

Scrupocellaria marsupiata : d’Hondt 1975: 556 (in part) (figs 14–16?).

? Notoplites marsupiatus View in CoL : d’Hondt & Schopf 1985: 913 (part).

Not Notoplites marsupiatus View in CoL : d’Hondt & Schopf 1985: 913 (part). [= S. batmani sp. nov., see below]

Material examined. Holotype: MNHN-IB-2008-7576 : Biaçores stn. 245, 40º57’N, 22º16’W, 4270 m, 14 Nov. 1971 ( d’Hondt 1975, as Scrupocellaria marsupiata ) ( Fig. 6 A, E, F, G View FIGURE 6 ) GoogleMaps . Paratypes: MNHN-IB-2017-1894 (separated from MNHN-IB-2008-7586; Fig. 6 B, D View FIGURE 6 ), same information as for the holotype, a small branch fragment, dry GoogleMaps ; MNHN-IB-2017-1905 (separated from MNHN-IB-2008-7569; Fig. 6 C, H View FIGURE 6 ), same information as for the holotype, a branch fragment with ovicellate zooids, dry GoogleMaps . Additional material examined: MNHN-IB-2008-11964: Atlantis II , cruise 24, stn. 126, 39º37’– 39º37.5’N, 66º44’– 66º47’W, 3806 m ( d’Hondt & Schopf 1985, as Notoplites marsupiatus ) ( Fig. 7 A, F View FIGURE 7 ) GoogleMaps . MNHN-IB-2008-11966: Atlantis II , cruise 31, stn. 155, 0°03’0’’S, 27°48’0’’W, 3730–3783 m ( d’Hondt & Schopf 1985, as Notoplites marsupiatus ) ( Fig. 7 B–E View FIGURE 7 ). GoogleMaps

Etymology. From the Latin virgula (rod, stick), reflecting the long internodes without signs of branching. While it is likely that branching does occur, it is remarkable that it is absent from the relatively long internodes.

Description. Colony erect, presumably dichotomously branching but several long (> 6.4 mm) and straight internodes do not show signs of bifurcation, attached to the substrate by rhizoids. Branches formed by two series of alternating autozooids, opening on one side only. Autozooids elongate, slightly narrower and tubular proximally, with the distal half turned outwards alternatingly to right or left. Distal third of autozooid occupied by an oval membranous area, covered proximally by a convex flabelliform scutum, slightly longer than wide, attached to the inner proximal angle of orifice; marginally merging with the circum-opesial gymnocyst except on the inner side, with about 6–10 narrow and variably long radial fissures, lacking on the inner edge, leaving a wide imperforated central area. Rarely a spine lateral to orifice, just distal of attachment of scutum; a second small one in the proximal outer angle of the orifice and a third in the outer distal angle of the autozooid. All spines broken in the material examined and frequently lacking. Orifice wider than long. Operculum thickly sclerotised.

Adventitious avicularia of two kinds: one small, situated proximolateral to orifice, with the triangular mandible obliquely directed proximally and outwards; another small one on a raised cystid just proximally to scutum, its triangular mandible directed proximally. Mandibles in both avicularia hinged on inconspicuous condyles.

Ovicell large, globular, prominent, longer than wide, resting on the proximal part of the distal autozooid. Surface somewhat uneven and with a proximomedian circular fenestra, the proximolateral ooecial margins reaching towards mid-distance of lateral orifice rim, ovicell opening well arched above orifice.

An ancestrula was not observed.

Remarks. As for the previous species, the description of S. virgulus sp. nov. is based on several fragments that are not very well preserved. Despite having ovicells, the fragments lack dichotomies. Therefore, the description cannot be complete. An apparent budding of a new branch shown in Fig. 7B and D View FIGURE 7 originates from rhizoids on the abfrontal side of the proximal branch. Nonetheless, the remaining characters are significant enough to differentiate this species from the others treated in the present work.

Scutoplites virgulus sp. nov. mostly resembles S. clausus n. comb. but differs in several key characters: in S. virgulus sp. nov. the scutum is almost circular, only slightly longer than wide and with longer fissures, whereas in S. clausus n. comb. the scutum is clearly longer than wide and has shorter fissures. The lateral avicularia are visible in frontal view in S. virgulus sp. nov. but they are displaced basally and not visible in frontal view in S. clausus n. comb. The ovicell is clearly longer than wide in S. virgulus sp. nov. whilst it is slightly wider than long in S. clausus n. comb. Finally, S. virgulus sp. nov. has fewer distal spines.

Scutoplites marsupiatus n. comb. has more numerous and longer fissures, a larger lateral avicularium, a much longer ovicell, and the orifice is as long as wide. Scutoplites saojorgensis n. comb. has a scutum that is wider than long, with longer and more numerous fissures, a larger lateral avicularium, the orifice is displaced towards the outer autozooid margin, and it has a triangular fenestra in the ovicell. Finally, in S. reverteri n. comb. and S. hamartia sp. nov. the scutum is very different, with longer digital branch prolongations, among other differences.

Part of the material here described as S. virgulus sp. nov. was originally reported as Scrupocellaria marsupiata by d’Hondt (1975) but, as noted above, several species were combined under this name in that work. The specimens imaged by d’Hondt (1975: figs 14–16), are quite similar to S. virgulus sp. nov. and show a dichotomy, which is unfortunately lacking in the material studied here. However, these figures are not completely representative and, furthermore, d’Hondt (1975) did not include any comment on the origin of the figured sample, or samples, while the work includes nine different localities for Scrupocellaria marsupiata that are geographically spaced far apart from each other. Therefore, we cannot unquestionably ascribe those figures to the present species.

D’Hondt & Schopf (1985) reported N. marsupiatus from two distant Atlantic localities: hundreds kilometres east of New Jersey at 3806 m depth (MNHN-IB-2008-11964), and in the equatorial Mid-Atlantic Ridge at 3730–3783 m depth (MNHN-IB-2008-11966) (see above additional material examined). While two of the fragments from the latter locality belong to S. batmani sp. nov. (MNHN-IB-2022-574, see below and Fig. 10C View FIGURE 10 ), the remaining material is morphologically quite similar to the type material of S. virgulus sp. nov., and also occurs in depths of over 3700 m. Although the biometric data are somewhat larger, they generally maintain the same proportions (see Tables 3 View TABLE 3 , 4 View TABLE 4 ). In sample MNHN-IB-2008-11966, some autozooids have up to four stout distal spines ( Fig. 7C View FIGURE 7 ), whereas in others these are absent ( Fig. 7B View FIGURE 7 ). Autozooids with spines probably correspond to the first generations of autozooids from the zone of astogenetic change, with an ancestrula (currently unknown) that is perhaps vase shaped with a circle of spines, as in other Candidae . Despite the considerable distance separating the three localities ( USA, Azores and equatorial Mid-Atlantic Ridge), in the absence of morphological differences we have to assign all the material to the same species. The species description given above is, therefore, exclusively based on the type specimens, which are from a single station north of the Azores (4270 m depth). In the case of S. batmani sp. nov. (see below) we also found the same species in three similarly distant locations. Nonetheless, it is clearly necessary to collect new material and conduct molecular studies to verify the identifications, but when working with material from deep waters, as is the case, this will probably be a very difficult endeavour.