Cribellopora? fissurata, Martino & Rosso & Taylor & Chiu & Fujita & Kitamura & Yasuhara, 2025

Cribellopora? fissurata sp. nov.

Di Martino, Rosso, and Taylor

Figure 50 View FIGURE 50

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Type material. Holotype PMC. B68. 29.7.2024 a, sample 19088; Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Etymology. Latin, meaning fissured, referring to the deep slit-like sinus of the orifice.

Diagnosis. Lacernid with exposed lateral gymnocyst forming a well defined boundary with the frontal wall, and a slightly raised rim below the orifice; frontal shield mostly imperforate except for 1–2 rows of peripheral pores, seemingly stellate; orifice semicircular with deep slit-like sinus, 6–7 distolateral spines in autozooids, four in ovicellate zooids; ovicell small and globular, uniformly pseudoporous with ooecial pseudopores circular.

Description. Colony encrusting, multiserial, unilaminar. Autozooids distinct, separated by deep grooves, rounded hexagonal, longer than wide (mean ZL/ZW 1.39). Gymnocyst smooth, visibly exposed laterally and around the orifice, forming a well-defined, slightly elevated boundary with the frontal wall; gymnocystal rim extending laterally to the orifice, aligning with the proximalmost pair of oral spine bases and lying at a short distance below the oral sinus. Frontal shield flat to slightly convex, smooth, mostly imperforate except for one or two rows of pseudopores along the zooidal lateral margins, the outermost row adjacent to the gymnocystal rim; pseudopores with a seemingly stellate pattern, 12–24 µm in diameter, situated within funnel-shaped depressions. Orifice semicircular, almost as wide as long with rectangular condyles spanning the entire length of the proximal margin of the orifice; sinus deep and slit-like; 6–7 oral spine bases in autozooids, 13–17 µm in diameter, the largest being the proximalmost pair; four spines retained in ovicellate zooids. Ovicell hyperstomial, globular; ooecium uniformly pseudoporous; pseudopores circular, 4–9 µm in diameter. Pore-chamber windows visible distally and distolaterally at colony edge, elliptical, 27–49 µm long by 9–21 µm wide.

Measurements (µm). ZL 415±87, 330–536 (1, 4); ZW 299±24, 267–324 (1, 4); OL 94±3, 92–98 (1, 4); OW 98±4, 94–101 (1, 4); SinL 27±2, 25–29 (1, 4); OvL 196±23, 171–217 (1, 3); OvW 201±12, 188–212 (1, 3).

Remarks. This species is tentatively assigned to Cribellopora because of its similarity with C. souleorum Dick, Tilbrook, and Mawatari, 2006 from Hawaii. These two species share characteristics such as autozooids with a lateral gymnocyst forming a well-defined boundary with the frontal wall, and a frontal shield mostly imperforate except for peripheral rows of seemingly stellate pores. They also share the semicircular orifice surrounded by smooth gymnocystal calcification with a narrow, deep sinus and long condyles flanking it, along with robust spine bases, and a globose ovicell with minute simple pores (see Dick et al., 2006, figure 13A– C and this paper Figure 50 View FIGURE 50 ). The primary difference between the two species is in the shape of the sinus. In C.? fissurata , the sinus is deep and slit-like with parallel sides, whereas in C. soleorum it is shallower and drop-shaped. Souto et al. (2010) questioned the generic assignment of C. soleorum after examining the type specimen of C. simplex Gautier, 1957 , the type species of Cribellopora . Cribellopora simplex has a frontal shield uniformly perforated by compound (i.e., cribrate) pseudopores that are also present distally to the orifice, no visible lateral gymnocystal walls, and evanescent spines. Ovicells in C. simplex are flattened frontally with a central umbo, and imperforate except for a row of pseudopores arranged in an arc on its distal slope. Among the species currently assigned to the genus Cribellopora , there is significant morphological variability. For instance, C. connata (Ortmann, 1890) from Japan has uniformly porous ooecia with the same cribrate pseudopores as those on the frontal (Arakawa, 2024), while species like C. divisopora ( Waters, 1887) , C. napi Gordon, 1989b and C. siri Gordon, 1989b from New Zealand have imperforate ooecia except for a row of stellate or simple marginal pores (Gordon, 1989b). The Miocene European species C. latigastra (David, 1949) also displays this pattern (David and Pouyet, 1974). The Atlanto-Mediterranean C. trichotoma (Waters, 1918) appears more closely related to C. simplex . Although initially synonymized by Gautier (1962), they were later proven to be distinct (Souto et al., 2010). Cribellopora trichotoma has a wider sinus, stouter spine bases, and a more densely perforated ooecium. Cribellopora constellata Winston, 2005 features a frontal shield with numerous stellate pores, also found distally to the orifice and scarcely below it. This species also lacks oral spines and has an imperforate ooecium. The Miocene species C. hluchovensis Zágoršek, 2010 and C. trasoni Zágoršek, 2010 share an absence of oral spines and of marginal ooecial pores, although preservational issues, especially in the former species, might have obscured this characteristic (Zágoršek, 2010).

Within Lacernidae , Arthropoma , Lacerna Jullien, 1888 and Phonicosia Jullien, 1888 are other genera bearing a general resemblance to C.? fissurata sp. nov., which however does not fit well into any of them. The shape of the sinus resembles that of some species of Arthropoma and Phonicosia , which differ in the arrangement of frontal pseudopores (present also distally to the orifice and more uniformly on the frontal except for limited central imperforate areas) and the development of the lateral gymnocyst. Additionally, variations in ovicell structure distinguish these genera. Arthropoma species may have a smooth, imperforate endooecium and a partially calcified ectooecium proximally, while ovicells in Phonicosia are smooth and imperforate except for marginal pores. Moreover, Phonicosia can have frontal adventitious avicularia. Lacerna has a frontal shield similar to C.? fissurata sp. nov., with the lateral gymnocyst forming a sharp boundary and pseudopores predominantly limited to zooidal margins. However, the orifice typically displays a wider sinus, and the ovicell bears only marginal pores. This frontal structure, characterized by lateral gymnocystal walls forming a sharp boundary, as well as the arrangement of pseudopores, are reminiscent of species of Fenestrulina , a closeness supported by molecular sequencing data (see Orr et al., 2022).

While the similarities between our species and C. souleorum , along with their distinctive features, may suggest the need for a new genus within Lacernidae , we refrain from such action due to the scarcity of available specimens and preservational issues which impede the comprehensive observation of species variability and obscure pore shape, despite our certainty that they are not compound. Consequently, we choose provisionally to assign this species to Cribellopora based on its resemblance to C. souleorum .