Exechonella verrucosa (Canu and Bassler, 1927)

Exechonella verrucosa (Canu and Bassler, 1927) View in CoL

Figure 24 View FIGURE 24

v. 1927 Coleopora verrucosa Canu and Bassler , p. 6, 42, pl. 1, fig. 7.

v. 1929 Coleopora verrucosa Canu and Bassler ; Canu and Bassler, p. 267–268, pl. 20, fig. 4, pl. 26, fig. 9.

v. 2017 Exechonella verrucosa (Canu and Bassler) ; Cáceres-Chamizo, Sanner, Tilbrook and Ostrovsky, p. 56, fig. 23.

Figured material. PMC EDM-Collection

J.H.B.131a, sample 19074 ( Figure 24A–D View FIGURE 24 ) and sample 19125 ( Figure 24E–F View FIGURE 24 ); Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Description. Colony encrusting. Autozooids distinct, separated by deep grooves, oval to rhomboidal, slightly longer than wide (mean ZL/ZW 1.13).

Frontal shield slightly convex, wrinkled, tessellated, evenly and densely punctured by over 40 minute, circular foramina, c. 15 µm in diameter; foramina centrally located within a larger funnel-shaped gymnocystal rim, measuring between 30–40 µm in diameter; often, rims of 2–3 foramina fusing together, forming distinctive reniform to trifoliate clusters adorned with tubular, hollow, spike-like frontal projections, 75–125 µm long, 25–40 µm in diameter at the tip; projections randomly distributed across the frontal shield, with about 6–8 per zooid in the specimens examined; numerous circular marginal pores, roughly 15 µm in diameter, distributed around zooidal periphery. Primary orifice subcircular, slightly wider than long, surrounded by a short, collar-like peristome; stout, triangular condyles, 35–40 µm long by 40–45 µm wide, medially directed, placed at two-thirds of orifice length, separating the orifice into equally wide anter and poster, with anter occupying two-thirds and poster one-third of orifice length. Peristome externally pustulose, internally smooth to slightly wrinkled, forming a sloping shelf proximally, developing spiny processes around its rim; eight such processes counted in the single zooid in which they were all preserved, with the lateral one showing a bifurcated structure. Avicularia present on the rims of lateral or proximal foramina producing tubular projections, characterized by a distinctive nipple-like structure with a central pore.

Measurements (µm). ZL 1159±96, 1059–1251 (2, 3); ZW 1028±59, 975–1092 (2, 3); OL 275±3, 273– 278 (2, 3); OW 322±26, 298–349 (2, 3); PeL 221±55, 182–260 (2, 2).

Remarks. To date, Exechonella verrucosa is unequivocally known only from the Philippines. Records from other geographical areas have been reassigned to new species in an effort to clarify the E. verrucosa species-complex (Cáceres-Chamizo et al., 2017). Due to the limited availability of material, consisting of only a few fragments with one or two zooids each, it is challenging to observe morphological variation. However, the key characteristics of our specimens fit the updated description of E. verrucosa , which appears to be the closest match among those described within this genus, also in terms of size, number and distribution of foramina. Notable differences we have observed compared to the Recent type specimens include the absence of well-defined longitudinal striations on the inner surface of the peristome; instead, only wrinkles concentric to the proximal orifice margin have been observed. Additionally, adventitious kenozooids associated with the avicularia are also absent in our specimens.