Scrupocaberea maderensis (Busk, 1860)

Scrupocaberea maderensis (Busk, 1860) View in CoL

Figure 15 View FIGURE 15

v. 1860 Scrupocellaria maderensis Busk , p. 280. v. 2014 Scrupocaberea maderensis (Busk) ; Vieira, Spencer Jones, Winston, Migotto and Marques, p. 18, fig. 15A–C.

Figured material. PMC EDM-Collection J.H.B.127a, sample 19019 ( Figure 15A–C, H–I View FIGURE 15 ), sample 19016 ( Figure 15D–E View FIGURE 15 ), and sample 19147 ( Figure 15F–G View FIGURE 15 ); Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Description. Colony erect with relatively narrow (270–350 µm) branches; branches rectilinear to slightly curved, biserial transitioning to triserial at bifurcations, flat; articulating nodes not observed. Autozooids distinct, separated by shallow grooves, rounded rectangular to club-shaped, elongate (mean ZL/ZW 2.68), arranged in two longitudinal, alternating series. Proximal gymnocyst smooth, extensive; cryptocyst nodular to finely granular (granules 7–11 µm in diameter), slightly depressed, relatively wide proximally, tapering laterally, absent distally. Opesia pear-shaped, occupying slightly less than half of the frontal surface (mean OpL/ZL 0.41) with beaded proximolateral margins; two spines on the inner and three on the outer distolateral corner, 7–18 µm in diameter at the base, the proximalmost pair larger; spines visible also in ovicellate zooids. Scutum very robust, originating laterally from the inner side, attached at about two-thirds of opesia length, covering the proximal portion entirely and leaving a semicircular orifice distally, kidney-shaped, truncated at the top, with a robust attachment structure measuring 55–77 µm in diameter. Adventitious avicularia, small, drop-shaped, occurring as two types: a single (often absent) frontal avicularium at the distal termination of the gymnocyst adjacent to the opesia, leaning towards the median axis of the branch, positioned atop a raised cystid c. 90 µm long, with acutely triangular rostrum directed distolaterally on either side; a constant lateral avicularium positioned on a conical cystid 100–120 µm long, with acutely triangular hooked rostrum directed laterally; both types with complete crossbar. Ovicells globular, occupying the entire proximal gymnocyst of the distal zooid; ooecium smooth with an almost completely calcified ectooecium apart from a small, circular to transversely elliptical fenestra, 25–30 µm long by 25–40 µm wide, located medioproximally, exposing the endooecium. Opesia of ovicellate zooids with denticulated distal margin. Dorsal side occupied by triangular vibracula with a long, slightly curved, deep setal groove; a shallow zigzag median furrow corresponding to zooidal boundaries; each vibraculum with a large, circular radicular pore measuring 25–35 µm in diameter, located proximally on the outer side.

Measurements (µm). ZL 439±12, 411–452 (1, 13); ZW 164±9, 146–178 (1, 13); GymL 221±19, 197– 270 (1, 14); CryL 50±6, 38–60 (2, 19); OpL 183±11, 157–198 (1, 16); OpW 100±10, 80–113 (1, 16); AvL (frontal) 50±2, 48–53 (2, 6); AvW (frontal) 27±1, 26–29 (2, 6); AvL (lateral) 50±2, 48–53 (1, 16); ScuL 120±9, 109–140 (2, 17); ScuW 76±6, 64–84 (2, 17); OvL 189±2, 187–190 (1, 3); OvW 143±13, 128–152 (1, 3); VibrL 164±11, 147–181 (1, 7); VibrW 96±6, 84–103 (1, 7).

Remarks. Scrupocaberea maderensis , originally described from the Azores, has since been recorded worldwide, including Japan ( Tilbrook, 2006). It has been recognized as a complex of species by Vieira et al. (2014), who distinguished two additional species from specimens previously identified as S. maderensis by Harmer (1926). This suggests that further records might reveal additional species upon re-analysis. However, when comparing our specimens with the syntype figured in Vieira et al. (2014, figure 15A–C), no significant differences were observed in morphological traits or size, indicating that the North-Pacific specimens are similar to those from the Atlantic. Despite this, the geographical distance raises doubts about their conspecificity. Vieira et al. (2014) described the cryptocyst of S. maderensis as smooth with beading around the opesial margin. However, in the images of the syntype and also in our specimens, the cryptocyst appears nodular to finely granular. Differences between S. maderensis and the congener in the same samples, S. contraria sp. nov., are discussed in the Remarks section above.