Conescharellina sp. 1

Conescharellina sp. 1

Figure 64 View FIGURE 64

Figured material. PMC EDM-Collection J.H.B.151a, sample 19063 ( Figure 64A–F View FIGURE 64 ) and sample 19206 ( Figure 64G View FIGURE 64 ); Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Description. Colony small, flat, discoidal, height 0.512 –0.674 mm and basal diameter 0.946 –1.072 mm in our specimens (mean H/BD 0.58), with 10– 12 slightly prominent, radial rows corresponding with the projecting peristomes of the autozooids, alternating with valleys occupied by irregular rows of interzooidal avicularia. Autozooids 2–3 per row; orifices of autozooids in the same row vertically aligned but alternating with orifices of autozooids in neighbouring rows; autozooids observed on the antapical surface distinct, separated by sloping vertical walls, with 2–3 circular to slit-like, regularly spaced marginal pores (9–20 µm in diameter) on each side, elliptical to oval, elongate (mean ZL/ZW 1.63); interzooidal communication through small, circular, uniporous pore-chamber windows, 3–4 along each lateral margin of the zooids, 8–18 µm in diameter. Frontal shield convex around the orifice, flat centrally, smooth, nodular, imperforate except for one or two elliptical marginal areolar pores (15– 16 µm in maximum diameter) placed laterally. Primary orifice with semielliptical anter and rounded triangular condyles, 6–8 µm long, pointing mediodistally and defining a shallow U-shaped sinus, longer than wide (mean OL/OW 1.30), often concealed by the peristome; apical pore absent; peristome tubular, well developed all around the orifice, 25–50 µm long. Interzooidal avicularia circular arranged in radial, sinuous or linear rows between autozooids, with up to four avicularia per row, rostrum slightly raised, randomly directed, either distolaterally or proximolaterally, crossbar complete. Apical surface coarsely tubercular, occupied by kenozooids with circular openings (42–80 µm in diameter) and sparse avicularia; antapical surface with kenozooidal pits and avicularia, like those on the frontal, centrally.

Measurements (µm). ZL (measured on the antapical surface) 425±28, 398–475 (1, 6); ZW (measured on the antapical surface) 261±36, 216–303 (1, 6); OL 100 (1, 1); OW 77 (1, 1); AvL (frontal) 41±8, 19–52 (2, 18); AvW (frontal) 41±6, 33–52 (2, 18); AvL (base) 39±4, 36–42 (1, 2); AvW (base) 39±1, 38–40 (1, 2).

Remarks. Although Conescharellina brevirostris found in the same samples appears very similar to this species, there are some differences. Conescharellina sp. 1 has flatter more discoidal colonies than the subconical colonies of C. brevirostris . It also has fewer autozooids per row, more irregularly placed interzooidal avicularia, no avicularia distolateral to the orifice, and no associated apical pore. Additionally, the autozooids are slightly smaller, while the avicularia are similar in size. The orifice shape is very similar, but the peristome is less developed distally in C. brevirostris . We have left this species in open nomenclature due to the absence of ovicells. We also believe that all the observed differences could be due to the age of the colony. It is possible that this flatter form with smaller and fewer autozooids, the lack of avicularia associated with the orifice, and the absence of ovicells (although these are rare also in C. brevirostris ) could indicate a young stage of the same species. We have kept it separated in anticipation of discovering additional specimens in the future that may provide further information.