Canda lunata, Martino & Rosso & Taylor & Chiu & Fujita & Kitamura & Yasuhara, 2025

Canda lunata sp. nov.

Di Martino, Rosso and Taylor

Figure 12 View FIGURE 12

zoobank.org/ 56822F86-59BA-45FC-B8D1-791A06758EA7

Type material. Holotype PMC. B47. 29.7.2024 a, sample 19029 ( Figure 12A–E View FIGURE 12 ); paratype PMC. B47. 29.7.2024 b, sample 19227 ( Figure 12F–G View FIGURE 12 ); Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Etymology. Latin, meaning crescent-shaped, referring to the shape of the ectooecial fenestra.

Diagnosis. Canda with biserial branches becoming triserial at bifurcations, triangular in cross-section; autozoids club-shaped, arranged in alternating series; gymnocyst absent; proximal cryptocyst extensive smooth and pitted; opesia transversely elliptical with two distolateral spines, one on each side; scutum lacking; small drop-shaped avicularia of two types: adventitious distolateral and frontal interzooidal, both on a columnar cystid; ovicells covering the proximal margin of the opesia of the distal zooid, ooecium smooth with crescent-shaped ectooecial fenestra; vibracula on the dorsal side with an obliquely placed setal groove only slightly curved.

Description. Colony erect with narrow (245–395 µm) branches; branches rectilinear, biserial transitioning to triserial at bifurcations, triangular in cross-section; articulating nodes not observed. Autozooids distinct, separated by shallow grooves and a slightly raised rim, club-shaped, elongate (mean ZL/ZW 1.93), arranged alternately in two longitudinal, series. Gymnocyst absent; cryptocyst smooth, pitted, slightly depressed, extensive proximally, occupying two-fifths of the frontal surface (mean CryL/ZL 0.36), tapering laterally, absent distally. Opesia elliptical, nearly parallel-sided, occupying two-thirds of the frontal surface (mean OpL/ ZL 0.65); a single spine on each distolateral corner, 10–18 µm in diameter at the base, concealed in ovicellate zooids; scutum lacking; two oval communication pores and muscle scars visible through the opesia. Avicularia small, drop-shaped, occurring in two types: adventitious, placed distolaterally adjacent to the opesia externally, atop a conical cystid, slightly sloping outwards and directed laterally; frontal interzooidal, positioned on a columnar cystid directed proximo- or distolaterally; cystids 60– 90 µm in length; crossbar lacking. Ovicells globular, placed on the cryptocyst of the distal zooid, partially covering its proximal margin and more of the inner corner; ooecium smooth with an ectooecium featuring a transversely placed, crescent-shaped fenestra, 55–75 µm long by 100–120 µm wide, exposing the endooecium. Dorsal side occupied by vibracula with a long, obliquely placed, only slightly curved, deep setal groove; a shallow sinuous median furrow corresponding to zooidal boundaries; on each vibraculum a large, circular radicular pore measuring 17–23 µm in diameter, located proximally on the outer side.

Measurements (µm). ZL 359±9, 353–369 (1, 3); ZW 186±6, 182–193 (1, 3); OpL 234±28, 209–264 (1, 3); OpW 123±29, 104–156 (1, 3); CryL (proximal) 131±12, 113–150 (2, 8); AvL (adventitious) 36±2, 34–39 (2, 5); AvW (adventitious) 18±4, 14– 24 (2, 5); AvL (interzooidal) 33±2, 31–36 (2, 6); AvW (interzooidal) 23±4, 19–28 (2, 6); OvL 154±11, 139–164 (1, 4); OvW 185±7, 177–192 (1, 4); VibrL 179±14, 163–198 (2, 9); VibrW 115±11, 94–134 (2, 9).

Remarks. The absence of a scutum in this subfossil species is not due to preservational issues as there are no basal structures from which it might have detached. Among the Recent and fossil Indo-Pacific species of Canda lacking a scutum, C. giorgioi Di Martino and Taylor, 2014 , and C. federicae Di Martino and Taylor, 2014 , from the Miocene of East Kalimantan ( Indonesia), differ in their lack of avicularia and a more curved setal groove of the vibracula. However, C. federicae is the most similar in the overall appearance of the autozooids. Canda pecten differs in having a triangular asymmetrical opesia, while C. clypeata (Haswell, 1880) has large frontal avicularia with a curved rostrum directed towards the centre of the branch ( Tilbrook, 2006).

In the original description of the Indonesian species reported by Di Martino and Taylor (2014, pp. 57, 58), the authors did not designate a holotype specimen. Following the re-examination of this material for this work, we designate specimen NHMUK PI BZ 6882 as the lectotype (NHMUK PI BZ 6883 as the paralectotype) for C. giorgioi , and specimen NHMUK PI BZ 6884 as the lectotype (NHMUK PI BZ 6885 as the paralectotype) for C. federicae .