Adeona odontoti, Martha & Scholz, 2025

Adeona odontoti sp. nov.

urn:lsid:zoobank.org:act:

( Fig. 7.1–4 View FIGURE 7 )

Material examined. Holotype: SMF 40782 About SMF (St. 283 KU; Fig. 7.1–4 View FIGURE 7 ).

Etymology. Derived from Modern Greek οδοντωτή (‘dentate’), referring to the denticles associated with the spiramen.

Description. Colonies rigidly erect, multiserial, bilamellar, dichotomously branching ( Fig. 7.1 View FIGURE 7 ). Autozooids arranged quincuncially, separated by thin, calcified threads. Pore chambers, ancestrula and early astogeny not observed.

Autozooids subhexagonal, 358–491 μm (ẋ = 408 ± 39 µm; CV = 9; N = 20 on 1 specimen) long by 182–272 μm (ẋ = 223 ± 19 µm; CV = 9; N = 20 on 1 specimen) wide ( Fig. 7.2 View FIGURE 7 ). Frontal shield moderately convex, granular, pierced by one row of evenly spaced, circular areolar pores at the margins. Orifice semicircular with well-rounded proximolateral margins, 66–94 μm (ẋ = 80 ± 8 µm; CV = 10; N = 20 on 1 specimen) long by 86–129 μm (ẋ = 103 ± 11 µm; CV = 11; N = 20 on 1 specimen) wide ( Fig. 7.3 View FIGURE 7 ). Spiramina non-projecting, single; outer opening located medially, inside depression, transversely elliptical, bearing three denticles at distal and proximolateral margins, 27–63 μm (ẋ = 39 ± 10 µm; CV = 25; N = 20 on 1 specimen) long by 33–60 μm (ẋ = 42 ± 7 µm; CV = 17; N = 20 on 1 specimen) wide ( Fig. 7.3 View FIGURE 7 ); frontal shield sloping into spiraminal depression from all sides. Spine bases lacking. Ovicells not observed .

Avicularia monomorphic, adventitious, suboral, triangular, bilaterally symmetrical, 79–127 μm (ẋ = 100 ± 10 µm; CV = 10; N = 20 on 1 specimen) long by 58–75 μm (ẋ = 65 ± 5 µm; CV = 7; N = 20 on 1 specimen) wide ( Fig. 7.4 View FIGURE 7 ). Avicularian aperture central, transversely elliptical; crossbar absent. Rostrum acutely triangular, directed laterally or slightly proximolaterally or distolaterally .

Kenozooids not observed.

Remarks. Amui (2005) described three adeonid species of the genus Adeonella Busk, 1884 , from the Bab-el-Mandeb Strait and the Gulf of Aden. All three species possess a porous frontal shield, whereas Adeona odontoti sp. nov. is distinguished by having a single row of evenly spaced, circular areolar pores along the margin of the frontal shield ( Fig. 7.2 View FIGURE 7 ). Additionally, the new species features a monoporous, denticulate spiramen ( Fig. 7.3 View FIGURE 7 ), structures not observed in the previously described Adeonella species from the region. Adeona odontoti sp. nov. is the first species from the western Indian Ocean assignable to the genus Adeona .

The closest known relatives of Adeona odontoti sp. nov. appear to be Adeona arculifera Canu & Bassler, 1929 and Adeona articulata Canu & Bassler, 1929 , both originally described from the southern Sulu Sea. In Adeona arculifera , avicularia are distolaterally oriented and indent the orifice. Colonies of Adeona articulata are articulated but also exhibit skeletal branching; their avicularia are large, distolaterally directed, and may possess a trifoliate aperture ( Di Martino et al. 2019). In contrast, avicularia in Adeona odontoti sp. nov. are oriented laterally, sometimes curving slightly upward or downward, and have an elliptical aperture ( Fig. 7.4 View FIGURE 7 ).