Fabriciinae, Bick & Bastrop, 2025

Bick, Andreas & Bastrop, Ralf, 2025, Revision of the genus Manayunkia Leidy, 1859, and establishment of two subfamilies within Fabriciidae (Annelida, Sabellida), Zootaxa 5661 (1), pp. 1-58 : 7

Fabriciinae subfam. nov.

( Figure 4 )

This new subfamily is proposed for all genera of Fabriciidae , except Echinofabricia , Manayunkia and Monroika (including Brandtika (see below)).

Type genus: Fabricia Blainville, 1828 .

Diagnosis (apomorphies in italics). Small-bodied, hemisessile polychaetes with eight thoracic and three abdominal chaetigers ( Fig. 4A ). Three pairs of bipectinated radioles, i.e., radioles symetrically branched ( Fig. 4B, C ); acellular branchial skeleton present ( Fig. 4E ); radiolar lobes completely separated from one another. Ventral filamentous appendages present or absent. Branchial hearts present ( Fig. 4A ). Dorsal lips as low, narrow ridges or well-developed triangular or rounded lobes, sometimes poorly developed. Without ventral lips or lip-like processes. Anterior margin of anterior peristomial ring a low ridge dorsally and laterally; triangular, rounded or rectangular lobe ventrally with midventral ciliated patch ( Fig. 4D ). Thoracic uncini acicular, with main fang followed by smaller teeth. Abdominal uncini with elongate manubrium and dentate region; dentate region with multiple rows of equal-sized teeth. Peristomial and pygidial eyes ( Fig. 4A ). Spermiogenesis in thoracic chaetigers 3–8, 4–8 or 6–8; spermatids in large cluster with central cytophore; single, dorsal sperm duct present. Sperm nuclear projection present; sperm nuclear membrane thickening; extra-axonemal sheath present.

Remarks. With the designation of the Manayunkiinae subfam. nov. within the Fabriciidae , it is necessary to establish a subfamily for the remaining genera of Fabriciidae , Fabriciinae subfam. nov. Both subfamilies are sister taxa. In contrast to Manayunkiinae subfam. nov., Fabriciinae subfam. nov. have bipectinate radioles with an acellular supporting tissue. The feeding groove in Fabriciinae subfam. nov. is formed by 5 rows of ciliary cells, whereas in M. aestuarina it is formed by 9 to 10 rows of cells (see description of M. aestuarina , and Randel & Bick 2012; Tilic et al. 2021). Interestingly, the food groove of Sabellidae and Serpulidae is also composed of 5 ciliated cells with the same pattern of ciliation ( Evenkamp 1931; Fitzsimonis 1965; Hanson 1949; Nicol 1930; Thomas 1940). When ventral filamentous appendages appear, they can be non-vascularized or vascularized and branched or unbranched. However, it is unclear whether the ventral filamentous appendages of both taxa are actually homologous. Whereas in the Manayunkiinae subfam. nov. a ciliated band occurs ventrally at the posterior margin of the anterior peristomial ring, in the Fabriciinae subfam. nov. a ciliated spot is present here. Number of abdominal segments is constant and pygidial eyes are always present. Transitional uncini or transitional chaetae as well as a brood chamber in females are absent.

Figures

FIGURE 4. Fabriciinae subfam. nov.; A–E Fabricia stellaris (Müller, 1774) from the Baltic Sea. A. Total view of a living individual. B. Radiolar crown of a living specimen. C. SEM micrograph of radiolar crown, dorsal view. D. Anterior end, ventral view (arrow points to ciliated patch of the anterior peristomial ring lobe). E. TEM micrograph of a branch of a radiole. Scale bars. A–B 200 µm, C 100 µm, D 50 µm, E 3 µm µm (abbr: bh branchial hearts, ecm extracellular matrix, pre peristomial eyes, pye pygidial eyes, sp spermatheca).