Fridericia sp.

Chen, Juanjuan, Schmelz, Rüdiger M., Zhang, Zuxu & Xie, Zhicai, 2022, The enchytraeid fauna (Enchytraeidae: Clitellata) of the Fanjing Mountain National Nature Reserve (China) with description of two new species, Journal of Natural History 56, pp. 1957-1996 : 1982-1985

Fridericia sp.

( Figures 15 , 16 )

Material investigated

GZO202010002, stained and whole-mounted, one mature specimen from site 1, GZO202010003, stained and whole-mounted, one mature specimen from site 7. CJJ 101, CJJ 122, two mature specimens from site 1, whole worm used for DNA extraction, preserved as total DNA.

Further material investigated

Five mature specimens from site 1, one mature specimen from site 7, one mature specimen from site 12, seven specimens in total, preserved in 75% ethanol.

Description

Small worms. Length 6–7 mm. Diameter 0.2–0.25 mm at VII, 0.24–0.3 mm at XII. Number of segments 39–46. Chaetae straight, without pronounced ental hook (a small bend is present), formula 2–4 – 2, 3: 3, 4 – 2–4. A maximum of 4 per bundle, mostly 4 in ventral preclitellar bundles, inner pair slightly thinner and shorter than outer pair, mostly 2 in posterior body half. Epidermal gland cells elongate, scattered in 3–4 rows per preclitellar segment, 4–5 cells in first row, followed by a second row with more cells. Body wall ca. 15 μm in thickness (in vivo). Clitellum girdle-shaped, cells arrangement almost reticulate, hyalocytes distinctly larger than granulocytes. Brain ovoid, anteriorly convex, posteriorly rounded. A pair of short, unbranched oesophageal appendages free in ventral part of IV–V ( Figure 15a ). Pharyngeal glands with dorsal connection present in IV, absent in V and VI. Ventral lobes absent in IV, largest in VI ( Figures 15a , 16a ). Four pairs of preclitellar nephridia, from 6/7–9/10, anteseptale ca. half as long as postseptale, medial origin of efferent duct. Coelomocytes. Mucocytes with refractile vesicles at the cell periphery, lenticytes milletshaped, scarce. Dorsal vesicle from XVIII, blood colourless. Chylus cells in XIII–XIV, occupying 2 segments ( Figure 16d ). Seminal vesicle absent. Sperm funnel cylindrical, tapering proximad, collar distinct, somewhat narrower than funnel body, ca. 143 μm long, 41 μm (at collar) and 53 μm (at funnel body) wide (in vivo) ( Figures 15d, e , 16e, f ). Spermatozoa ca. 150 μm (in vivo). Male copulatory organ medium-size, bursal slit staple-shaped. Subneural glands absent. Spermathecae without ectal gland; ectal ducts elongate (ca. 230 μm, in vivo), slightly projected into ampullae;ampullae without diverticula,onion-like, lumen large, containing sperm; proximal part elongate, forming ental ducts, adjacent or joint opening of the spermathecae into oesophagus dorsally ( Figures 15b, c , 16b, c ).

Remarks

The investigated specimens agree in almost all characters with Fridericia bretscheri Southern, 1907 , especially when considering the redescriptions by Rota (1995) and Schmelz (2003). However, the absence of spermathecal ectal glands disagrees with the diagnosis of Fridericia bretscheri , where the gland is conspicuously large, its size being one of the key characters of the species. Furthermore, in our specimens postclitellar segments have predominantly 2 chaetae per bundle, while in F. bretscheri there are 4 or 3. The colour of epidermal gland cells and pattern of midventral clitellar gland cells are unknown in our specimens. Before erecting this species as new and different from F. bretscheri , we prefer to wait for more specimens from the Mt. Fanjing site to complete the description and for DNA sequences from European populations of F. bretscheri .

Figures

Figure 15. Fridericia sp. a) Segment 3 to segment 6, dorsal view. b) Spermatheca. c) Spermathecae. d) Sperm funnel. e) Sperm funnel. Scale bars: 50 µm. Abbreviations: oa, oesphageal appendage; st, spermatheca.

Figure 16. Micrographs of Fridericia sp. a, d fixed; b, c, e, f in vivo. Scale bars: 50 µm. a) Pharyngeal glands. b) Spermathecae. c) Spermatheca. d) Chylus cells. e, f) Sperm funnel. Abbreviations: dl, dorsal lobes; vl, ventral lobes.