Fridericia ventrochaetosa, Nagy & Felföldi & Dózsa-Farkas, 2018

Nagy, Hajnalka, Felföldi, Tamás & Dózsa-Farkas, Klára, 2018, Morphological and molecular distinction of two Fridericia species (Clitellata, Enchytraeidae) having same spermatheca type, Zootaxa 4496 (1), pp. 111-123 : 112-117

publication ID	https://doi.org/ 10.11646/zootaxa.4496.1.8
publication LSID	lsid:zoobank.org:pub:AEBC3EB5-DD2A-49BB-898F-EA792AEBBC46
DOI	https://doi.org/10.5281/zenodo.5951820
persistent identifier	https://treatment.plazi.org/id/5B1D2668-FFA7-950E-C3F9-F9C2FCBFFC7B
treatment provided by	Plazi
scientific name	Fridericia ventrochaetosa
status	sp. nov.

Treatment

Fridericia ventrochaetosa sp. n.

( Figures 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Fridericia sp. Dózsa-Farkas & Felföldi 2017: 52 – 53, 2018: 4 – 5.

Holotype. F. 29, slide No. 2267, adult, unstained, whole-mounted specimen.

Type locality. Kȏszeg Mts. ( Hungary), Steirer Houses, mesophile montane hay meadow, 47o22.201N, 16o28.045E, 667 m asl, leg. K. Dózsa-Farkas, J. Farkas, M. Pobozsny, 24.10.2016. GoogleMaps

Paratypes (in total 14 specimens). P.112.1.1–112.1.4, slides No. 2218, 2219 (DNS 978), 2225, 2226, four adult, stained specimens from Rax Mts., mixed forest ( Picea abies , Betula pendula ), 47o40.538N, 15o43.140E, 1116 m asl, leg. J. Farkas, 13.05.2016. P.112.2.1–112.2.7, slides No. 2266a–c– 2268–2269 (DNS 1102), 2273– 2274, 2345 (DNS 1116), 2346, 7 adult specimens, stained (except P.112.2.4 No. 2273), whole-mounted specimens

from the type locality, leg. K. Dózsa-Farkas, J. Farkas, M. Pobozsny, 24.10.2016. P.112.3, one specimen in 70% ethanol (body end was processed for molecular analysis, DNS 1114).

Further material examined. Four juvenile and two adult specimens in vivo (the whole adult specimens were processed for molecular analysis, DNA 1009, 1115).

Etymology. Named after the chaetae, which are present only in the ventro-lateral chaetal bundles.

Diagnosis. The new species can be recognized by the following combination of characters: (1) large size (body length 15–24 mm in vivo), segments (43) 48–60; (2) lateral chaetae absent, ventral maximum 3–4 chaetae per bundle; (3) clitellum widely interrupted dorsally and the hyalocytes and granulocytes arranged in dense rows laterally and after the bursal opening; (4) body wall strong and cuticle thick (8–14 µm); (5) five preclitellar pairs of nephridia; (6) coelomo-mucocytes b-type, lenticytes large, 8–12 µm long; (7) blood light pink; (8) chylus cells in XII–XV, occupying 2–3 segments; (9) bursal slit longitudinal with transverse extensions; (10) seminal vesicle large; (11) subneural glands absent; (12) sperm funnel approximately as long as body diameter or somewhat longer, collar narrower than funnel diameter, spermatozoa long, difficult to measure, sperm heads 150–250 µm long (in vivo); (13) spermatheca with 4–6 stalked diverticula, long ectal duct without ectal glands and separate entally.

Description. Large, whitish, stiff worms. Holotype 23.3 mm long, 530 µm wide at VIII and 630 µm at the clitellum (in vivo). The fixed worm 19.0 mm long, 700 µm wide at VIII and 750 µm at the clitellum, 56 segments. Body length of the paratypes 15–24 mm, width 500–620 µm at VIII and 600–730 µm at the clitellum (in vivo). Length of fixed specimens 11.5–18.5 mm, width 520–700 µm at VIII and 600–770 µm at the clitellum. Segments (42), 48–60. Chaetae only in ventro-lateral bundles, except in one specimen (P. 112.2.5. slide No. 2273), here 1 chaeta in 1 lateral bundle of IV. Chaetal formula: 0 – 0: 1,2,3,(4) – (3),2,1,0,1. Inner chaetae shorter and thinner than outer: 58– 70 x 5–6 µm against 70– 80 x 9 µm and 34– 42 x 4 µm (in preclitellar bundles). Behind clitellum the two chaetae in a bundle of different size, at body end often only 1 chaeta per bundle, size about 90–110 x 10–12 µm. Head pore at 0/I. Dorsal pores from VII. Epidermal gland cells 5–6 transverse rows per segments ( Fig. 1C View FIGURE 1 ). Epidermis glandular around spermathecal pore ( Fig. 3G View FIGURE 3 ). Clitellum in XII–1 /2XIII. Glands dorsally absent, gap about 200–400 µm wide ( Fig. 1I View FIGURE 1 ), ventrally absent between and anterior to male apparatus, but present posteriorly ( Fig. 2B View FIGURE 2 ), hyalocytes larger than granulocytes, arranged in dense transverse rows ( Fig. 1H View FIGURE 1 ). Body wall strong, thickness about 40–70 µm, cuticle thick, about 8–14 µm in vivo and fixed ( Fig. 1D View FIGURE 1 ), (in forepart slightly stronger than at the body end). Brain egg-shaped, about 200–240 µm long, about two times longer than wide in vivo ( Fig. 1A View FIGURE 1 ) and 170–203 µm long and 1.4–1.8 times longer than wide in the fixed specimens ( Fig. 1B View FIGURE 1 ). Oesophageal appendages long with numerous, elongate branches at the end in V–VI ( Fig. 2A View FIGURE 2 ). All pharyngeal glands with ventral lobes, those in 4/5 mostly united dorsally, those in 5/6 and 6/7 weakly united dorsally, occasionally all three pairs unconnected dorsally. Septa of V–X thickened ( Fig. 1E View FIGURE 1 ). Chloragocytes from V, 15–25 µm long (fixed specimens). Dorsal vessel from XX–XXIII, blood light pink. Midgut pars tumida in XXX–XXXVIII occupying 5– 7 segments ( Fig. 2C View FIGURE 2 ). Five pairs of preclitellar nephridia from 6/7 to 10/11, length ratio anteseptale: postseptale 1: 1.5–2, adseptal origin of the long efferent duct. The nephrostome not embedded in the anterior part, oriented horizontally (infrequent in Fridericia species) ( Figs. 1L–M View FIGURE 1 ). Coelomo-mucocytes b-type, i.e. with refractile vesicles at cell periphery, length 34–53 µm in vivo ( Fig. 1J View FIGURE 1 ), 20–35 µm in the fixed worms ( Fig. 1K View FIGURE 1 ). Lenticytes scarce, large, 8–12 µm long. Chylus cells in XII–XV, occupying 2–3 segments ( Fig. 2D View FIGURE 2 ). Seminal vesicle in IX–X or XI–XII. Sperm funnels cylindrical, mostly tapering distad ( Fig. 2I View FIGURE 2 ), about 600–860 µm long and 2.4–3 times longer than wide (in one specimen 4 times longer than wide) (in vivo). Funnel length in fixed specimens 350–550 µm, funnel 1.5–2.5 times longer than wide ( Figs. 2J View FIGURE 2 , 3A View FIGURE 3 ); collar narrower than funnel body. The entire length of spermatozoa is difficult to measure in vivo, heads 150–250 µm, in fixed specimens spermatozoa 350–700 µm long and sperm heads 150–230 µm. Diameter of sperm ducts 9–10 µm (fixed). Male copulatory organs large, 260–350 µm long, 130–160 µm wide and 110–125 µm high (fixed), bursa large ( Figs. 2B,E,H View FIGURE 2 ). Bursal slits longitudinal with additional transverse extensions ( Figs. 2F–G View FIGURE 2 ). Subneural glands absent. Spermathecae ( Figs. 3B–F View FIGURE 3 ) similar to the spermathecae of F. galba ( Figs. 5D–E View FIGURE 5 ): no ectal gland, ectal ducts very long, about 650–840 µm and 32–35 µm wide, canal about 8 µm wide in vivo (520–640 µm long, 25–30 µm wide, canal 5 µm, fixed), not widening entally, projecting into ampulla, ental bulbs wide, about 70–90 µm. Ampullae surrounded distally by 4–6 stalked diverticula of various size: diameter of diverticula 45–90 µm, stalks about as wide and long as diverticula, with ciliated subchamber, ampullae 100–130 µm wide and not considerably set off from distal part, separate openings into oesophagus. 1–3 mature egg at a time.

Distribution and habitat. In Kȏszeg Mts., in mesophile montane hay meadow, and in Rax Mts., in a mixed forest ( Picea abies , Betula pendula ).

Differential diagnosis. There are only two species of Fridericia , F. paraunisetosa Xie et al. 2000 from NE China and the new species, with multiple spermathecal diverticula plus laterally completely absent chaetae. F. paraunisetosa can easily be distinguished from F. ventrochaetosa sp. n. based on the following characters: smaller size (5.0– 7.8 mm vs. 11.5–18.5 mm, fixed), in ventral bundles only one chaeta per bundle (vs. 2–4), dorsal pores only from XVIII (vs. from VII), brain incised anteriorly (vs. concave), oesophageal appendages stout and unbranched (vs. many branches) and spermatheca with sessile diverticula (vs. with stalk) ( Xie et al. 2000).

Apart from the absence of the lateral chaetae, the new species is highly similar morphologically to Fridericia galba . To compare the two species, we studied specimens of F. galba sampled from the same two mountains where the new species occurred, and some additional specimens from other sites in Hungary. All these specimens of F. galba had spermathecae with more than 5 spermathecal diverticula. The comparison of the most important traits of the two species is given in Table 1. Table 1 shows that the two species are broadly the same in size, number of segments, oesophageal appendages, origin of dorsal vessel, sperm funnel (comp. Figs. 2I –J View FIGURE 2 , 3A View FIGURE 3 with Fig. 5C View FIGURE 5 ), the male apparatus (comp. Figs. 2E,H View FIGURE 2 with Fig. 4J View FIGURE 4 ). Spermathecae are also almost the same: ectal duct very long, no ectal gland, more than 2 diverticula with stalks (comp. Figs. 3B–F View FIGURE 3 with 5D–E). The number of diverticula is mostly the same (6), but it varies in the new species between 4 and 6 and in the individuals of F. galba studied by us, between 5–9. The shape of the diverticula and the subchamber and ampullae are almost the same, only the stalks are slightly shorter ( Table 1). However, differences can also be observed. The main differences are the absence of the lateral chaetae and the lower number of ventral chaetae in the bundles in the case of the new species (maximum of 3–4; in F. galba 4–7, Fig. 4E View FIGURE 4 ). Furthermore, both species have thick body wall but the cuticle in F. ventrochaetosa sp. n. is much thicker (8–14 µm; in F. galba 1–1.5 µm) ( Table 1, Figs. 1D View FIGURE 1 vs. Fig. 4D View FIGURE 4 ). Epidermal glands are well-visible, but in F. galba often occur conspicuous brown glands, too ( Fig. 4C, E View FIGURE 4 ). The mucocytes are about the same length and the matrix may be filled with refractile vesicles in F. galba , but this granulation in the new species is much more prominent ( Fig. 1J View FIGURE 1 ) and the lenticytes are also larger ( Table 1). Further differences: chylus cells and midgut pars tumida are further back in F. galba , and the blood is light pink in F. ventrochaetosa sp. n. but colorless in F. galba ( Table 1), and the epithelium of the prostomium of the new species is thicker, more conspicuous ( Fig. 1F–G View FIGURE 1 ), than in F. galba ( Fig. 4F View FIGURE 4 ). Last, but not least, individuals of F. galba often have large accessory sexual glands, mostly only one side in V, XI, XIII ( Figs. 4H–J View FIGURE 4 ), but these organs are absent in the new species ( Table 1). After surveying references describing F. galba previously (for complete bibliography see Schmelz 2003), it could be stated that the features of specimens studied by us fall within the range of variation reported earlier. However, since we provided more morphological characters and measurement data ( Table 1), a more detailed comparison was possible with the new species. It should be noted that in some descriptions, few traits of F. galba are more variable as in the case of our specimens; e.g. segment number 40–45, length 15–20 mm in Vejdovský (1879), (48)–64–71–(81) and 20–40 mm in Nielsen & Christensen (1959), 55–61 segments and 18– 21 mm in Rota (1994) or 60–70 segments and 15–25 mm length in Schmelz (2003), respectively. Difference could be found in the number of spermathecal diverticula; e.g. Vejdovský (1879) reported 3–5, Nielsen & Christensen (1959), Schmelz (2003), and Schmelz and Collado (2010) reported 2–8. In the case of other characters we recorded generally the same as in previous references, although most of the previous descriptions lack measured values. Other authors including us conceive that the presence of accessory sexual glands is a characteristic feature of this species, even if it is absent in some specimens. Despite the above-mentioned variation of morphological characters, the new species could be easily distinguished from F. galba .