Marionina reicharti Felföldi, Nagy & Dózsa-Farkas, 2024, sp. nov.
Creators: name: Felföldi, Tamás
name: Nagy, Hajnalka
name: Dózsa-Farkas, Klára
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Clitellata
Enchytraeida
Enchytraeidae
Marionina
Marionina reicharti

description: Marionina reicharti sp. nov.
Figs 3, 4
Marionina spicula (Leuckart, 1847). Dózsa-Farkas 1995, 125–126, 128, 130.
Type material.
Holotype: Ma. 7, slide No. 3128. Type locality: (Loc. 4) Hungary, Lake Balaton, Bélatelep, Strand Bátori, lake shore, wet sand between the roots of willow trees, 46 ° 43 ' 51.5 " N, 17 ° 31 ' 41.7 " E, Leg. György Reichart, 14 Feb 2021.
Paratypes: In total, 22 (20 adult and 2 subadult) specimens: P.148.1 slide No. 3116 (three specimens), P.148.2 slide No. 3117 (three specimens), P.148.3 slide No. 3122 (two specimens), P.148.4 slide No. 3123 (four specimens), P.148.5 slide No. 3124 (two specimens), P.148.6 slide No. 3126 (two specimens), P.148.7 slide No. 3127, P.148.8 slide No. 3129 (two specimens), and P.148.9 slide No. 3130 (three specimens). Same data as for holotype.
Further material examined.
19 specimens (10 investigated only in vivo) + three specimens for DNA analysis.
Diagnosis.
(1) Small size (body length 2–3.3 mm, 137–190 µm wide at clitellum, in vivo), segment number 19–29; (2) maximum five chaetae per bundle, chaetae straight with ental hook and mostly not equal in size; (3) clitellum saddle-shaped; (4) first and second pairs of pharyngeal glands compact and united dorsally without ventral lobes; the third pair free and elongated; (5) transition between oesophagus and intestine gradual, midgut pars tumida in XVIII – XXII, extending over 3–4 segment lengths; (6) dorsal vessel origin in XII, blood colorless, the dorsal anterior blood vessel bifurcation anteriorly behind the pharynx; (7) three pairs of preclitellar nephridia; (8) coelomocytes nucleated oval or lemon-shaped with fine granules, 15–24 μm long in vivo; (9) seminal vesicle absent; sperm morulae occur in all segments; (10) sperm funnel 1.5–3 times longer than wide in vivo, collar high and narrower than funnel body; spermatozoa 46–70 µm long, heads 20–30 µm in vivo; (11) male copulatory organ oval or bean-shaped and compact, 33–47 µm long in vivo; (12) ectal duct of spermatheca surrounded by glands, wider proximally; one larger sessile gland at orifice; ampulla globular, diameter 29–40 µm in vivo with some sperm-threads or sperm bundle in it; ampulla attached to oesophagus.
Description.
Small species (Fig. 3 A), holotype 2.5 mm long, 115 µm wide at VIII and 138 µm at clitellum (fixed), segment number 28. Body length 2.0– 3.3 mm, width 130–160 µm at VIII and 137–190 µm at clitellum in vivo, length of fixed specimens 1.5–2.5 mm, width 90–135 µm at VIII and 115–160 µm at clitellum, segment number 19–29. Chaetae straight with ental hook (Fig. 3 D, E). Chaetal formula: 2.3, (4) - 2.3: (3) 4.5, (6) - 2.3, (4). The chaetae are not exactly equal in size within the bundles; often the middle chaetae slightly smaller than the ental ones, e. g., in the ventral preclitellar bundles, 20–19.5 – 18 – 20 µm or 25–22 – 20.4 – 24.2 µm long and 1.6–1.9 µm wide. The ventral chaetae slightly longer than lateral ones. At the posterior end of the body, chaetae are 21–27 μm long. Clitellum saddle-shaped in XII- 1 / 2 XIII, gland cells squarish, arranged in about 15–18 transverse rows (Fig. 3 C), midventrally absent. Head pore not seen, no dorsal pores. Epidermal gland cells inconspicuous in vivo. Thickness of body wall about 10–13 µm; cuticle thin (<1 µm).
Brain (Fig. 3 B) ca. 47–51 μm long (fixed), slightly longer than wide, incised posteriorly. Prostomial glanglia absent. In the ventral nerve cord, perikarya continuous. First and second pair of pharyngeal glands compact and united dorsally without ventral lobes; the third pair free and elongate (Figs 3 F, 4 G). Chloragocytes from IV forming a denser layer from VI, about 8–12 μm long in vivo, filled with refractive globules (Fig. 3 G). Transition between oesophagus and intestine gradual; oesophageal appendage and intestinal diverticula absent. Midgut pars tumida in XVIII – XXII, extending over 3–4 segment lengths (Fig. 3 J). Dorsal vessel from XII, blood colorless. The dorsal anterior blood vessel bifurcation in III. All coelomocytes nucleated oval or lemon-shaped with fine granules, 15–24 μm long in vivo (Fig. 3 I) and 8–10 μm, fixed. Three pairs of preclitellar nephridia in 6 / 7–8 / 9, preseptal part consisting of funnel and coils of canal, postseptal part elongate, about 1.7–3 times longer than the preseptal part, efferent duct terminal (Fig. 3 H). Seminal vesicle absent, sperm morulae and sperm bundles may occur in all segments (Fig. 4 A). Sperm funnels cylindrical, 60–95 μm long in vivo, 40–70 μm, fixed, and about 1.5–3 times longer than wide in vivo (1.2–2 times, when fixed), collar high, and narrower than funnel body (Fig. 4 D – F). Spermatozoa 46–70 µm long, heads 20–30 µm in vivo, 30–50 µm long, heads 10–22 µm, when fixed. Sperm ducts short, about 2.5–3.5 times longer than the funnel, coiled into a loose spiral, diameter 7–9 µm, in vivo. Male copulatory organ oval or mostly bean-shaped and compact (Fig. 4 B, C, F), 33–47 µm long, 18–26 µm wide, and 18–26 μm high, in vivo (30–40 µm long, 21–28 µm wide, and 18–25 µm high, when fixed). Subneural glands absent. Ectal duct of spermatheca, 26–38 µm long, surrounded along the length by glands, 14–18 µm wide proximally and 10–14 µm wide distally in vivo (20–23 µm long, 14–20 µm wide proximally, and 12–16 µm wide distally, when fixed). One larger, 15–22 µm long, sessile gland at orifice in vivo (15–20 µm, fixed) (Fig. 4 G – J). Ampulla globular, diameter 29–40 µm in vivo (25–40 µm, fixed), lumen with some sperm-threads (Fig. 4 H) or 1–3 sperm bundles (Fig. 4 I). Ampulla attached with a short ental duct to the oesophagus. One or two mature eggs at a time (Fig. 4 C, F).
Etymology.
The new species is named in the honor of György Reichart, who collected the sample with this species.
Distribution and habitat.
Known from the lake shore of Lake Balaton at Bélatelep, Strand Bátori, Hungary, in wet sand between the roots of willow trees (Loc. 4). Earlier, they were identified as Marionina spicula (Leuckart, 1847) at four stations of the Lake Balaton (between Fűzfő and Alsóörs, Balatonberény, and Bélatelep) in a fauna investigation in 1990–1992 (Dózsa-Farkas 1995). Unfortunately, these specimens were lost.
Remarks on the studied specimens.
Some small enchytraeid worms during the former study of Lake Balaton shore fauna were identified as Marionina spicula (Dózsa-Farkas 1995); therefore, the question was raised if they really belonged to this species known typically from marine habitats. However, in two papers (Lafont and Juget 1976; Rodriquez 1986), the species was observed along rivers without a detailed morphological description, and its euryhalinity was also reported previously (Giere 1971). This initiated our study with a freshly collected sample from the shore of Lake Balaton, combining DNA sequencing with morphological investigation. Since some specimens fitting the description of M. spicula (Nielsen and Christensen 1959) were detected in the Adriatic shore samples (collected in 2019), those specimens were also included in our comparison. Furthermore, specimens collected from a Danish seashore in 1999 (site 5) were also studied, but unfortunately, we were not able to obtain DNA sequences from them due to their fixation in Bouin’s fluid. The results of the molecular analysis revealed that the DNA sequences of the Hungarian specimens (Lake Balaton) differ from those of the individuals collected by us from the Adriatic seashore (site 1, Table 1) and from the single DNA sequence of M. spicula in NCBI GenBank (see details below), so there is support at the DNA level that the Balaton specimens belong to a new species.
Differential diagnosis.
Our species comparison is based on Nielsen and Christensen (1959), and it includes observations on living individuals collected in Denmark on the Nivå coast in 1999 (site 5) and reinvestigated (as fixed material) in this study. The morphological differences are as follows: M. reicharti sp. nov. is smaller (2–3.3 mm length vs. 4–5 mm length in M. spicula in Denmark, in vivo, 1.5–2.5 mm length vs. 2.1–2.6 mm length, fixed), segment number 19–29 vs. 27–30. Sperm funnel slightly shorter (40–70 µm long vs. 67–90 µm, fixed), the spermatozoa are longer in the new species (30–50 µm, heads 11–22 µm vs. 20–38 µm, heads 10–17 µm in M. spicula). The ectal duct of the spermatheca is longer in Danish M. spicula specimens and proximally wider (20–50 µm long and 16–50 µm wide vs. 20–23 µm long and 14–20 µm wide in the new species). Origin of the dorsal vessel from segment XII vs. from XIII in Danish M. spicula specimens.
Keeping in mind that the Mediterranean M. spicula specimens studied here may belong to a different species, and since the origin of M. spicula specimen CE 2561 is from Sweden (see additional details below), we performed a morphological comparison of Mediterranean M. spicula with the new species: M. reicharti sp. nov. is smaller and has in general fewer segments: length 3 mm, width 137–190 μm at clitellum in vivo, 19–29 segments (vs. 3–7 mm, 200–430 μm, 21–39 segments, respectively). The maximum number of ventral chaetae is lower, 5–6 (vs. 7–8). The clitellum is saddle shaped (vs. ring-shaped, glands absent only between the male openings). The spermatozoa are 46–70 µm long, heads 20–30 µm in vivo (vs. 60–120 µm long and 30–43 µm), the male copulatory organ is also smaller, 33–47 µm long, 18–26 µm wide, 18–26 µm high (vs. 45–70 × 45–60 × 35–50 µm). Furthermore, the size of the spermatheca is different: ectal duct 26–38 long, ectal gland 15–22 µm long, diameter of ampulla 29–40 µm in vivo (vs. 35–51 µm, 30–40 µm and 40–63 µm, respectively). The coelomocytes and the size of sperm funnels are not comparable, because these traits in the specimens of M. spicula collected at the Adriatic seashore are very variable (a sign of that possibly M. spicula is a species complex).
Morphological notes on the Marionina spicula (Leuckart, 1847) specimens of the Adriatic seashore
Figs 5 – 6
Material examined. About 50 specimens were investigated in vivo, slides were made from 28 specimens, and 11 specimens were used for DNA analysis. Collecting site: (Loc. 1) Croatia, Istria, Kale Cove seashore, Adriatic Sea, Kamenjak Peninsula, decaying seagrass (Zostera) detritus, 44 ° 51 ' 13.0 " N, 13 ° 58 ' 50.5 " E, Leg. Júlia Török, 03 Apr 2019, and 05 Sep 2020.
Description of new material. Small worms, body length 3–7 mm, width 200–430 µm at clitellum in vivo; length of fixed specimens 1.9–3.6 mm, width 170–320 μm at clitellum, segment number 21–39. Chaetae straight with ental hook. Chaetal formula variable: 2-5 - 4-2: 4-8 - 6-2. The chaetae unequal in size within the bundles. Mostly the chaetae towards the midlines of the body are shorter than the lateral ones, or the chaetae in the middle of the bundles are shorter (Fig. 5 A – C). Clitellum ring-shaped in XII- 1 / 2 XIII, gland cells arranged in irregular transverse rows (Fig. 5 E), between the male openings absent (Fig. 5 F). Head pore at the middle of prostomium, no dorsal pores. Epidermal gland cells inconspicuous in vivo.
Brain (Fig. 5 D) 62–87 μm long (fixed), 1.5 times longer than wide, incised posteriorly. Pharynx and postpharyngeal bulbs well developed. Prostomial ganglia absent. In the ventral nerve cord, perikarya continuous. First and secondary pharyngeal glands compact and united dorsally; the third pair free (Figs 5 G, 6 F). Chloragocytes from IV forming a denser layer from VI, about 15–20 μm long in vivo, filled with refractive globules. Transition between oesophagus and intestine gradual; oesophageal appendages and intestinal diverticula absent. Midgut pars tumida not seen. Dorsal vessel from XII, blood colorless. The dorsal anterior blood vessel bifurcation in III, pharyngeal (Fig. 5 G). Coelomocytes variable (Fig. 5 H – K), nucleated, disc-shaped with gray granules; in some specimens, the coelomocytes are with few granules (Fig. 5 J), so they are pale in the coelom. In other specimens, the coelomocytes are filled with granules (Fig. 5 K), and the coelomocytes are in such large numbers that they fill the entire coelom and are dark gray in transmitted light (Fig. 5 I), 15–24 μm long in vivo, and 15–17 μm, fixed. Three pairs of preclitellar nephridia in 6 / 7–8 / 9, preseptal part consisting of funnel and coils of canal, postseptal part elongate, about 2–2.5 times longer than the preseptal part, efferent duct terminal (Fig. 6 A). Seminal vesicle absent. Sperm funnels cylindrical, very variable; they can be about 110–150 μm long and 1.7–2.4 times longer than wide (Fig. 6 B, C); in other specimens, they are very large, 170–300 μm long and 3–4.5 times longer than wide in vivo (Fig. 6 D, E), collar 10–25 μm high and narrower than funnel body. Spermatozoa 60–120 µm long, heads 30–43 µm in vivo. Sperm ducts short, about three times longer than the funnel, diameter 10–13 µm, in vivo (Fig. 6 C). Male copulatory organs compact (Fig. 5 F), 45–70 µm long, 45–60 µm wide, and 35–50 μm high in vivo (32–58 µm long, 30–53 µm wide, and 28–40 µm high, when fixed). Ectal duct of spermatheca 35–51 µm long, surrounded along the length by glands and one larger, 30–40 µm long, sessile gland at orifice. Ampulla rounded (diameter 40–63 µm wide in vivo, 35–53 µm, fixed), sometimes with a rather thick wall (6–14 µm) in the lumen with sperm (Fig. 6 F, G). Ampulla attached with a short ental duct to the oesophagus. One or occasionally two mature eggs at a time (Fig. 6 C). In this species, as already pointed out by Giere (1971), it is often observed that the coelomic fluid, released through the anus, attaches itself to the grains of sand (Fig. 6 H).
description: Published as part of Felföldi, Tamás, Nagy, Hajnalka & Dózsa-Farkas, Klára, 2024, New data on the polyphyletic Marionina genus (Annelida, Enchytraeidae): description of three new species from European shore habitats, pp. 1269-1286 in Zoosystematics and Evolution 100 (4) on pages 1269-1286, DOI: 10.3897/zse.100.122874