Enchytraeus andrasiformis, Nagy & Dózsa-Farkas & Felföldi, 2023

Nagy, Hajnalka, Dózsa-Farkas, Klára & Felföldi, Tamás, 2023, New insights into the Enchytraeus albidus complex (Annelida, Enchytraeidae), with the description of three new species from seashores in Italy and Croatia, European Journal of Taxonomy 870, pp. 107-145 : 19-22

Enchytraeus andrasiformis sp. nov.

urn:lsid:zoobank.org:act:F5887255-EE25-42BD-8035-40559810DCD1

Figs 1E , 5 , Tables 1–2

Diagnosis

(1) Body length 13–19.5 mm (in vivo), segment number 30–38; (2) chaetae maximum 2–3 (4) per bundle, straight with ental hook; (3) clitellum in XII–XIII, hyalocytes and granulocytes irregularly arranged dorsally and laterally, but between the male lip-like folds ventrally absent; (4) four pairs of nephridia preclitellarly; (5) the first and second pairs of primary pharyngeal glands free dorsally with ventral lobes, third pair connected dorsally; (6) dorsal blood vessel origin from XIV, blood colourless; (7) sperm funnel variable large, 300–750 μm long, 4–7 × as long as wide in vivo; (8) vasa deferentia uniform, 18–24 μm wide with 5–7 μm thick wall (fixed), ciliated; (9) male glands multiple: one large primary bulb 80–120 μm long, 65–100 μm wide (fixed), and many smaller secondary glands. Often one additional sexual gland, rounded or oval (diameter 80–100 μm, fixed); (10) spermathecal ectal duct (62–125 μm long, fixed) covered with gland cells, ampulla spherical with one large diverticulum (90–200 μm long), ampulla connecting with oesophagus; (11) 8–14 small mature eggs present at a time.

Etymology

Named after its similarity to Enchytraeus andrasi sp. nov.

Material examined

Holotype

ITALY • Castiglione della Pescaia, Punta Ala Grosseto, decaying seagrass debris ; András and Kinga Dózsa-Farkas leg.; 24 Sep. 2020; from culture: 1 Feb. 2021; En. 4, slide 3132 ; ELTE.

Paratypes

ITALY • 1 spec., last 9 segments, 2.5 mm used for DNA analysis ( No. 1454 , ID number); same collection data as for holotype; P. 145.1, slide 3093 ; ELTE • 1 spec., same collection data as for holotype; P.145.2, slide 3094 ; ELTE .

Description

MEASUREMENTS. Medium-sized to large specimens. Holotype 13 mm long, 420 μm wide at VIII and 595 μm at clitellum in vivo (9.6 mm long, 440 μm wide at VIII and 540 μm at clitellum, when fixed), 38 segments. Body length of paratypes 14–19.4 mm, width 560–650 μm at VIII and 820–860 μm at clitellum in vivo. Length of fixed specimens 10.9–13.4 mm, width 550–610 μm at VIII and 630–720 μm at clitellum. Length of the first 12 segments 3.4–4.4 mm, after fixation. Segment number 30–34.

CHAETAE. Chaetal formula: (2),3–3,2,1:3,(4)–3,(2). Four chaetae in the ventral bundles were observable only in one case. Chaetae straight with ental hook, about equal in size within a bundle, 65–75 μm × 4–5 μm preclitellarly and 67–85 μm × 4–5 μm posteriorly. Often found 2–3 surplus chaetae near the bundles ( Fig. 5D ). Chaetae absent in XII ventrally and laterally, but in one specimen present laterally.

EPIDERMAL GLANDS. Inconspicuous.

CLITELLUM. Girdle-shaped, in XII–XIII, (but in paratype slide 3093 in ½XI–¼ XIII), hyalocytes and granulocytes irregularly arranged dorsally and laterally ( Fig. 5B–C ), absent between male lip-like folds in ventral recess ( Fig. 5H ). Before and behind this area clitellar cells present.

HEAD PORE. At 0/I.

BRAIN ( Fig. 5A ). About 1.7–2.2 × as long as wide, truncate posteriorly, sides slightly merging anteriad.

OESOPHAGEAL APPENDAGES. Pair of blind-ending tubes. First and second pair of primary pharyngeal glands free dorsally with ventral lobes ( Fig. 5E ), but the third pair connected dorsally.

DORSAL BLOOD VESSEL. From XIV, blood colourless. Anterior bifurcation near prostomium.

NEPHRIDIA. Four pairs of preclitellar nephridia from 6/ 7–9 /10, anteseptale funnel only, postseptale bulged, efferent duct short, origin postero-ventrally.

COELOMOCYTES. Oval, texture granulated, about 30–36 μm long, in vivo [20–30 μm, fixed ( Fig. 5F )], shining, hyaline corpuscles absent.

SUBNEURAL GLANDS. Absent.

SPERM SACS. Two paired large lobes of sperm sacs, filling in all coelom of X–XI. Testes and sperm funnels in XI, ovaries, male pores and glands in XII.

SPERM FUNNELS. Variably large, 300–750 μm long, 4–7 × as long as wide in vivo (220–470 μm long and 3–4 × as long as wide, fixed), collar of same width as funnel itself or slightly wider ( Fig. 5G ). Vasa deferentia uniform, irregularly coiled in XII, about 18–24 μm wide with 5–7 μm thick wall (fixed), slightly ciliated.

SPERMATOZOA. 105–130 μm long, heads about 28–48 μm, in vivo.

MALE COPULATORY ORGANS. Male glands multiple: one larger rounded primary bulb (80–120 μm long, 65–100 μm wide, fixed) and many smaller secondary glands (28–65 μm long, fixed). Secondary glands arranged roughly in semicircle around male pore and primary bulb, 215–300 μm in length, fixed. In holotype and one paratype (slide 3094), at one end of smaller glands of both male copulatory glands, one round (diameter 80–100 μm, fixed) extra sexual gland observable ( Fig. 5H–I ). In another paratype (slide 3093) these glands not observable. Male pores covered by lip-like folds (about 130 μm wide).

SPERMATHECAE ( Figs 1E , 5J–L ). With short ectal duct (62–125 μm long, fixed), covered with gland cells (60–95 μm widely in vivo and fixed equally), canal 2.5–5 μm wide. Ampulla spherical (diameter 100– 140 μm) with one large diverticulum (90–200 μm long and 40–100 μm wide, fixed), separate openings into oesophagus. More (8–14) small mature eggs present at a time.

Differential diagnosis

The new species, like E. andrasi sp. nov., differs from the other species of the E. albidus complex (see in the differential diagnosis of E. andrasi ) and very similar to E. andrasi morphologically, but can be considered as two separate species based on the results of molecular analysis. Some morphological differences also supported this distinction. Both species is about as long as E. albidus s. str. (10–13 mm vs 9.6–13.4 mm for E. andrasiformis sp. nov. and 6.7–9.3 mm long for E. andrasi sp. nov.) however the two new species are slightly thinner than the latter, width at clitellum (fixed) being 420–580 μm for E. andrasi , 540–720 μm for E. andrasiformis , 700–980 μm for our new material of E. albidus , and even up to 1080 μm for E. albidus studied by Erséus et al. (2019). The coelomocytes in E. andrasiformis are larger (30–36 μm long) but 18–25 μm in E. andrasi sp. nov. in vivo, (20–30 μm vs 15–20 μm, fixed), the sperm funnel is also larger (220–470 μm long vs 235–332 μm long, fixed) and the collar has the same width or slightly wider as the funnel body in E. andrasiformis , but narrower than funnel body in E. andrasi . The male copulatory organs of the two species are similar, but in E. andrasiformis the primary gland is slightly larger ( Table 2 ), furthermore, two extra sexual glands were observed in two out of three specimens.Finally, in E. andrasiformis , the two anterior pairs of primary pharyngeal glands not united dorsally, only the third pair, whereas both of the first and second pairs are united dorsally and the third pair either united or free in E. andrasi . Additional morphological data for some species of the Enchytraeus albidus complex is similar as in E. andrasi .

For similarities and differences of the species of Enchytraeus studied by us, see Table 2 .

Distribution and habitat

Punta Ala Grosseto, Castiglione della Pescaia, Italy, decaying seagrass debris.

Figures

Fig. 1. Schematic drawing of spermathecaeof the specimens studied.A. Enchytraeus adrianensissp. nov. B. E. krumbachi (Čejka, 1913). C–D. E. andrasi sp. nov. E. E. andrasiformis sp. nov. F. E. albidus Henle, 1837. G. E. irregularis Nielsen & Christensen, 1961.

Fig. 5. Micrograph of Enchytraeus andrasiformis sp. nov. A–C, F–G, I, K. Holotype (slide 3132, En. 4; ELTE). A–C, F–G, K. In vivo. D–E, H–J, L. Fixed, stained. A. Brain. B. Clitellar glands, dorsal view. C. Clitellar glands, lateral view (three eggs visible). D. Paratype (slide 3094, P.145.2, ELTE), chaetae in ventral bundles with surplus chaetae, preclitellarly. E. Paratype (slide 3093, P.145.1, ELTE), pharyngeal glands. F. Coelomocytes. G. Sperm funnel. H. Paratype (slide 3094, P.145.2). J. Paratype (slide 3094, P.145.2, ELTE). L. Paratype (slide 3093, P.145.1, ELTE). H–I. Multiple male glands (large primary bulb marked with black arrows, extra sexual glands marked with white arrows). J–L. Spermathecae. Scale bars = 50 μm.