Enchytraeus andrasi, 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 : 13-19

Enchytraeus andrasi sp. nov.

urn:lsid:zoobank.org:act:5E2BFD02-E8F8-4689-95F1-57E3A7B01A61

Figs 1C–D , 4 , Tables 1–2

Diagnosis

(1) Body length 11–14 mm (in vivo), segment number 29–34; (2) chaetae maximum 3 per bundle, straight with ental hook; (3) clitellum in XII–XIII, hyalocytes and granulocytes irregularly arranged dorsally and laterally, ventrally absent between the male lip-like folds; (4) four pairs of nephridia preclitellarly; (5) all pharyngeal glands connected dorsally with ventral lobes, the third pair may be free; (6) dorsal blood vessel origin from XIV, blood colourless; (7) sperm funnel cylindrical, 380–580 μm long, 3–5 × as long as wide (in vivo); (8) vasa deferentia uniform, 24–25 μm wide with 8 μm thick wall (fixed), ciliated, not extending beyond XIII; (9) male glands multiple: one large rounded primary bulb, diameter 50–70 μm (fixed), and many smaller secondary glands; (10) spermathecal ectal duct (50–85 μm long, fixed) covered with gland cells, ampulla irregularly sac-like, about 100–106 μm wide with one large diverticulum (80–100 μm long, fixed), connecting with oesophagus; (11) more small mature eggs present at a time.

Etymology

Named in the honour of the brother of Klára Dózsa-Farkas, András Dózsa-Farkas, who collected the sample with this species.

Material examined

Holotype

ITALY • last 14 segments, 3.4 mm used for DNA analysis ( No. 1386 , ID number); Ligurian Sea, Castiglione seashore, decaying seagrass debris ; 42°45′56.0″ N, 10°52′51.0″ E; 13 Dec. 2019; András and Kinga Dózsa-Farkas leg.; slide 2871 , En.3; ELTE.

Paratypes

ITALY • 1 spec., last 9 segments, 1.65 mm used for DNA analysis ( No. 1390 , ID number); same collection data as for holotype; slide 2870 , P.144.1; ELTE • 1 spec., last 9 segments, 1.65 mm used for DNA analysis ( No. 1391 , ID number); same collection data as for holotype; slide 2873 , P.144.2; ELTE .

Description

MEASUREMENTS. Medium-sized to large specimens. Holotype 14.3 mm long, 470 μm wide at VIII and 600 μm at clitellum in vivo, 9.3 mm long, 330 μm wide at VIII and 420 μm at clitellum, when fixed, 41 segments. Body length of paratypes 11–12 mm, width 430–450 μm at VIII and 550–680 μm at clitellum, in vivo. Length of fixed specimens 6.7–8.1 mm, width 420 μm at VIII and 470–580 μm at clitellum. Length of the first 12 segments 2.5–2.6 mm, after fixation. Segment number 29–34.

CHAETAE. Chaetal formula: 3–2,3:3–2,3. Chaetae straight with ental hook, about equal in size within bundle, 60–62 μm × 4 μm preclitellarly and 67–75 μm × 4–5 μm posteriorly. Often 2–3 surplus chaetae near bundles ( Fig. 4B ). Chaetae in XII absent ventrally, but present laterally, 2 per bundle.

HEAD PORE. At 0/I.

EPIDERMAL GLANDS. Inconspicuous.

CLITELLUM. In XII–XIII, hyalocytes and granulocytes irregularly arranged dorsally and laterally ( Fig. 4C ), ventrally absent between male lip-like folds ( Fig. 4E ). Before and behind some glands but few.

BRAIN ( Fig. 4A ). About 1.8–2 × as long as wide, truncate posteriorly, sides slightly merging anteriad.

OESOPHAGEAL APPENDAGES. Pair of blind-ending tubes. In two specimens all primary pharyngeal glands connected dorsally, with ventral lobes ( Fig. 4D ), but in third specimen last pair free dorsally.

DORSAL BLOOD VESSEL. From XIV, blood colourless. Anterior bifurcation in I.

NEPHRIDIA. Four pairs of preclitellar nephridia from 6/ 7–9 /10, anteseptale funnel only, postseptale bulged, short efferent duct, originating postero-ventrally ( Fig. 4F ).

COELOMOCYTES. Oval, texture granulated, about 18–25 μm long, in vivo. No shining, hyaline corpuscles.

SUBNEURAL GLANDS. Absent.

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

SPERM FUNNELS. Large, 380–580 μm long, 3–5 × as long as wide in vivo (235–330 μm long and 2–2.5 × as long as wide, fixed). Collar slightly narrower than funnel body ( Fig. 4H ). Vasa deferentia long, irregularly coiled in XII–XIII, about 24–25 μm wide with 8 μm thick wall (fixed), ciliated ( Fig. 4G, I ).

SPERMATOZOA. Not measurable, heads about 21–36 μm, in vivo.

MALE COPULATORY ORGANS. Male glands multiple: one larger rounded primary bulb (diameter 50–70 μm, fixed) near male pore, and many smaller (32–78 μm long and 18–24 μm wide, fixed) secondary glands. Glands arranged roughly in semicircle around male pore and primary bulb (diameter 180–250 μm, fixed) ( Fig. 4J ). Male pores covered by lip-like folds (about 80 μm wide), recess present.

SPERMATHECAE ( Figs 1C–D , 4K ). With short ectal duct (50–85 μm long, fixed), covered with gland cells (50–75 μm widely in vivo and fixed equally), canal 4–6 μm wide. Ampulla irregularly sac-like, about 100–106 μm wide, heads of spermatozoa embedded in wall of ampulla. Ampulla with one large diverticulum (80–140 μm long, 40–68 μm wide, fixed) ( Fig. 1C ), in one case ampulla also with small diverticula-like protrusions ( Figs 1D , 4K ). Ental duct short and opens into oesophagus separately. More small mature eggs present at a time ( Fig. 4I ).

Differential diagnosis

In the new species, like as in four of the species in the E. albidus complex ( E. albidus s. str., E. moebii , E. polatdemiri and E. irregularis of which sequences are available, the vasa deferentia approximately uniform and ciliated throughout. The principal differences are that the spermathecal ampullae have diverticula in the new species but neither E. moebii nor E. polatdemiri have it. Besides E. moebii is much larger than the new species (body length 25–35 mm with segment number 60–74 vs 6.7–9.3 mm 29–41) and has more chaetae in ventral bundle (4–5 vs 3). Although in E. irregularis the spermatheca has also diverticulum and the maximum number of chaetae is 3, but E. irregularis is larger than the new species (length 9–13 mm with segment number 47–76), and the blood is pink (in E. andrasi sp. nov. colourless) and has extra copulatory glands. Morphologically, E. albidus s. str. is most similar to the new species taking, the form of the spermatheca into consideration, but differs from it in size (10– 13 mm with 58–69 segments vs 6.7–9.3 mm and 29–41 segments) and in the maximum number of chaetae (4–5 vs 3) and the sperm duct extends into XIV–XX (vs only in XII–XIII). The new species is also similar to E. andrasiformis sp. nov., with the morphological differences listed in the differential diagnosis of the latter species.As shown below, E. andrasi is clearly distinguished as separate from all other species by genetic data, which also give strong support for E. andrasi being most closely related to E. andrasiformis , described below.

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

Distribution and habitat

Castiglione seashore, Ligurian Sea, 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. 4. Micrograph of Enchytraeus andrasi sp. nov. A–C, E, G–I, K. In vivo. D, F, J. Fixed, stained. A. Brain. B. Chaetae in ventral bundles preclitellarly (surplus chaetae marked with arrow). C. Clitellar glands of holotype, dorsal view. D. Paratype (slide 2870, P.144.1, ELTE), pharyngeal glands. E. Clitellar glands of holotype, ventral view (male lip-like folds marked with arrows, between the folds the glands absent: marked with *). F. Paratype (slide 2870, P. 144.1, ELTE), nephridium at 7/. G. Sperm duct. 8 H. Sperm funnel. I. Sperm duct and many small eggs. J. Holotype (slide 2871, En.3, ELTE), multiple male glands of holotype (large primary bulb marked with arrow). K. Spermatheca (large diverticulum marked with short black arrow, small diverticula like protrusions marked with white arrows, ectal duct covered with glands marked with long, black arrow). Scale bars = 50 μm.