Enchytraeus krumbachi ( Čejka, 1913 ), CE, 1689

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 : 24-27

Enchytraeus krumbachi ( Čejka, 1913)

Figs 1B , 7–8 , Tables 1–2

Enchytraeus krumbachi Cejka, 1913: 145–151 , figs 1–10.

Enchytraeus krumbachi – Erséus et al. 2019: 126–129 , fig. 12.

Emended diagnosis

As a result of our comparisons, we suggest the following diagnosis of the species:

(1) Body length 15–25 mm (in vivo), segment number 40–66; (2) chaetae maximum 4 (5, 6) per bundle; (3) granulocytes and hyalocytes irregularly arranged dorsally in clitellum; (4) four pairs of nephridia preclitellarly; (5) the pharyngeal glands are connected dorsally; (6) dorsal blood vessel origin from XV, blood colourless; (7) sperm funnel 1.2–3 × as long as wide (fixed); (8) vasa deferentia tripartite, extending into XIV–XIX, the middle part thicker, unciliated, the thinner part ciliated; (9) male copulatory organs: one large rounded primary bulb, slightly longer than wide (80–100 μm × 70–90 μm), many smaller secondary glands; (10) ampulla of spermatheca rounded, large, without diverticula, ectal duct with large glands covered; (11) 4–10 mature eggs present at a time.

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

Material examined

ITALY • 11 specs (+ 12 specs only in vivo); Castiglione seashore ; ID 1383, 1385 , slide 2867 to 2869, 2872, 3004, 3006 to 3007, 3014 to 3015 ; ELTE • 3 specs; Punta Ala Grosseto ; slide 3174, 3180 to 3181 ; ELTE .

Description of new material and comparison with previous accounts

Morphological characters identical with the description by Čejka (1913) and Erséus et al. (2019). Unfortunately, we did not have the opportunity to study the type material, but the original description is quite detailed and can be compared with our own data.

MEASUREMENTS. Segment number 40–66. In vivo, body length 15–25 mm, width at clitellum 700– 950 μm; when fixed, length 7–14 mm (with first 12 segments 2.7–3.8 mm), width 500–860 μm. Čejka (1913) originally reported 66–75 segments, and body ca 15 mm long, and Erséus et al. (2019), studying fixed worms, noted length of 2.9–3.8 mm for first 12 segments, and width of 400–620 um at clitellum. Thus, our specimens are roughly identical in general size to earlier studied material, although slightly wider than individuals examined by Erséus et al. (2019).

CHAETAE. Chaetal formula: 2,3–2,3:2,3,4,(5,6)–2,3. In ventral preclitellar bundles of some specimens 3 chaetae, and only one or two bundles with 4 chaetae, in other specimens 4 chaetae in all or most bundles; sometimes 2–3 surplus chaetae can be found. In Erséus et al. (2019), chaetal formula 3–2:3,4–2 and there are always 2 chaetae per bundle postclitellarly. Some of our individuals with 3 chaetae per bundle postclitellarly. In one specimen, 5 and 6 chaetae occured in some preclitellar ventral bundle. Čejka mentioned 3 chaetae in lateral and 4 chaetae in ventral bundles. Size of chaetae similar to size given by Erséus et al. (2019) ( Table 2 ). 2–3 surplus chaetae also occasionally occur ( Fig. 7A ).

COELOMOCYTES. Round or narrowed at one end, texture granulated, 15–27 μm length in vivo ( Fig. 7B ), (fixed not well measurable) Erséus et al. (2019): 10–15 μm, fixed. Shining, hyaline corpuscles mostly absent, but in some specimens occuring in few numbers.

CLITELLUM. Granulocytes and hyalocytes irregularly arranged dorsally ( Fig. 7C ). In Erséus et al. (2019), ventral surface of XII with invaginations creating two recesses with overhanging lips. In our specimens near to male copulatory glands laterally ( Fig. 7D ) and ventrally between lips and midventrally only granulocytes ( Fig. 7E ). Čejka (1913) does not give any description of epidermal gland cells of epidermis.

PHARYNGEAL GLANDS. In Erséus et al. (2019), pharyngeal glands are connected dorsally, in our individuals the position is mostly the same ( Fig. 7F ), but sometimes the first and second pairs of primary pharyngeal glands did not connect or they just contacted ( Fig. 7G ). In an unusual way, the third pair of pharyngeal glands was completely absent in one specimen.

NEPHRIDIA. Four pairs of preclitellar nephridia at 6/ 7–9 / 10.

SPERM FUNNELS. Length: width ratio of sperm funnel ( Fig. 7I ) 1.2–3:1 (fixed), ( Erséus et al. 2019: 1.5–2:1, Čejka 1913: 3:1). Vas deferens ( Fig. 8A–B ) has same structure, tripartite, middle part thicker (55–75 μm with 20–30 μm wall thickness), unciliated, thinner ductus 20–37 μm thick and ciliated. Sizes of thicker part of ductus slightly larger than given by Erséus et al. (2019) (50–55 μm, with 15 or 15–30 μm wall thickness). In Erséus et al. (2019), vas deferens reaches XVIII, in our specimens variable: XIV–XIX, in Čejka (1913), it reaches XVI.

SPERM SACS. Well developed, paired sperm sacs ( Figs 7H , 8C ) in IX–XI.

MALE COPULATORY ORGANS. One large rounded primary bulb, slightly longer than wide (80–100 μm × 70– 90 μm), according to Erséus et al. (2019): diameter 85–90 μm and many smaller secondary (accessory) glands ( Fig. 8D–E ). In Čejka (1913), 6 gland complexes around penial bulb.

SPERMATHECAE ( Figs 1B , 7F–G , 8F–H ). Without diverticula, ampulla round, large [70–140 μm, in Erséus et al. (2019): 95–125 μm], ectal duct with large glands covered ( Figs 1B , 8F–H ). In Erséus et al. (2019), ectal duct of spermatheca entally opening into small rounded chamber but we did not observe this chamber, and it is not mentioned in Čejka’s original description. Besides, differences in length and diameter of ectal duct (see Table 2 ). According to the morphological comparisons above, we think that our specimens agree better with the morphological description of Čejka (1913).

Distribution and habitat

Castiglione seashore, Ligurian Sea, Italy, decaying seagrass debris. 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. 7. Micrograph of Enchytraeus krumbachi (Čejka, 1913). A–B, D–F, H–I. In vivo. C, G. Fixed, stained. A. Chaetae in ventral bundles preclitellarly (surplus chaetae marked with arrow). B. Coelomocytes. C. Clitellar glands, dorsal view (slide 2868, ELTE). D. Clitellar glands, lateral view (near to male copulatory apparates more granular glands).E. Between the two male copulatory apparates (marked with arrows) and middle ventrally only granulocytes. F–G. Pharyngeal glands (in F first and secondary glands connected dorsally, in G these glands near to each other but not connected dorsally, the spermathecae marked with arrows).G. Slide 2867 (ELTE). H. Sperm sacs in X–XI. I. Sperm funnel. Scale bars = 50 μm. Abbreviation: sf = sperm funnel.

Fig. 8. Micrograph of Enchytraeus krumbachi (Čejka, 1913). A–B, D, F. In vivo. C, E, G–H. Fixed, stained. A–B. Sperm ducts (thick-wall portion marked with black arrow, thin-wall portions marked with white arrows). C. Large sperm sacs with more lobes (slide 2868, ELTE). D–E. Male copulatory apparates (many accessory glands marked with arrows). E. Slide 2868 (ELTE). F–H. Spermathecae (ampulla rounded without diverticula). G. Slide 2867 (ELTE). H. Slide 2872 (ELTE). Scale bars = 50 μm. Abbreviation: pbc = primer gland.