Fridericia meridiana, Rota, 2015

Rota, Emilia, 2015, Five new species of Enchytraeidae (Annelida: Clitellata) from Mediterranean woodlands of Italy and reaffirmed validity of Achaeta etrusca, Fridericia bulbosa and F. miraflores, Journal of Natural History 49 (33), pp. 1987-2020 : 2005-2009

Fridericia meridiana sp. nov.

( Figure 7 ; Table 1)

Fridericia sp. 1, Rota et al. 2013, tables 1 and figure 3 (species ‘s17’); Rota et al. 2014, tables 1, 2 and Suppl. 1.

Type material

Holotype. MCZR Oligochaeta 0182, whole-mounted specimen, fully mature.

Type locality

Italy, Campania (Ca-2), Naples city, Capodimonte Park, a 134 ha historical urban park, positioned on the top of a hill in the northern part of the city (40.8717°N, 14.2519°E, 50 m asl). Holm oak trees with underbrush of Ruscus aculeatus , Hedera helix and, occasionally, Tradescantia fluminalis . Litter and dark humus on loose, coarse-textured soil with fragments of pyroclastic origin, moist, plot N 3, pH 6.4, 13.05.2009, E. Rota coll.

Paratypes. MCZR Oligochaeta 0183–0184 and SMNH Types 8725–8727, five wholemounted specimens from type locality and date.

Other material examined. Several specimens from type locality, 26.10.2009 and 20.06.2014, in the author’ s collection.

Etymology

From the Latin ‘meridianus’ (meaning = of midday, noon, southern), due to its apparent geographic distribution.

Diagnosis

Small quadrisetose species with four chaetae only present in some preclitellar ventral bundles, other bundles containing two or three chaetae; behind clitellum, bundles with three chaetae occurring ventrally in XIII–XIV, all other bundles bisetose. Segments 28–36, clitellar gland cells absent ventrally between and before male pores. Coelomocytes type b, peptonephridia type a, four pairs of preclitellar nephridia (6/7–9/10), chylus cells preclitellar. Male slits T-shaped, spermathecae with a small, sessile ectal gland, and bulb-shaped ampullae attached separately, on same or opposite sides of gut.

Description

Colour whitish. Live body length 5–6 mm, width about 0.16–0.17 mm at V, up to 0.19–0.20 mm at clitellum; fixed length 2.8–4.1 mm, width 0.14–0.17 mm at clitellum. Segment number 28–36, x = 31.8, s = 2.3 (n = 17). Prostomium ( Figure 7A ) rounded both in frontal and lateral views, pointing forwards, just as long as peristomium (40 μm after fixation), 50 μm high. Epidermal glands of irregular shape, inconspicuous, arranged in four transverse rows in anterior segments. Clitellum ( Figure 7B, D ) thin (6 μm), transparent, interrupted between and in front of male pores, annular elsewhere. Clitellar gland cells arranged in about 15 regular rows; dorsal and lateral sides mostly made of large hyalocytes (measuring 16–20 μm across when fixed); only granular cells on ventral side. Subneural glands on nerve cord absent.

Head pore at 0/1. Dorsal pores from VII. Spermathecal pores in ‘lateral lines’ at 4/5. Male pores as T-shaped slits with all three ‘arms’ of equal length ( Figure 7C ).

Chaetae 2,3 – 2: 2÷4 – (3),2, length in preclitellar bundles 25–40 μm, reaching maximal values caudally (50 μm). In fixed specimens, ectal tips of chaetae pointing posteriorly in anterior 15 segments, thereafter showing the opposite orientation. Only occasional detached chaetae in coelomic cavity.

Cuticle and body wall thin. No thickened septa. Brain ( Figure 7A ) soft-tissued, egg-shaped, in vivo up to 123 μm long, fixed 70–80 by 40 μm. Peptonephridia ( Figure 7H ) simple, unbranched, ending in anterior half of V (type a sensu Nielsen and Christensen, 1959). Pharyngeal glands three pairs, merging dorsally at 4/5 (widely) and 5/6 (partly), separate at 6/7, the latter pair with a small spur into VII ( Figure 7A ). Ventral lobes very small in IV, elongate in V, largest and bent upwards in VI. Four pairs of preclitellar nephridia (6/7–9/10), with efferent ducts arising midventrally from postseptal .

Coelomocytes ( Figure 7F, G ): in vivo nucleated cells with peripheral vesicles (type b), 18–32 μm long, anucleated corpuscles of various size, 5–12 μm long. Chloragogen cells from V , in vivo opaque, yellow-greenish. Chylus cells in IX–X or X–XI. Intestinal inner ridge extending over 4–6 segments between XIX–XXVIII (ventral intestinal ridge). Dorsal vessel originating in XIII–XIV. Four pairs of thin lateral commissures connect the dorsal vessel with the circumoesophageal commissures and the ventral vessel: two in III, one in IV and one in V.

Seminal vesicle absent. Sperm funnels ( Figure 7E ) very small, in vivo totally 75 μm long, 38 μm broad in proximal two-thirds, tapering distally. Collar narrower than body of funnel. Heads of spermatozoa about 24 μm long in vivo. Vasa deferentia 5–7 μm thick in vivo (narrower in distal course). Penial bulbs small, 55 μm long in vivo, 45 μm after fixation. One egg mature.

Spermathecae attached separately to gut, on same or opposite side of dorsal vessel ( Figure 7F ). Each spermatheca consists of a simple bulb-shaped ampulla (24 μm wide in vivo, 20 μm after fixation) and an ectal duct (160–175 μm long and 9 μm thick in vivo, 80 by 8–10 μm after fixation) endowed with a small sessile gland (16 μm long, 8–10 μm after fixation) at the external orifice. Sperm mass in a circle inside ectal lumen of ampulla.

Remarks

This species belongs to a group of small, quadrisetose Fridericia with bulb-shaped spermathecal ampulla, characterized by peripherally granular coelomocytes and short unbranched peptonephridia (see Cech and Dózsa-Farkas 2005). In particular, it resembles F. bretscheri Southern, 1907 in the texture of coelomocytes and number of preclitellar nephridia, but differs from it by the thinner body wall, the small spermathecal gland, the different chaetal formula, clitellar pattern, position of the chylus cells and shape of the male slits. In the latter features, it rather resembles F. composti Schmelz, 2003 , F. schmelzi Cech and Dózsa-Farkas, 2005 and F. semisetosa Dózsa-Farkas, 1970 , all of which however possess five pairs of preclitellar nephridia, comparatively larger anucleated coelomocytes and different chaetal formulae and clitellar patterns ( Table 1).

Distribution

The material described comes exclusively from Naples, Capodimonte, plot N3 (sexually mature both in spring and autumn). According to some old notes, possibly also found in Erice (Sicily).

Figures

Figure 7. Fridericia meridiana sp. nov. (A) Anterior body segments (dorsal view). The white arrow points to the small spur of the last pharyngeal glands into VII; (B) clitellum (dorsal view); (C) male pores and midventral interruption of clitellum between and before them; (D) lateral view of clitellum and male opening after fixation; (E) coelomic cavity of segments XI– XII, showing the minute sperm funnel; (F) dorsolateral view of segments IV–V, showing first two pairs of pharyngeal glands and the right spermatheca; (G) coelomocytes; (H) peptonephridium. (A) and (D) from permanent whole-mounted specimens; all others from live specimens. In all, anterior to the right.