Fridericia rara, 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 : 2014-2017

Fridericia rara sp. nov.

( Figure 9 ; Table 2 )

Fridericia sp. 2, Rota et al. 2013, table 1 (species ‘s19’); Rota et al. 2014, tables 1, 2 and Suppl. 1.

Type material

Holotype. MCZR Oligochaeta 0185, 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, pH 7.0, plot N 1, 13.05.2009, E. Rota coll.

Paratypes. MCZR Oligochaeta 0186–0187, two whole-mounted specimens, fully mature, from type locality and date .

Etymology

Named for its very unusual features, including the unique chaetal formula and the small complement of preclitellar nephridia.

Diagnosis

Small quadrisetose species with a unique chaetal formula (0,2 – 2: 2÷4 – 2), clitellar gland cells mostly hyaline and large, completely absent ventrally between and before male pores, coelomocytes hyaline (type a), peptonephridia type a, only three pairs of preclitellar nephridia, chylus cells in XII–XIV, dorsal blood vessel from XV, sperm funnels small, barrel-shaped, male slits longitudinal, each resembling a squared parenthesis, enclosing on its inner side the glandularized male pore, which appear as a small star-like formation (modiolus in Schmelz’ s terminology), spermathecae with bulb-shaped ampullae and a small sessile ectal gland.

Description

Colour whitish. Live body length 5 mm, width 0.25 mm at clitellum; fixed length 3.0– 3.8 mm, width 0.15–0.16 mm at clitellum. Segment number 27–32 (n = 3). Prostomium ( Figure 9A ) rounded both in frontal and lateral views, pointing forwards, just as long as peristomium (35 μm after fixation), 50 μm high. Epidermal glands arranged in three rows, more developed lateroventrally (only one seen in dorsal view). Clitellum ( Figure 9B, C ) up to 10–14 μm thick, interrupted between and in front of male pores, annular elsewhere. Hyaline and granular gland cells in about 20 chequered rows, hyaline cells larger (13–19 by 11–13 μm), elongate transversely, present also behind male pores. 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 in vivo as longitudinal slits, each resembling a squared parenthesis, enclosing on its inner side the glandularized male pore, which appears as a small but distinct star-like formation (modiolus in Schmelz’ s terminology); in fixed specimens each male pore appears simply surrounded by a small rosette ( Figure 9C, D ).

Chaetal formula 0,2 – 2: 2÷4 – 2, i.e. lateral bundles absent in II, bisetose elsewhere; ventral bundles with three or four chaetae in some preclitellar bundles, bisetose elsewhere. Maximal chaetal length 32–35 μm, both before and after clitellum. In fixed specimens, ectal tips of chaetae pointing posteriorly before clitellum, thereafter showing the opposite orientation. Only occasional detached chaetae in coelomic cavity.

Cuticle and body wall thin. No thickened septa. Brain ( Figure 9A ) 80 μm long when fixed (n = 3). Peptonephridia simple, unbranched, ending in anterior part of V (type a sensu Nielsen and Christensen 1959). Pharyngeal glands ( Figure 9A ) three pairs, merging dorsally at 4/5 (widely) and 5/6 (partly), adjacent at 6/7. Ventral lobes absent in IV, middle-sized in V– VI. Only three pairs of preclitellar nephridia (6/7–8/ 9), with efferent ducts arising midventrally from postseptal ( Figure 9A ) .

Coelomocytes: in vivo nucleated cells hyaline (type a), fixed length 24–30 μm, anucleated corpuscles medium to small, fixed length 2.5–6 μm. Chloragogen cells from V . Chylus cells in XII–XIV ( Figure 9G ). Intestinal inner ridge ventral in XXII–XXVI. Dorsal vessel originating in XV. Four pairs of thin lateral commissures connect the dorsal vessel with the circumoesophageal commissures and the ventral vessel: two (with close roots) in III, one in IV and one in V.

Seminal vesicle absent. Sperm funnels ( Figure 9D ) barrel-shaped, 88 μm long and 50 μm wide in vivo, 56–67 by 45–56 μm after fixation. No distinct collar. Heads of spermatozoa about 40 μm long in vivo. Vasa deferentia 5 μm thick when fixed. Penial bulbs 50 μm long after fixation. One egg mature.

Spermathecae ( Figure 9F ) with ectal ducts 112 by 10 μm after fixation (diameter 14 μm in vivo), each with a small (8 μm fixed), sessile ectal gland and bulb-shaped ampullae, 45 μm across (32 μm after fixation), containing a circle of sperm, attached close to one another to gut. In one paratype, spermatheca on the right attached to gut in VI .

Remarks

Among all Fridericia species, F. rara sp. nov. is distinguished by a set of unusual traits: a unique chaetal formula, an unprecedented reduction of preclitellar nephridia (also F. lacii Dózsa-Farkas, 2009 has only three pairs of preclitellar nephridia, but positioned at 7/8–9/10), and a peculiar shape of the male openings. Compared with the other Fridericia species with bulb-like spermathecal ampullae, simple peptonephridia and hyaline coelomocytes, F. rara appears closest to F. bulbosa s.s., with which it shares the quadrisetose ventral pattern ( Table 2 ).

Distribution

Only known from Naples, Capodimonte plot 1, in spring.

Figures

Figure 9. Fridericia rara sp. nov. (A) Anterior body segments (dorsolateral view), showing the pharyngeal glands, the left spermatheca and the preclitellar nephridia; (B and C) details of clitellum on its dorsal (B) and ventrolateral sides (C). Note the absence of gland cells ventrally in XII. Squared contour on midventral interruption indicates the position of (D). (D) Close-up of male pore; (E) sperm funnel; (F) lateral view of segments IV–V, showing the left spermatheca; (G) chylus cells showing through intestinal wall in segments XIII–XIV. All from permanent whole-mounted specimens, anterior to the left.