Achaeta giustii, 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 : 1996-1999

Achaeta giustii sp. nov.

( Figure 3 )

‘ Achaeta bohemica ( Vejdovský, 1879a) sensu Nielsen and Christ. 1959 ’, Rota 1995, p. 196 (partim).

‘ Achaeta cf. bohemica sensu Nielsen and Christ. 1959 ’, Rota et al. 2013, table 1 (species ‘s2’); Rota et al. 2014, tables 1, 2 and Suppl. 1 (partim).

Type material

Holotype. MCZR Oligochaeta 0176, whole-mounted specimen, fully mature.

Type locality

Italy, Tuscany (Tu-1), La Verna (Arezzo), centuries-old Abies alba and beech forest with young maple, Helleborus and Viola on bryozoal limestone (43.7065°N, 11.9319° E, 1120 m asl). Brown sandy humus and wood litter under rotten logs, moist, pH 5.9, 02.05.1996, E. Rota coll.

Paratypes. MCZR Oligochaeta 0177–0178, two whole-mounted specimens from Italy, Latium (La-1), 22.05.1994 . SMNH-Types 8721–8722, two whole-mounted specimens from Italy, Latium (La-2), 25.03.1992 .

Other material. One whole-mounted specimen from Italy, Tuscany (Tu-2), 29.10.1993. One alcohol-preserved specimen from Italy, Campania (Ca-1), 14.05.2009, in the author’ s collection .

Etymology

The new species is named for Prof. Folco Giusti, outstanding malacologist and dedicated zoogeographer, for his contributions to the knowledge of Mediterranean endemism.

Diagnosis

Medium-sized species, with large flask-shaped glands occurring dorsally from II to tail, including XII; clitellum over XII–1/2XIII, absent middorsally, hyaline and granular gland cells forming dorsolaterally a reticulate pattern; male pores in XII, penial bulbs compact, preclitellar nephridia two pairs at 6/7–7/8, spermathecae opening ventrally, ampullae reaching VII–IX.

Description

Live body length 6–8 mm, width 0.28–0.36 mm at XII; after fixation, length 4.2–5.8 mm, width 0.23–0.30 mm at XII. Segments 28–37. Large flask-shaped glands dorsally paired from II to tail, including XII ( Figure 3A, F ), absent ventrally; in vivo measured length throughout up to 120 μm, fixed 85–100 μm, glands smaller (50–75 μm) in II; dorsal distance between left and right glands 100–120 μm (fixed). Knob-like glands and lentiform glands absent. Clitellum in XII–1/2 XIII, dorsally interrupted (gap 90 μm wide), elsewhere continuous; dorsolateral sides made of polygonal granular and not much larger hyaline cells forming a reticulate pattern; dorsal edge consisting of granular cells ( Figure 3C ); only granular cells ventrally ( Figure 3E, F ); thickness of clitellum at midpoint 16–32 μm (fixed).

Head pore on prostomium. Spermathecal pores ventral at 4/5, 65–70 μm (fix) distant from one another. Male pores in XII, 50–70 μm apart, somewhat closer than spermathecal pores.

Cuticle at least 2.5 μm thick, in places reaching 6.0 μm, larger dorsally than ventrally. Brain about 150 μm long in vivo, 125–135 μm when fixed. Oesophageal outer ridge dorsal on III–V, inconspicuous. Pharyngeal glands three primary pairs at 4/5–6/7, each merging dorsally, no secondary lobes ( Figure 3B ). Two pairs of preclitellar nephridia at 6/7–7/8 constricted by septum, without swollen terminal vesicle; nephridia generally absent from first five postclitellar segments.

Coelomocytes of various size, with grooved but not granular cytoplasm, roundish, often with one to five marginal prominences, brownish when accumulated. Gut linear, without loops. Oesophagus gradually expanding into intestine at 7/8. Intestinal inner ridge extending over three segments between XVIII–XXIII (ventral intestinal ridge). Chloragogenous cells filled with fine granules. Dorsal blood vessel arising in VII ( Figure 3B ).

Seminal vesicle absent or small. Sperm funnels elongate equal to or shorter than body width, broadest point slightly below collar, length:width 3–4:1 (180–230 by 50–80 μm in vivo), generally bent at midlength; collar distinct, as wide or narrower than funnel ( Figure 3H ). Spermatozoa 50 μm long, heads 20 μm long. Vasa deferentia long and narrow (8–10 μm), tightly coiled. Penial bulbs small, compact, enclosed in a muscular sheath, 53–64 μm long in fixed worms ( Figure 3E, F ). One egg mature. Spermathecal ampullae reaching to VII–IX, ectal ducts almost parallel to long body axis in vivo, more contracted on one side (thus bent at an obtuse angle) in fixed specimens ( Figure 3G ); ectal ducts not tapering towards pore, rather appearing glandular at junction with body wall.

Remarks

This species belongs to the group of Achaeta with only dorsal flask-shaped glands and spermathecae opening ventrally. While alive it looks similar to ‘ Achaeta bohemica sensu Nielsen and Christensen, 1959 ’, it can be recognized (more easily after fixation) by having a complete series of dorsal flask-shaped glands (i.e. from segment II to tail) and clitellum longer and reticulate, with granular gland cells bordering the dorsal edges (see above).

Distribution

Apparently endemic to the Mediterranean region , recorded in Italy from Tuscany to Campania.

Figures

Figure 3. Achaeta giustii sp. nov. (A) Cephalic region (lateral view); (B) dorsolateral view of segments I–VIII, showing the well-developed pharyngeal glands; (C) dorsal view of clitellum. Note the granular cells bordering the middorsal interruption (dg); (D) shallow lateral view of body wall (segment IX), revealing the lozenge pattern of the longitudinal muscle fibres; (E) lateral view of clitellum, showing the reticulate pattern of the gland cells; (F) lateral view of same clitellum in a deeper optical section, documenting its midventral continuity and middorsal gap; (G) ectal portion of the spermatheca; (H) sperm funnel. All from permanent wholemounted specimens, anterior to the left.