Achaeta bohemica ( Vejdovský, 1879a )

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 : 1993-1996

Achaeta bohemica ( Vejdovský, 1879a)

Remarks on Achaeta bohemica ( Vejdovský, 1879a) sensu stricto This species was originally defined by Vejdovský (1879a) through just a couple of traits, to distinguish it from A. eiseni Vejdovský, 1878 , the only other congener then known. In A. bohemica the ‘chaetal glands’ (=flask-shaped glands) occurred only dorsally, against dorsal + ventral in A. eiseni , and the septal glands (=pharyngeal glands) were developed only in two segments, against three in A. eiseni . Five years later, in his ‘System und Morphologie der Oligochaeten’, the same author illustrated other features diagnostic of A. bohemica : the flask-shaped glands starting in IV, two secondary pharyngeal glands occurring ventrally in V and VI, the conspicuous oesophageal outer ridge (‘salivary glands’) dorsal on III–V, the dorsal vessel originating in VI, the intestine beginning in VII, nephridia present at 6/7 and with an expanded terminal vesicle ( Vejdovský 1884, plate 7, figure 1). Vejdovský never mentioned the reproductive organization of A. bohemica , except for the reciprocal position and paired condition of the testes and ovaries Anlagen.

Michaelsen (1889, p. 48 and figures 5–7; 1900) recorded A. bohemica in Hamburg (specimens about 15 mm long) and provided the first reproductive details: the clitellum ( Figure 2A ) interrupted dorsally and containing very large hyaline cells dorsolaterally, the male ducts opening ventrally through adjacent glandular bodies ( Figure 2A ), the spermathecae also opening close to the midventral line and consisting each of an elongate pear-shaped ampulla separated from the ectal duct by a valvelike occlusion. Černosvitov (1928), based on material from the Carpathians, extended the account of A. bohemica to include: cuticle 3.8 μm thick, clitellum over 1/2XII–1/ 2XIII, sperm funnels very long (l:w = 5–6:1), spermathecae reaching backwards X–XI and with ectal portion in V expanding before opening to the exterior through a perpendicular, ventrally directed thickened duct. Černosvitov (1928), however, reported the pharyngeal glands as three pairs at 4/5–6/7.

The picture emerging from the above accounts, provided that Vejdovský, Michaelsen and Černovitov referred to one and the same species, corresponds virtually in all details to Achaeta vesiculata Nielsen and Christensen (1959) , rightly declared a junior synonym of A. bohemica ( Vejdovský, 1879a) by Schmelz and Collado (2010). I collected and personally studied material of A. vesiculata in Ireland and Sweden (records already existed, respectively, by Healy (1979) and Backlund (1947 as A. bohemica )), and I observed in both countries the series of flask-shaped glands to start invariably in IV, the pharyngeal glands as well as the other somatic structures to be arranged as indicated by Vejdovský, and each penial organ to consist of a main glandular body plus minor glands in a longitudinal row. Schmelz and Collado (2010) suggest that the synonymy of A. bohemica sensu stricto should be extended to A. microcosmi Heck and Römbke, 1991 , because the latter’ s type material shows only two pairs of primary pharyngeal glands and nephridia at 6/ 7. It would be interesting to know where the flask-shaped glands start in the types of A. microcosmi (they were pictured in III by Heck and Römbke 1991, figure 1A).

Remarks on Achaeta bohemica sensu Nielsen and Christensen (1959) non Vejdovský

Achaeta bohemica as intended by Nielsen and Christensen (1959) differs from Vejdovský’ s taxon by having three pairs of well-developed primary pharyngeal glands, no secondary glands, dorsal vessel originating in VII ( Nielsen and Christensen 1959, table 4), no seminal vesicle, and spermathecae shorter and with ectal duct parallel to the long body axis. This combination of characters has gradually become recognized as ‘ Achaeta bohemica sensu Nielsen and Christensen, 1959 ’ ( Healy 1980; Rota and Healy 1994; Rota 1995; Standen et al. 2009; Schmelz and Collado 2010). Lately, however, while re-approaching the taxonomy of Achaeta in search of new information from permanent mounts, I discovered that two separate species occur in Italy that correspond to the above diagnosis and that I had confounded under one name.

One species – probably identical to the form ‘healyae’ of German authors (see Schmelz and Collado 2010), and that I leave unnamed – is similar to A. bohemica s.s. in all but the above-mentioned features. Thus, based on my material, its short portrait could be written as such: flask-shaped glands present dorsally from IV on, including XII, and absent ventrally. Clitellum one segment long (1/3XII–2/3XIII), dorsally interrupted, ventrally continuous, dorsolaterally made of 22 transverse rows of much enlarged hyaline gland cells, interspersed with few, small granular cells; the dorsal edges consist of a palisade of hyaline cells; only granular cells occur ventrolaterally. Male pores opening ventrally in XII, about 60 μm apart from one another, while spermathecal pores open ventrally at 4/5, 87 μm apart from one another. Oesophageal outer ridge seen dorsal on V. Two pairs of preclitellar nephridia, 6/7–7/ 8 constricted by septum. Coelomocytes 25–35 μm long, roundish or oval, with rugose surface, finely granular, pale but brownish when accumulated. Oesophagus expanding into intestine in 1/2VIII or at 8/9. Intestinal inner ridge ventral in XVIII–XXII. Sperm funnels 150–275 by 50–70 μm. Vasa deferentia 9–10 μm thick. Spermatozoa 60 μm long, heads 20–25 μm long. Penial bulbs compact, enclosed in a muscular sheath, 70 μm long. Spermathecal ampullae in VII–IX. Achaeta bohemica sensu Nielsen and Christensen, 1959 is common around Siena ( Rota 1995, sites Tuscany 5, 21, 25; Santi et al. 2010, sites 10 and 12; Rota et al. 2013, Villa Patrizia) and seems widely distributed throughout Europe. Judging from my slide collection it occurs at least also in Ireland (Co. Dublin: Larch Hill, UCD Campus, Kilternan; pers. obs.) and Algeria ( Rota and Healy 1994, p. 54).

Of the second species – herein described as A. giustii sp. nov. and distinguished by having a complete series of dorsal flask-shaped glands (i.e. from segment II to tail) and clitellum longer and reticulate – I have collected specimens only in Italian regions, and it could indeed be a Mediterranean endemic.

Figures

Figure 2. Achaeta bohemica (Vejdovský, 1879a) as illustrated by Michaelsen (1889). (A) Crosssection through segment XII, showing the conspicuous hyaline gland cells on the dorsolateral sides of the clitellum, the flask-shaped glands (b), and the glands surrounding the male openings (p); (B) arrangement of the longitudinal muscle fibres in the body wall; (C) intestinal epithelial cells of segment IX, showing their fine intracellular canals in cross (q) and longitudinal (l) section.