A new oribatid mite belonging to the family Ceratozetidae is described from the province of Biscay in the Basque Country, Northern Spain, being the second species for this genus in Palearctic Region. Edwardzetes ubali is proposed for this new species and main differences among the remaining Edwardzetes are presented in this paper.
INTRODUCTION
Two ceratozetid adult individuals belonging to one species have been found in samples of a research dealing with effects of non prescribed fires on oribatid mites of Biscay (Northern Spain). The species can be identified within the genus Edwardzetes and is close to E. edwardsii (Nicolet, 1855) which has been, up to now, the only representative known in the Ibero-Balear area and in the remaining part of the Occidental Europe (Pérez-Iñigo, 1993). E. edwardsii has been recorded in Spain by Moraza et al. (1980) in the Pyrenees of Navarra. Our species differs clearly from E. edwardsii mainly in size, sensilli, lamellar cusps, rostrum and notogastral setae. These differences have been considered enough to describe it as a new species record for science. The specific name of the new species is chosen due to the place where it appeared.
DESCRIPTION
Material
Two individuals (male and female) were found in the sample labeled as ‘16sb’ at the locality of Carranza (The Ubal Mountain: UTM 30TVN667806, western Biscay Province, Northern Spain) in 29 May 1992. Both specimens were dissected to be studied and preserved on labelled slides in Hoyer medium. The male was designated as holotye and the female as paratype. All the individuals are deposited in the Acarology Collection of the Department of Zoology of the Faculty of Sciences, The Basque Country University (Spain), with the serial number 348.
Colour and dimensions
Dark brown. Holotype (male) 920 μm length and 630 μm width. The female (paratype) 965 μm length and 625 μm width.
Prodorsum
Rostrum truncated, showing a trilobulated dorsal aspect because of a tongue-like wider middle part (Fig. 2A) while rounded in other Edwardzetes species (Table 2). Extreme teeth (Fig. 2B), in dorsal view, not so marked as in Edwardzetes edwardsii (Fig. 3B). Lamellae long, ending in very small but conspicuous lamellar cusps. Rostral setae (ro) of middle size, not very thick, barbed and slightly incurved. Lamellar setae (le) not very long, thin and barbed, extending forwards beyond the prodorsum. The interlamellar setae (in) as lamellar ones, reaching the rostral margin. Sensillus (ss) with thin long stalk and lanceolated head (Fig. 2C). Exobotridial setae (ex) of middle size and lightly barbed.
Notogaster
Anterior border gently curved, almost as wide as long. Pteromorphae prominent, immovable type (Balogh and Balogh, 1992). Four pairs of porosae areae are present, Aa the biggest one. Ten pairs of notogastral setae (N) fine, long and without barbation, some of their tip slightly undulated, c2 the longest one (Fig. 1A).
Ventral Region
Six pairs of moderately long genital setae (g). A single pair of aggenital setae (ag). Two pairs of anal (an) and three pairs of adanal setae (ad) are present, of which the pair ad3 is in paranal possition, as well as the fissurae iad are. Epimeral formula (3-1-3-3) (Fig. 1B).
Gnathosoma
Chelicerae normal type. Palps presenting regular setation (0-1-2-9) from femur to tarsus. Here it is observed one of the distinguishable feature of the family Ceratozetidae referring to the close union between the anterocuminal eupathidium acm and solenidion ω forming a double horn structure, named by Grandjean (1954) ‘la corne double’.
Legs
All legs tridactyle, presenting some heterodactyly and characterized for their setal length and its fine barbation. The setal formula for each leg summarized in Table 1. Tarsal setation is the same as Grandjean (1940) described for the species Edwardzetes edwarsii, and the solenidial formula is as Grandjean (1946) decribed for the same species. Neither femora nor genu have ventral crests or tooth-like projections as in some species of Edwardzetes.
Table 1
Edwardzetes ubali n.sp.: setae and solenidia of legs.
Table 2
Main identifying characters in the genus Edwardzetes:
LEG I. (Fig. 4A). On the tarsus the famulus ε located between solenidia ω1 and ω2, the second solenidion ceratiform (Norton, 1977) and of middle length (ω1 lost). Fastigial seta ft′ much longer than ft″. Solenidia of tibia arranged close to each other, ϕ2 long and setiform (ϕ1 lost). On the femur dorsal setae (d) not so thick, but very long; ventral setae bv″ very fine, long and without barbation, while the ventral one v″ is much longer, setiform and barbed.
Fig. 4
Edwardzetes ubali n. sp. Legs in paraxial face: A: leg I left, B: leg II left, C: leg III right, D: leg IV right. (bar scale 100 μm)
LEG II. (Fig. 4B). Solenidia of tarsus ω1 and ϕ2 long, more or less equal in length, ceratiform and separated from each other. Fastigial setae (ft) long, equal in length, not very thick and barbed. Subunguinal seta (s) thick and long, quite different from that of the other tarsi, thicker than the homologous one described by Grandjean (1940) for E. edwardsii.
LEG III. (Fig. 4C). Fastigial setae thick and long. Solenidion (ϕ) on tibia ceratiform, longer than the baculiform one (σ) on genu.
LEG IV. (Fig. 4D). All setae in general, long, thick and barbed. Single fastigial seta ft″ in tarsus long and barbed. Iteral setae (it) absent.
DISCUSSION
The individuals can be identified as Edwardzetes fitting perfectly well into the features of the genus (Balogh and Balogh, 1992) although a very small but conspicuous lamellar cusps are present (Fig. 2A), not so well developed as in Ceratozetes. Other features confirming the position of our individuals into Edwardzetes are: large size and narrow tutorium without little distal tooth and without large pointed ending. The main important features to distinguish species within Edwardzetes are those given in Table 2, in which it can be seen that the closest species for the new one is E. edwardsii.
Some other differences between E. ubali and E. edwardsii can be commented on. Rostrum is truncated in both species, showing a trilobulated appearance in dorsal view because of a tongue-like wider middle part, but in E. ubali the extremeteeth are not so marked, while in E. edwardsii those ones are more pointed (Alberti et al., 1992). It must be stated that in other species of the genus the rostral shape has been described as rounded, feature that absolutely differs from the mentioned before.
Referring to leg setation, E. ubali presents the same tibial formula as that Grandjean (1940) described for E. edwardsii, as well as the same solenidial one (Grandjean, 1946). These data differ from those presented by Stary and Block (1995) for the species E. australis. The absence of projection on genu II is also another feature coinciding with E. edwardsii but differing from the other species of the genus. This structure on genu II appears to resemble a very thick and great spine in some Edwardzetes (Table 2). Subunguinal seta (s) of tarsus II is quite different from that of the other tarsi, thicker than the homologous one described by Grandjean (1940) for E. edwardsii. Edwardzetes is not a very common genus and it prefers moist media, mainly mosses. Up to now E. ubali is the largest species within the genus Edwardzetes.
Acknowledgments
We are grateful to Dr. R.A. Norton for allowing us using his database in locating species and bibliography and also to Dr. L.S. Subías for his help in identifying the specimens and making comparisons with other species. We want to thank the referees for their suggestions to improve our manuscript. This study has been supported by CICYT (Comisión Interministerial de Ciencia y Tecnología, Spain), Project number FOR91–1091.
