Epidamaeus sp.

Miko, L. & Monson, F. D., 2013, Two Interesting Damaeid Mites (Acari, Oribatida, Damaeidae Berlese, 1896) From The British Isles And Svalbard (Spitsbergen, Norway), With A Description Of Kunstidamaeus Arcticus N. Sp., Acarologia 53 (1), pp. 89-100 : 94-99

Epidamaeus sp. ( aff. floccosus Behan-Pelletier and Norton, 1985 )

( Fig.4-7 )

This species of Epidamaeus resembles the species Epidamaeus floccosus Behan-Pelletier and Norton, 1985 (see discussion below), but bears also some differing characters, namely a conspicuous transverse ridge behind the prodorsal tubercles Ba; elongated anterior parastigmatic apophyse Sa; spinae adnatae with lateral dents; and smooth, long notogastral setae inserted on cuticular thickenings. These characters would allow to establish a new species within Epidamaeus . However, taking into account that we had only a single, even slightly damaged, individual available, it was impossible to decide on stability and variability of the characters. Therefore, the potential decision on the specific status is left for later until broader material is available.

Description of the adult.

Material examined — Single individual (female), collected by F.D. Monson from rotting straw, situated just within the shelter of a Dutch barn with open aspect, Barn Hey Farm, Tarbock Green, south Lancashire, England, sample OR 908, 10 th Oct 2009 .

Measurements — Body length 520 µm, prodorsum length 200 µm, prodorsum largest width (at the level of the posterior end of bothridia) 192 µm, notogaster width 325 µm.

Acarologia 53(1): 89–100 (2013)

Integument — Body covered by cotton-like filamentous cerotegument in the sejugal area and laterally around leg insertions. Cuticle of prodorsum smooth, with notogaster finely granulated. Ventrally, with net-like pattern on the mentum, epimeres I-II and genital plates. Cuticle of all femora and trochanters II-IV with a distinct ’netlike’ pattern.

Prodorsum ( Figs. 4A , 5 A-B, D-E, 6A-E) — Regularly triangular in shape, with lateral part above insertions of legs II rounded and without an apophysis P. Proximal part of trochanters I and II covered by the tectum, projecting laterad and lateroposteriad from the lateral part of prodorsum ( Fig. 5D ). Parastigmatic apophyses very different in shape; anterior apophyse Sa prolonged, narrow, pointed, perpendicular to the body axis, about four times longer than Sp, which is short, triangular, blunt and pointing anteriad ( Fig. 5E ). Anterior postbothridial tubercles (Ba) present, distinct but relatively small and opposed posteriorly by a broad, transverse, transparent ridge. Rostrum broadly rounded, with an indistinct, broad central lobe. Short, indistinct oblique ridges present latero-anteriorly to insertion points of lamellar setae. Similarly, short ridges present laterally, behind insertions of leg I, projecting anteriad from bothridial area. Both structures combined together slightly resemble lamellar ridges present in other oribatids. Prodorsal setae fine and relatively long; rostral and lamellar setae unilaterally with small, hardly visible spines; other prodorsal setae smooth. Lamellar setae (75 µm) slightly longer than rostral (58 µm). Exobothridial setae strongly curved, fine, and slightly shorter than ro (50 µm) ( Figs. 6 C-E). Interlamellar setae clearly the most robust on the prodorsum, nevertheless, both broken and missing distal part. Remaining basal part around 37 – 40 long, overall length is difficult to judge, but it is assumed they may reach about 60-80 µm ( Fig. 6B ). Bothridium typical of the

C – rostral seta; D – lamellar seta; E – exobothridial seta; F – notogastral seta c1; G – notogatsral seta la; H – notogastral setae ps1-ps3 (from right to left) (scale bar = 50 µm).

Damaeidae , funnel-like, with a transparent, round and expanded rim. Sensillus smooth, elongate, setiform, attenuated distally, without a flagellate tip; about 140 µm long ( Fig. 6A ).

Notogaster ( Figs. 4A , 5G , 6 F-H) — Circular, with strong, medium long spinae adnatae, both distally with strong, lateral teeth ( Fig. 5G ). Notogastral setae fine, smooth and relatively long (c1 and c2 about 75 µm), some, however, with broken distal parts, with lm, lp (one side only) broken in part, or completely ( Figs. 4A , 6 F-G). All notogastral setae inserted on cuticular thickenings, forming small tubercles or short ridges, and more pronounced on posterior part of notogaster. Proximal part of setae, near insertion points, slightly narrower and more transparent than remainder of setae. Setae of ps series finer and shorter than remainder, ps2 about 50 µm with ps3 about 25 µm long ( Fig. 6H ). Lyrifissures normally developed; openings of notogastral glands well visible, with a small "cap" of a transparent secretion. A pair of pores present in posterior central part of notogaster, axial to insertions of setae lp.

Ventral characters ( Figs. 4B , 5F ) — Gnathosoma normal for the Damaeidae ; mentum relatively broad, setae h about 25 µm long, setae m slightly, but distinctly shorter. Tectum of podocephalic fossa simple, with an angular, blunt, external tip, hardly projecting over lateral edge of ventral plate. Enantiophyse E2 absent, with only a slight thickening visible in this area. Ventrosejugal enantiophyse well developed, positioned laterally, close to the parastigmatic apophyses. Va slightly stronger than Vp, with both apophyses dentiform, triangular, and strong. Discidium fine, narrow and relatively long, almost straight, and gracile ( Fig. 5F ). Epimeral setae, except 4d, inserted on small, but distinct tubercles. Epimeral setal formula 3-1-4-3; epimeral setae relatively short, with 1b the longest (about 25 µm). Anogenital region with normal setation, with 6g, 1ag, 3ad and 2 an present. One of the anal plates with additional smaller seta posteriorly. Anal and adanal setae longer than other ventral setae (over 40 µm) with genital setae only slightly shorter. No postanal sclerite observed.

Legs ( Fig. 7 ) — All leg segments with quite distinct bulbs and with fine setation. Only leg IV longer than body (about 1,1 times), other legs shorter (leg I about 0,85 of body length). Femur IV slightly shorter than, or sub-equal in length as trochanter IV; genua I-IV shorter than respective tibiae. Porose areas on all femora and trochanters III-IV well visible. Setae generally smooth, only on ventral side of tibiae and tarsi with short barbs unilaterally. Dorsal setae of femur II and III of unusual shape, stronger, bent, pectiniform with 3-4 distinct barbs dorsally, proximal being the longest in the row. Setal formula of legs (famulus included, solenidia in parenthesis): leg I 1-7-4(1)-4(2)-20(2), leg II 1-6-4(1)-4(1)-17(2), leg III 2-4-3(1)-3(1)-17, leg IV 1-4-3-3(1)-14. Famulus normal, setiform and quite long. Seta ft", famulus and solenidia ω1 and ω2 close together, of similar length, only ω1 slightly longer, curved distally. Tibial solenidia of leg I (’1, about 145 µm) and IV (’, 105 µm) long, setiform, and tactile. Genual solenidia I-III always longer than coupled seta d, and bent distally. Tarsi I and IV with only 2 posterior accessory setae, with v2´absent.

Remarks — The individual stands very near to Epidamaeus floccosus Behan-Pelletier and Norton, 1985 , having very similar or identical development of tubercles and ridges in the sejugal area; parastigmatic apophyses or ventral tubercles are generally of very similar appearance as well. Still, there are also several characters which clearly differ. The british individual is larger; sensillus is shorter, without flagellate end and not covered distally by cerotegument as in E. floccosus . Notogastral setae (particularly l and h series) are inserted on tubercles or short ridges; anterior notogastral setae are finer and longer and, conversely, setae ps1-ps3 are much shorter than in E. floccosus . Ventral setae of our individual are shorter and most of the epimeral setae are inserted on tubercles. Legs differ slightly, also, in having finer and generally shorter setae, and all genual solenidia are longer than the coupled setae d (whilst in E. floccosus , coupled setae are longer than solenidia). Presence of teeth on spinae adnatae on our individual may be an easily observable difference, but it is difficult to judge if this character is stable. Similarly developed spinae adnatae have been observed on some individuals of E. aborigensis Behan-Pelletier and Norton, 1985 , together with individuals where they had developed normally, without teeth or protuberances. As stated above, if the differences found will be proved stable by study of broader material, they justify in our view a status of new species to be proposed. As our attempts to find more individuals were not successful, we brought detailed description here to allow for comparison, and hopefully also for finding of more individuals by other authors, who may have collected the species without attempting detailed determination. Authors will be greatly appreciating if such a material, if exists, was provided them for further study.

Figures

FIGURE 4: Epidamaeus sp. (aff. floccosus Behan-Pelletier and Norton, 1985): A – dorsal view, legs only partly depicted; B – ventral view, legs and gnathosoma only partly depicted (scale bar = 200 µm).

FIGURE 5: Epidamaeus sp.(aff. floccosus Behan-Pelletier and Norton, 1985): A – lateral view of rostrum, B – lateral view on bothridial area and anterior part of notogaster, C – genital setae g1-g5, aggenital seta and adanal seta ad3; D – lateral part of prodorsum; E – parabothridial apophyses Sa and Sp; F – discidium; G – spinae adnatae (scale bars = 25 µm).

FIGURE 6: Epidamaeus sp. (aff. floccosus Behan-Pelletier and Norton, 1985): A – sensillus and bothridial area; B – interbothridial seta;

FIGURE 7: Epidamaeus sp. (aff. floccosus Behan-Pelletier and Norton, 1985): A – femur and genu I; B – genu, tibia and tarsus I; C – femur, genu and tibia II; D – trochanter, femur and genu III; E – trochanter, femur and genu IV; F – genu, tibia and tarsus IV (scale bar = 50 µm).