Amiracarus Miko, 2013

Miko, Ladislav, Mourek, Jan, Meleg, Ioana N. & Moldovan, Oana T., 2013, Oribatid mite fossils from pre-Quaternary sediments in Slovenian caves II. Amiracarus pliocennatus n. gen., n. sp. (Microzetidae) from Pliocene, with comments on the other species of the genus, Zootaxa 3670 (4), pp. 557-578 : 562-566

Diagnosis of Amiracarus Miko , n. gen.

Diagnosis. Microzetidae of small to medium size (295–350 µm, usually close to or above 300 µm), with broad notogaster and shorter prodorsum (ratio prodorsum length:notogater length always above 1:2, ranging from 1:2,2 to 1:4,5; see Fig. 5 A ), usually largely covered by lamellae in dorsal view except for interlamellar area. Lamellar cusps axially parallel, subparallel or diverging anteriad, usually with two distal teeth, although abaxial tooth may be reduced. Incision between teeth shallow or absent, lamellar seta may be inserted closer to abaxial tooth, or about in the middle of distance between both lamellar teeth, positioned apically or—usually in case when abaxial teeth are absent or only slightly indicated—on the surface of lamellar cusp, far from its margins. Tutorium complex, consisting of three tutorial carinae ( Figs 2 D , 5 B , 8 F–G ). Usually, tutorial carinae 1 and 2 developed as straight or slightly bent ribs, converging anteriad and ending with single, more or less distinct, sharp tutorial cusp (tooth). Tutorial carina 3 shorter, but also well developed and ending similarly by sharp cusp. Whole tutorial complex therefore with two tutorial cusps distally, bases of free tutorial cusps usually connected with another carina or line. Interlamellar seta inserted on the lamella. Notogaster anteriorly with distinct or indistinct dorsosejugal line, lateral margins of notogaster not or hardly narrowing anteriad. Pteromorph developed as relatively narrow and prolonged, rounded blade without angular tip distally ( Fig. 5 A–B ). Notogastral setae e 2 and f 2 mostly shifted backwards, e 2 usually on the level of half of the notogastral length or more posteriad. Seta h 3 in normal position medio- or posterolaterally, usually in the vicinity of notogastral lateromedial furrow, close to lateral edge of notogaster. Camerostome prolonged and slightly narrowed anteriad, of piriform appearance ( Fig. 3 D ), with rostral incision anteriorly, usually well visible in ventral view. Rutellum (usually) specifically modified, forming rutellar microtube. Epimeral seta 4c inserted on ventral surface of discidium.

Type species: Miracarus senensis Bernini 1975

Other known species: A. discrepans ( Mahunka 1966) n. comb., A. similis (Subìas & Iturrondobeitia 1977) n. comb., A. abeloosi ( Lions 1978) n. comb., A. grootaerti ( Wauthy & Ducarme 2011) n. comb.

Derivatio nominis. The proposed name is based on the name of Miracarus Kunst 1959 , extended by prefix A -, and should indicate the relationship of the two taxa.

Remarks. Characters, clearly differentiating the genus Miracarus from the new genus Amiracarus are summarised in Table 1 and demonstrated in Fig. 5 . They include: (a) the proportions of the body in Miracarus the ratio of lengths prodorsum:notogaster is below 1:2, in Amiracarus it is above 1:2 and can even exceed 1:4; (b) notogaster is remarkably wider than prodorsum in Amiracarus , while in Miracarus it is less pronounced; (c) pteromorphs are pointed and triangular in Miracarus , and rounded and more narrow blades in Amiracarus ; (d) tutoria, while being complex in both genera, differ by presence of 2 cusps anteriorly in Amiracarus , contrary to single one in Miracarus ; (e) longitudinal axis of pedotectum I in lateral view is more vertical in Amiracarus and more horizontal in Miracarus , so that the distance between anterior and posterior limit of pedotectum I is much shorter in Amiracarus ; (f) notogastral seta h 3 is shifted anteriomediad in Miracarus creating almost one longitudinal row with setae e 2 and f 2, while in Amiracarus it is positioned close to the notogastral margin and creates more or less one (curved) row with setae h 1 and h 2; (g) notogastral seta e 2 is far more forwards than the midlength of notogaster in Miracarus , while in Amiracarus it may be at about the middle of notogaster length or behind it, more posterior; (h) sensillus of Miracarus has much longer head and shorter stalk, the head is distally sharply lanceolate, in Amiracarus the stalk is relatively longer and the head is more fusiform-lanceolate, less acute distally. Further differences can be seen ventrally: (i) mentum is broader and shorter in Miracarus ; (j) rutella are flat, normally developed in Miracarus while in Amiracarus they are (at least in species where they were studied) modified, forming so called rutellar microtube ( Fig. 3B , see also Wauthy & Ducarme 2011); (k) position of epimeral setae differs slightly, more remarkable is the difference in position of seta 4c, which is directly on discidium in Amiracarus and in a broader area between the discidium and circumpedal line in Miracarus .

TABLE 1.

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As these characters almost invariably occur in all Amiracarus species and differ in Miracarus hurkai , it seems to be clear that they have a supraspecific, i.e. generic, character.

Figures

FIGURE 2. Amiracarus senensis (Bernini 1975) n. comb. (fossil individual from sediments of cave Ponicova, Romania). A—dorsal view; B—ventral view; C—lateral view; D—detail of tutorium; E—sensilus. Legs missing, only trochanters III and IV remained preserved. Bar indicating 100 µm (A, B, C). Abbreviation: ao—anal opening, cgl— circumgastric line, cpl—circumpedal line, dis—discidium, go—genital opening, lam—lamella, mt– mentotectum, pd1— pedotectum I, pd2—pedotectum II, pt—pteromorph, R—acetabular protrusion of leg III, sl—notogastral lateromedial furrow, ss—sensillus, trIV—trochanter IV, tu—tutorium, tu1—tutorial carina 1, tu2—tutorial carina 2, tu3—tutorial carina 3. Rest represents names of setae or setal insertions and lyrifissures.

FIGURE 3. Amiracarus pliocennatus Miko, n. sp. (A–C, E holotype from Trhlovca Cave, Slovenia; D—paratype from Račiška pečina Cave, Slovenia). A—dorsal view; B—ventral view (part); C—lateral view of prodorsum and podosoma; D—ventral view of camerostome and rostrum; E—detail of rostrum, dorsolateral view. Bars indicating 50 µm (A, C), 100 µm (B) and 25 µm (D). Abbreviations: cgl—circumgastric line, cpl—circumpedal line, dis—discidium, inc—rostral incision, lam—lamella, mt—mentotectum, pd1—pedotectum I, pd2—pedotectum II, pt—pteromorph, R—acetabular protrusion of leg III, rc—rostral carina, ru—rutellum, sl—notogastral lateromedial furrow, ss—sensillus, TrIII— trochanter III, Tr IV—trochanter IV, tsI—trochanteral seta I, tsII—trochanteral seta II, tu1—tutorial carina 1, tu2— tutorial carina 2, tu3—tutorial carina 3. Rest represents names of setae or setal insertions and lyrifissures.

FIGURE 5. Main differences between genera Amiracarus Miko n. gen. (A–C) and Miracarus Kunst 1959 (D–F), based on the type species (Amiracarus senensis—left, Miracarus hurkai—right, reconstructed from holotype figure, see Fig. 1). Dorsal view of whole body (A and D): proportion between length of prodorsum and length of notogaster (grey arrows); proportion of width of prodorsum and width of notogaster (black arrows); position of interlamellar setae; form of pteromorphs; position of seta e2—in relation to setae in row c2–cp–e2–f2; position of the seta h3—in relation to the seta in row h –h2–h3. Lateral view of anterior part of the body (B and E): form of pteromorph; development of tutoria and tutorial cusps; size and form of pedotectum I. Development of the sensilus (C and F).

FIGURE 8. Amiracarus pliocennatus Miko, n. gen., n. sp., details of holotype and paratype (individuals under A and C from Plate 1). A—lamellar cuspis of holotype in detail, B—lamellar cuspis of paratype in detail, D—sensillus of holotype, E—sensillus of paratype, C—detail of rostrum, paratype, F—lateral view of prodorsum of holotype, G— lateral view of prodorsum, paratype. Abbreviations: bo—bothridium, ctu1—cuspis of tutorial carina 1, ctu3—cuspis of tutorial carina 3, cus—cuspis of lamella, inc—rostral incision, ku—carina ku on pedotectum I, lam—lamella, pd1— pedotectum I, pt—pteromorph, ss—sensillus, tu1—tutorial carina 1, tu2—tutorial carina 2, tu3—tutorial carina 3. Rest represents names of setae or setal insertions and lyrifissures.