Mašán, Peter ¹ and Halliday, Bruce ²

¹✉ Institute of Zoology, Slovak Academy of Sciences, Dúbravská cesta 9, 845 06 Bratislava, Slovakia.
²Australian National Insect Collection, CSIRO, GPO Box 1700, Canberra ACT 2601, Australia.

2024 - Volume: 64 Issue: 3 pages: 697-710

ZooBank LSID: A95A6FFF-D3A4-4683-B3C8-AA5EE32240CA

Original research

Keywords

Abstract

Introduction

Mites in the cosmopolitan mite family Laelapidae include free-living predatory species as well as parasites and commensals of arthropods and vertebrates. Some species are considered ectoparasites of medical or veterinary importance, and are capable of causing dermatitis in humans and transmitting pathogens such as tularemia, plague, murine typhus, rickettsial pox and arthropod-borne viral encephalitis (Mullen and OConnor 2002).

The taxonomic concepts of the family Laelapidae have changed considerably over the last century. Evans and Till (1966) provided the first detailed historical overview of the classification of the subfamily Laelapidae. An important recent contribution to the understanding of the family was made by Moraes et al. (2022). The number of free-living and arthropod-associated laelapid taxa considered valid in their world catalogue is 1,088 species in 73 genera (and 52 genera for vertebrate-associated species). The family has been estimated to include more than 1,300 species classified in 90 genera (Beaulieu et al. 2011) or 1,520 species in 146 genera (Keum et al. 2017). These large discrepancies reflect the instability of the internal classification, which is complicated by the apparent non-monophyletic origin of the taxa considered, diverse adaptations to parasitism, and the uncertain morphological definition of the family and many of its genera (Moraes et al. 2022).

The aim of this study is to describe a new species and genus of laelapid mite from Slovakia and thus contribute to the knowledge of the fauna of Mesostigmata in Europe. This work is part of a project that aims to expand our knowledge of the mite fauna associated with arboricolous microhabitats.

Material and methods

Mites were collected from under loose tree bark with a wet toothpick and preserved in ethyl alcohol, then mounted on microscope slides with Swan's chloral hydrate mounting medium. Measurements and photographs were taken from slide-mounted specimens using a Leica DM 1000 light microscope and a Leica EC3 digital camera. The length of shields and legs was measured along their midline, the width at their widest point, unless otherwise stated in the description. Dorsal setae were measured from the base of their insertions to their tips, legs I–IV with the coxa but without the pretarsal ambulacrum. The measurements are given as ranges (minimum to maximum). The terminology of dorsal and ventral chaetotaxy follows Lindquist and Evans (1965) and the setal nomenclature used for the legs is that of Evans (1963). The notation for the pore-like structures of the idiosoma in this study generally follows Athias-Henriot (1969), Krantz and Redmond (1987) and Johnston and Moraza (1991).

Results

Ochaechulla gen. nov.

ZOOBANK: BA3C8F2F-1F29-4BC2-AFC9-BF50F1C172B0

(Figures 1–5)

Type species

Ochaechulla spinturniciformis sp. nov.

Diagnosis (Female)

Idiosoma obovate, all legs thick and short, shorter than dorsal shield. Dorsal shield obovate, not covering entire dorsal surface, with 36 pairs of setae, 21 pairs podonotal (j1–j6, z2–z6, s1–s6, and r2, r3, r5, r6) and 15 pairs opisthonotal (J2–J5, Z1–Z5, S1–S5, and R1); setae z1, r4 and J1 absent; posterior dorsomarginal setae (except R1) located on soft integument next to the lateral margins of the shield. Idiosomal setae smooth, mostly basally thickened, their tips extending beyond the bases of following setae; vertical setae (j1) thinnest and shortest; humeral setae (r3) similar in length to adjacent setae; Z5 elongate. Dorsal and ventral shields finely punctate on surface, without reticulation or specific ornamentation, except for a transverse row of denticles anterior to bases of setae Z5 and J5. Tritosternum small, with short base and thin and finely pilose laciniae. Separate presternal platelets absent. Sternal and epigynal shields large, together occupying more than 3/4 of the total length of the idiosoma. Sternal shield about as wide as long, subquadrate, without lateral corners between setae st2 and st3; separate endopodal platelets between coxae II–III absent. Metasternal setae (st4) and associated lyrifissures (iv3) absent. Epigynal shield anteriorly with well-developed and broadly convex hyaline part, reaching beyond posterior margin of sternal shield. Peritremes strongly reduced to a very short prestigmatic section. Peritrematal shields small, suboval, located dorsolaterally in shallow indentation of the dorsal shield between setae r3 and r5. Anal shield subcircular, with posteriormost part reaching dorsal surface; postanal seta (pa) conspicuously long. Gnathosomal corniculi horn-like, well separated and sclerotized; ventral surface of hypostome with seven or eight transverse rows of denticles. Anterior margin of epistome convex and finely denticulate. Palp tarsus with two-tined claw. Cheliceral digits short, chelate-dentate, with straight or only weakly curved terminal hooks; movable digit with a strong submedial tooth. Many leg segments with reduced number of setae; trochanters I–IV with five setae each; femora I–IV with 12, 9, 6, 6 setae; genua I–IV with 12, 10, 8, 9 setae; tibiae I–IV with 10, 8, 7, 9 setae; and tarsi II–IV with 16, 16, 14 setae.

Etymology

The generic name is derived from a character in Slovakian folklore (feminine).

Ochaechulla spinturniciformis sp. nov.

ZOOBANK: 9D6EB8B5-D606-4A46-AF17-10281053E0DE

(Figures 1–5)

Type material

Holotype female: NW Slovakia, Javorníky Mountains, Považská Bystrica district, road between the settlement of Orlové and the village of Uhry (49°08′36.26″ N, 18°25′14.48″ E), next to the Nosice reservoir, under the loose bark of an old beech trunk (Fagus sylvatica) with peeling bark, elev. 285 m, 15 Sept. 2023, coll. P. Mašán. Paratype: female, with the same data as the holotype. Specimens are deposited at the Institute of Zoology of the Slovak Academy of Sciences, Bratislava, Slovakia.

Description (Female)

Female. Dorsal idiosoma — (Figures 1A, 3). Idiosoma 410–425 μm long, 280–295 μm wide, dorso-ventrally flattened, ovoid, almost completely covered by dorsal shield, except for narrow lateral and posterior parts. Dorsal shield 380–395 μm long, 250–265 μm wide, widest at level of r5, ovate to subpentagonal, regularly convex anteriorly, moderately curved to almost straight posteriorly, with well-formed and rounded posterolateral corners; lateral margins with small shallow indentations between setae r3 and r5 and between S2 and S4; surface finely and densely punctate, without reticulation or pattern of lines, except for a transverse row of denticles located along bases of J5 and Z5 near posterior margin of the shield. Dorsal shield with 36 pairs of setae, 21 podonotal (j1–j6, z2–z6, s1–s6, r2, r3, r5, r6) and 15 opisthonotal (J2–J5, Z1–Z5, S1–S5, R1); z1, r4 and J1 absent. Setae smooth, mostly conspicuously thickened basally, up to 6 μm at widest point; opisthonotal setae with tips reaching clearly beyond the base of the following seta. Posteromarginal soft integument with three pairs of R and two pairs of UR setae. Dorsal shield setae mostly similar in size and form, spine-like, j1 shortest (14–16 μm), Z5 longest (103–118 μm); marginal and submarginal setae on posterior soft integument shorter and thinner than those on dorsal shield. Lengths of dorsal setae: j2 33–38 μm, j3 and j4 40–47 μm, j5 50–57 μm, j6 54–62 μm, J2 54–60 μm, J3 52–58 μm, J4 44–50 μm, J5 42–48 μm, z2 and z3 39–45 μm, z4 46–52 μm, z5 and z6 50–56, Z1 and Z2 51–58 μm, Z3 41–50 μm, Z4 37–44 μm, s1 36–44 μm, s2 36–40 μm, s3 42–48 μm, s4 48–55 μm, s5 36–42 μm, s6 46–52 μm, S1–S3 43–49 μm, S4 41–47 μm, S5 41–45 μm, r2 35–40 μm, r3 37–45 μm, r5 38–42 μm, r6 34–38 μm, R1 31–35 μm, other R-setae 26–31 μm, and UR-setae 24–28 μm.

Ventral idiosoma — (Figures 1B, 4A). Tritosternum small, with short and broad base (12 x 13 μm) and two finely pilose laciniae; laciniae free, thin and 36–39 μm long (Figures 5C, 5D). Presternal area without separate platelets. Sternal shield large, almost as long as wide, 155–160 μm long and 150–157 μm wide at widest point at level of iv2, 125–130 μm wide at narrowest point between coxae II, 135–140 μm wide at level of st2; medial anterior margin with slight indentation near tritosternum, posterior margin straight and irregularly undulate; lateral corners between coxae II and III inconspicuous, rounded; shield with two pairs of slit-like lyrifissures (iv1, iv2) and three pairs of similar needle-like setae (st1 33–38 μm, st2 29–33 μm, st3 30–36 μm). Metasternal setae (st4), platelets and lyrifissures (iv3) absent. Endopodal platelets II–III absent, those between coxae III and IV small and narrow. Epigynal shield large and elongate, 160–180 μm long, 110–115 μm wide at widest anterior part, 65–70 μm at narrowest medial part and 90–100 μm at widest posterior part, moderately constricted at level of coxae IV, almost flask-shaped, hyaline and widely convex anteriorly, hyaline margin reaching the level of st3, widely curved to almost straight posteriorly, with a pair of needle-like setae slightly shorter than sternal setae (st5 19–24 μm); genital lyrifissures (iv5) located on soft integument behind genital setae. Sternal and epigynal shields relatively large in relation to the body, together occupying more than 3/4 of the total length of the idiosoma. Anal shield small, 48–53 μm long from anterior margin to post-anal seta, 66–72 μm wide, subcircular, with small medial protuberance on anterior margin and three circumanal setae; post-anal seta at least twice as long as adanal setae (pa 70–75 μm, ad 26–36 μm); anus small, 14–15 μm long and 9–10 μm wide, centrally located on shield; cribrum with at least larger part placed dorsally; gland pores gv3 small and placed on lateral margin of shield, at level of anterior margin of anus. All ventral shields finely punctate on surface, without reticulation or specific ornamentation. Peritrematal structures dorsal to dorsolateral; peritremes 40–45 μm long, reduced to stigma and a very short prestigmatic part almost as long as stigma; separate fragment of peritrematal shields (27–31 μm long) present in slight anteromarginal incision of dorsal shield between setae r3 and r5, bearing two pore-like structures, lyrifissure id3 placed in the middle of medial margin, and gland pore gp3 adjacent to posterior margin and less obvious than id3 (Fig. 3). Exopodal plates absent except for a pair of very small subtriangular platelets between coxae II and III. Parapodal plates behind coxae IV narrow, ending near stigma. Opisthosomal integument with a pair of very small suboval to subcircular (7–8 μm) metapodal platelets behind coxae IV. Soft lateral and opisthogastric integument with six pairs of setae (JV1, JV2, JV4, JV5, ZV2, ZV5), of which three pairs (JV1, JV2, ZV2) thickened and similar in shape to those on dorsal shield; lengths of opisthogastric setae are as follows: JV1 36–44 μm, JV2 39–48 μm, JV4 34–42 μm, JV5 55–65 μm, ZV2 37–42 μm, and ZV5 24–31 μm.

Sperm induction system — Posterior margin of coxae III with a thin sperm induction tube sclerotized only in its short, proximal part (Figure 5B). Other components of sperm system not visible, apparently unsclerotized.

Gnathosoma — Anterior margin of epistome convex and densely denticulate, roof-shaped, with moderate median angle (Figures 4B, 4C). Venter of hypostome with wide longitudinal furrow bearing seven or eight transverse rows of denticles connected laterally by longitudinal lines, each row with up to ten denticles; corniculi well sclerotized and widely spaced, horn-like, slightly convergent, distinctly shorter than internal malae or labrum (Figures 5C, 5D); salivary stylets setiform, nearly as long as internal malae. Hypostomal setae smooth and thick, needle-like to spine-like; setae h3 thickest, h2 shortest and thinnest (h1 and pc 25–30 μm, h2 16–21 μm, and h3 35–42 μm). Median article of chelicerae 60–70 μm long, with chelate-dentate digits rather short and broad; fixed digit with three small teeth and bi- or tridentate terminal tip; movable digit with a strong distal tooth and a straight to weakly curved terminal hook; pilus dentilis small and setiform, not modified into an inflated and robust seta; dorsal seta indistinct, not observable (Figure 4D); arthrodial membrane at base of movable digit without a simple corona of short filaments. Palp trochanter with two ventral setae; femur with five setae (1-3/0-1); genu with six setae (2-3/0-1), of which two anterolateral setae simple, short, and slightly thickened basally but pointed distally; tibia and tarsus with 14 and 15 setae respectively; palp tarsal claw two-tined.

Legs — (Figures 2, 5A). All legs rather thick, shorter than idiosoma, and with well-developed pretarsus and ambulacral apparatus including pulvillus and two claws; claws of pretarsi I similar in size to those of pretarsi II–IV; tarsi II–IV each with subtriangular ventroapical process; coxae rather large, those of legs II and III projecting beyond lateral margins of idiosoma and dorsally exposed, mostly visible in dorsal view; and arranged almost radially on anterior 3/4 of idiosoma; legs I longest and legs II shortest: legs I 320–335 μm, legs II 270–280 μm, legs III 275–290 μm, legs IV 310–325 μm long. Leg chaetotaxy: leg I – coxa (2), trochanter 1-1/2-1 (5; relative to holotrichous laelapids av absent), femur 2-3/1, 2/2-2 (12; pv2 absent), genu 2-3/1, 3/1-2 (12; av2 absent), tibia 2-2/1, 2/1-2 (10; ad3, pd3 and av2 absent); leg II – coxa (2), trochanter 1-0/3-1 (5), femur 1-2/1, 2/2-1 (9; al2 and ad3 absent), genu 2-3/1, 2/0-2 (10; pv absent), tibia 2-1/1, 2/1-1 (8; ad2 and pl2 absent); leg III – coxa (2), trochanter 1-1/3-0 (5), femur 1-2/1, 1/0-1 (6), genu 2-2/1, 2/0-1 (8; pv absent), tibia 1-1/1, 2/1-1 (7; al2 absent); leg IV – coxa (1), trochanter 1-1/3-0 (5), femur 1-2/1, 1/0-1 (6), genu 2-2/1, 3/0-1 (9), tibia 1-1/1, 3/1-2 (9; al2 absent); telotarsi II–IV with 12 setae (ad1 and pd1 absent), basitarsus IV with only two dorsal setae, ad3 and pd3 (al3 and pl3 absent). Leg setae smooth and mostly needle-like; some dorsal setae on some leg segments slightly attenuated and elongated distally – pd1 on femur II, ad1 on genua III and IV and on femora III and IV, and ad3 on tarsus IV.

Etymology

The specific name is derived from the words ''Spinturnix'' (genus of gamasine mites) and Latin ''forma'' (appearance) and refers to the fact that the new mite resembles those of Spinturnix von Heyden in terms of the unusual position and arrangement of the leg coxae on the idiosoma.

Discussion

Ecological notes

It is difficult to specify the habitat preference and trophic requirements of the new species. The specimens were found under tree bark and their body shows pronounced dorso-ventral flattening, which is typical for species that occur in spatially flat subcortical microhabitats, but we do not assume that ecological specialization for this species. Flattened subcortical species are found in families such as the Digamasellidae (Dendrolaelaps-like species), the Melicharidae (Proctolaelaps spp.) and the Blattisociidae (Lasioseius spp.). However species of Laelapidae, including Hypoaspis-like species, are rarely flattened and specially adapted to life in bark habitats. An exceptional example is Hypoaspisella pini (Hirschmann et al. 1969), which lives in the galleries of bark beetles of the subfamily Scolytinae, and some species that are specifically associated with decomposing wood substrates and are phoretic on saproxylic beetles in the families Lucanidae and Scarabaeidae (Moraes et al. 2022).

It is possible that Ochaechulla spinturniciformis is bat-associated rather than a free-living subcortical or saproxylic detriticole, for the following reasons: (1) the senior author has been observing and collecting the subcortical mesostigmatic mite fauna in Slovakia for many years and has not found any similar species so far; (2) the tree bark where the types were collected was loose at its edge, which creates a suitable place for bats to roost and hide [similar microhabitats were reported, for example, by Zahn and Hammer (2017), Dietz et al. (2018) and Apoznański et al. (2021)], and even the narrowest space between bark and cambium was relatively dry, as required for the occurrence of the common fauna of subcortical mites and wood-destroying insects; (3) the type locality is in close proximity to an extensive area of water with significant nocturnal flight activity of foraging bats; and (4) the external dorsal habitus of the species resembles ectoparasitic species from the genus Laelaps C. L. Koch, much more than free-living edaphic Hypoaspis-like species (or some strictly subcortical Dendrolaelaps-like species), although morphological features of the chelicerae in the new species do not clearly indicate a parasitic mode of life and active hematophagy.

Taxonomic notes

The most comprehensive monograph on mites associated with bats (Radovsky 1967) contains only two genera and three species of Laelapidae found exclusively on bats in the Oriental and Australian regions, namely Neolaelaps Hirst, 1926 and Notolaelaps Womersley, 1957 (see also Shaw, 2011). These genera are easily distinguished from the new genus by the presence of setae st4 on the metasternal surface and three pairs of setae on the epigynal shield, and by well-developed peritremes connected dorsolaterally to the anterior part of the dorsal shield. The presence of accessory setae on the epigynal shield is also common in other laelapid genera of ectoparasites associated with vertebrates (e.g. Hyperlaelaps Zachvatkin, Laelaps, Mysolaelaps Fonseca, Tur Baker & Wharton, among others). Heath et al. (1987) described another genus based on specimens from bats in New Zealand, namely Chirolaelaps. In contrast to the newly described genus, Chirolaelaps also has well-developed peritremes and metasternal setae, in addition to edentate chelicera, paravertical setae, holotrichy of the legs, and 21 pairs of setae on the soft posterior integument.

The Laelapidae is such a large and diverse assemblage of free-living and parasitic genera with such morphological and behavioural heterogeneity that it cannot be readily defined by a single or specific combination of apomorphic characters. From our observations on Ochaechulla, and from comparison with other laelapid genera and species, we conclude that the size and arrangement of coxae I‒IV on the body is unusual and could be considered an important apomorphic feature for this genus. On the one hand, the coxae are very large, with coxae III as large as coxae II, and arranged almost radially on the anterior 3/4 of the idiosoma, not on the anterior 1/2 or 2/3 of the idiosoma as in other members of the family, so that the idiosoma projects only slightly more behind coxae IV than in front of coxae II. On the other hand, the position of the coxae is extremely close to the lateral margins of the idiosoma. As a result of this position, coxae II and III in particular are not completely covered by the idiosoma, but protrude beyond its lateral margins and are clearly visible in dorsal view (Figures 2, 5A). In general, the podonotal part of the dorsal shield occupies proportionally more area along the longitudinal axis than the opisthonotal part, which is more prominent on the ventral side, as the sternal and genital shields occupy 2/3 of the length of the idiosoma. A similar, almost radial arrangement of the strong legs, but with a normal ventral position of the coxae, is only found in one other laelapid genus, namely Tympanospinctus Berlese, 1918 (= Mungosicola Radford, 1942), whose members live in Africa in association with mongooses (Carnivora). In his original description, Berlese (1918) stated that Tympanospictus was closely related to Spinturnix.

Another apomorphy of Ochaechulla is the deficient setation of basitarsus IV, which has only two dorsal setae (ad3 and pd3) and lacks two lateral setae (al3 and pl3). According to Evans (1963), the chaetotaxy of tarsi II‒IV is very constant in all free-living Gamasina, although in obligate dermanyssoid parasites there is a tendency to reduce the size of the apicodorsal setae (ad1 and pd1), which may be represented by microsetae or absent (Evans and Till 1965; Uppstrom and Klompen 2005). We also observed the absence of apicodorsal setae in the new genus. The chaetotactic pattern for basitarsi II‒IV appears very constant in Mesostigmata, including laelapid mites (Evans 1963, Evans and Till 1966, Moraes et al. 2022). The specific absence of lateral setae on basitarsus IV has not previously been found in the Laelapidae and is rarely developed in other taxa of Gamasina, for example in species of the digamasellid genus Longoseius Chant, which may additionally lack a dorsal seta on the same segment (Lindquist 1975), and in some species of Rhodacaridae and Ologamasidae (Lee 1970).

Further important diagnostic characters that separate Ochaechulla from other laelapid genera are: (1) the dorsal shield setae are thick and reduced in number, lacking setae z1, r4, J1, Zx2, Zx3, and Jx; (2) the peritrematal structures are greatly reduced to a small free platelet separate from the dorsal shield and distant from the peritreme, and a very short peritreme, almost as short as the stigma, both located dorsally; (3) metasternal setae and associated lyrifissures are absent; (4) sternal and epigynal shields are enlarged, occupying more than 3/4 of the length of the idiosoma; (5) the opisthogastric region is hypotrichous; and (6) most leg segments are hypotrichous.

Moraes et al. (2022) listed the following combination of features that reliably serve to distinguish most laelapids from other families of Mesostigmata: (1) holodorsal shield, especially when bearing Zx2, Zx3, or Jx setae; (2) usually tongue-shaped epigynal shield, often widened posteriorly; (3) small subtriangular or pear-shaped anal shield; (4) setae st4 on non-sclerotized cuticle; (5) narrow and posteriorly free peritrematal shield; (6) convex epistome; (7) six rows of deutosternal denticles; (8) bidentate movable digit of chelicerae; and (9) femur, genu and tibia of leg I with 13 setae each. With some exceptions, most of these features characteristic of most Laelapidae are different in Ochaechulla. It lacks accessory setae Zx2–3 and Jx on the dorsal shield and setae st4 in the metasternal region, the poststigmatic part of the peritrematal shield is absent, the deutosternum has seven or eight rows of denticles instead of the usual six, and the movable digit of the chelicerae is not bidentate but unidentate. In addition, in most laelapids setae Z5 are usually located inserted more posteriorly than laterally to J5.

However, as the new genus has some features that are also found in the other superfamilies, we classify it as a laelapid genus of Dermanyssoidea for the following reasons: (1) a single dorsal shield; (2) the sternal shield is well developed and entire, with setae st1–3 and lyrifissures iv1–2; (3) the absence of metasternal setae which are normally present in non-dermanyssoid taxa; (4) the epigynal shield extends posteriorly well beyond the posterior margin of coxae IV; (5) the anal shield is small compared to the sternal and epigynal shields, free and has only three circumanal setae; (6) chelate-dentate digits of the chelicerae; (7) convex epistome with denticulated anteromedial margin; (8) sperm induction structures associated with coxae III; and (9) absence of the phytoseioid type of sperm system characteristic of a usually well-sclerotized calyx-shaped structure between coxae III and IV.

The convex epistome was used as one of the features to justify our placement of the new genus in the Laelapidae. However, it must be admitted that the anterior margin of this structure is not regular or perfectly convex and that, while the middle third is normal, the sides are rather straight (diagonal) and somewhat separated from the medial part by small notches, as if it was tripartite, as in some species of the melicharid genus Proctolaelaps Berlese. The tectum thus does not clearly indicate a relationship with the laelapids, although the shape of the tectum varies greatly within the family and a slightly tripartite shape of the epistome is also found in other species, namely Cosmolaelaps cuneifer (Michael) and Hypoaspisella lubrica (Oudemans & Voigts) (see Evans and Till 1966).

Also the shape of the epigynal shield in Ochaechulla is not typical for a species of Laelapidae. The epigynal shield is often widened behind st5 in Laelapidae, but in those cases its posterior margin is smoothly rounded, semicircular or ovoid. Ochaechulla is unusual in showing a visible inflexion between the lateral and posterior margins of the shield, with narrowly rounded posterolateral corners, and a convex posterior margin similar to that found in some Melicharidae.

The presence of a basal paraxial projection of the corniculus is another unusual feature for Laelapidae, but is typically well developed in Melicharidae (Lindquist, personal observation). However, the Melicharidae are primarily characterized by apomorphic cheliceral features that are not found in the new genus: the pilus dentilis is expanded into a hyaline flap (setiform in the latter), and the movable digit generally has a pointed structure (mucro) on the median ventral surface (no remnant of this is present in Ochaechulla; Moraza and Lindquist 2011).

Laelapidae typically bear 39 pairs of setae, including Zx2–3 (sometimes absent), and commonly 1–5 unpaired Jx setae (sometimes more), but in moderately to strongly hypotrichous species, setae Zx2–3 are usually and Jx are almost always absent. The setation of the leg segments in Ochaechulla also differs from most laelapid genera, as presented by Moraes et al. (2022) (their figures in parentheses): trochanter I with five (six) setae, of which two (three) ventrals; femur I with 12 (13) setae, of which three (four) ventrals; genu I with 12 (13) setae, of which two (three) ventrals; tibia I with 10 (13) setae, of which two (three) ventrals and four (six) dorsals; genu III with eight (nine) setae, of which one (two) ventral; tibia III with seven (eight) setae, of which one (two) anterolateral; tibia IV with nine (ten) setae, of which one (two) anterolateral; telotarsi II‒IV with 12 (14) setae, of which five (seven) dorsals; and basitarsus IV with two (four) setae, of which none (two) lateral.

Compared with the normal laelapid pattern of leg chaetotaxy found in most species living freely in soil or in vertebrate nests (Moraes et al. 2022; Beaulieu, personal observations) or in ectoparasites associated with vertebrates (Evans and Till 1966), the new genus can be characterized by hypotrichy, which is widely distributed in taxa associated with arthropods (Moraes et al. 2022). In the genus Ochaechulla there are the following setal deficiencies:

1. trochanter I has only five setae as in Dyscinetonyssus Moss & Funk, Urozercon Berlese, many Myrmozercon Berlese and some species of Dicrocheles Krantz & Khot and rarely Gaeolaelaps Evans & Till;
2. femur I has 12 setae, lacking one posteroventral seta, which is found in at least some species of several genera (Berlesia Canestrini, Dicrocheles, Dyscinetonyssus, Gaeolaelaps, Gecarcinolaelaps Casanueva & Johnston, Julolaelaps Berlese, Laelaspisella Marais & Loots, Ljunghia Oudemans, and Scissuralaelaps Womersley);
3. femur II has nine setae (lacking one ad and one al) in Conolaelaps Womersley, Katydiseius Fain & Lukoschus, and rarely Gaeolaelaps, Myrmozercon, and Reticulolaelaps Costa;
4. genu I has fewer than the normal 13 setae in several other laelapid genera and bears 12 setae (lacking one ad or one av) in some Berlesia, Julolaelaps, Ljunghia, and Scissuralaelaps;
5. genu II bears ten setae (without pv), which is not observed in other laelapid genera such as Gecarcinolaelaps, Julolaelaps, Ljunghia, Narceolaelaps Kethley, Myrmozercon, and Urozercon, which have the same number of setae on genu II, but usually without ad, al, pl or ad3;
6. genu III has eight setae (pv absent) also in Alphalaelaps Radford, Hyperlaelaps, Ondatralaelaps Evans & Till, and Reticulolaelaps, rarely Gaeolaelaps and Julolaelaps;
7. tibia I with identical chaetotaxy, without av2, ad3, pd3 (2–2/1, 2/1–2) as in Dyscinetonyssus and some Myrmozercon, although there are some species in other genera with ten setae (Berlesia and Julolaelaps);
8. tibia II with eight setae (without ad2 and pl2) is also developed in Dyscinetonyssus and one species of Ljunghia, but fewer setae than normal (10) also occur in Gecarcinolaelaps, Narceolaelaps, and some Myrmozercon (lacking one ad), and in most Julolaelaps, Ljunghia, and Urozercon (lacking one pl);
9. tibia III has seven setae (1–1/1, 2/1–1; with al1 and pl1), retaining the larval setal complement and only one anterolateral seta, as in Conolaelaps, Dicrocheles, Iphiolaelaps Womersley, Katydiseius, Melittiphisoides Delfinado-Baker, Baker & Flechtmann, Scorpionyssus Fain & Rack, some Myrmozercon, and rarely Hyperlaelaps, Julolaelaps, and Ljunghia;
10. tibia IV bears nine setae, lacking one anterolateral seta (al2), as in Gecarcinolaelaps, but nine setae are also present in Narceolaelaps and some Gaeolaelaps, Julolaelaps, Ljunghia, and Myrmozercon (but without pd or pl);
11. telotarsi II‒IV with only 12 setae, without dorsoapical processes (ad1 and pd1), as only in Melittiphis Berlese;
12. basitarsus IV without one anterolateral and one posterolateral seta (al3 and pl3; with only ad3 and pd3), so far not found in Laelapidae.

Acknowledgements

We thank Frédéric Beaulieu (Canadian National Collection of Insects, Agriculture and AgriFood Canada, Ottawa, Canada) for his helpful comments during the review of our manuscript. This work for the first author was fully supported by the Scientific Grant Agency of the Ministry of Education of the Slovak Republic and the Academy of Sciences [VEGA Grant No. 2/0007/22: Mesostigmatic mites associated with subcorticolous habitats and wood-destroying insects in Slovakia ‒ taxonomy, ecology and chorology of the species of Digamasellidae (Acari: Parasitiformes)].

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