Joharchi, Omid ¹ ; Döker, Ismail ² and Khaustov, Vladimir A. ³

¹✉ Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Semakova Str.10, 625003 Tyumen, Russia.
²Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Semakova Str.10, 625003 Tyumen, Russia & Cukurova University, Agricultural Faculty, Department of Plant Protection, Acarology Laboratory, 01330, Adana, Turkey.
³Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, Semakova Str.10, 625003 Tyumen, Russia.

2023 - Volume: 63 Issue: 1 pages: 275-291

ZooBank LSID: 65F623FC-5ACB-4811-B1F4-0ED0ADB669CD

Original research

Keywords

Abstract

Introduction

The nests of social insects provide a favorable habitat for many symbiotic species, which may be parasitic, mutualistic, phoretic, predatory, or commensal with their hosts. Ants are highly organized social insects that create microhabitats through nest construction (Hölldobler and Wilson 1990). Organisms that live in association with ants (i.e. myrmecophiles) are able to enter and access resources within nests, remaining largely undetected by the ant hosts. Myrmecophily is a very common phenomenon in some genera of Laelapidae, and is distributed in several genera. Holostaspis is a well-known ant-associate genus intermediate between Laelaspis and Myrmozercon which comprises 10 nominal species (Babaeian et al. 2019; Moraes et al. 2022). The most recent taxonomic work on the genus was by Babaeian et al. (2019), who described a new species and redescribed six other species of Holostaspis found in association with ants in Slovakia, and attempted to clarify the concept of the genus and distinguish Holostaspis from some related genera. Before the present study, only four species of Holostaspis had been reported from Russia (Bregetova 1977; Joharchi et al. 2019; Joharchi et al. 2020). The present paper is part of a project that aims to increase the knowledge of the poorly studied fauna of insect-associated species of laelapid mites. Towards this aim, we describe two myrmecophilous mite species of the genus Holostaspis and report on another described species that is new record from Russia. In addition, we provide a key for identification of the species of Holostaspis in Russia.

Material and methods

Host ants were collected using an aspirator from their nest, then placed in vials with 96% ethanol. Thereafter, alcohol sediments from the vials were inspected for detached ant-associated mites. Mites were removed from ant nests by extraction from nest material using Berlese-Tullgren funnels. Specimens were cleared in lactic acid solution and mounted in Hoyer's medium (Walter and Krantz 2009). The line drawings and examinations of the specimens were performed with Zeiss Axio Imager A2 compound microscope equipped with differential interference contrast optical systems, attached to camera AxioCam ICc 5. Most images were captured in stacks (with focal depth manually controlled). Selected images were combined using Helicon Focus 7.6.4 Pro (Helicon Soft Ltd., 2000). Digital drawings were prepared using Adobe Photoshop CS2 software based on the original pencil line drawings. Images and morphological measurements were taken via ZEN 2012 software (version 8.0). Photomicrographs were taken with an AxioCam 506 camera (Carl Zeiss, Germany). Measurements of structures are expressed as ranges (minimum–maximum) in micrometres (μm). The length and width of the dorsal shield were taken from the anterior to the posterior margins along the midline, and at level of r3, respectively. Length and width of the sternal shield were measured at the maximum length and broadest points (at level of endopodal between coxae II and III), respectively. The length of the genital shield was measured along the midline from the anterior margin of the hyaline extension to the posterior margin of the shield, and its width where maximal, posterior to genital setae st5. Leg length was measured from the base of the coxa to the apex of the tarsus (excluding the pre-tarsus). The nomenclature used for the dorsal idiosomal chaetotaxy follows that of Lindquist and Evans (1965), the notations for leg and palp setae follow those of Evans (1963a, b), and other anatomical structures mostly follow Evans and Till (1979). Notations for idiosomal pore-like structures (gland pores and poroids/lyrifissures) and peritrematal shield follow mostly Athias-Henriot (1971, 1975). The notations for pore-like structures on the sternal shield and for the peritrematal shield region also follow modifications and additions by Johnston and Moraza (1991) and Joharchi et al. (2020). The holotype and paratypes are deposited at the Acarological Collection of the Tyumen State University Museum of Zoology, Tyumen, Russia (TUMZ).

Taxonomy

Family Laelapidae Canestrini

Genus Holostaspis Kolenati

Holostaspis Kolenati, 1858: 87.

Type species Holostaspis isotricha Kolenati, 1858, by monotypy.

Diagnosis

The concept of Holostaspis used here is based on that of Babaeian et al. (2019) and Moraes et al. (2022). More information about the synonyms and nomenclatural history of the genus are available in Moraes et al. (2022: 290).

Holostaspis ambigua Babaeian et al., 2019

Holostaspis ambigua Babaeian, Mašán and Halliday, 2019: 306.

Holostaspis ambigua. Moraes et al. 2022: 320.

(Figure 1)

Specimens examined — Three females, Yamalo-Nenets Autonomous Okrug, Purovsky District, Russia, 64°52′21.8″N 77°26′34.5″E, 13 July 2022, A.A. Khaustov coll., in the nest of Formica polyctena Förster (Hymenoptera: Formicidae).

Remarks — Holostaspis ambigua was recently described from Slovakia where it was found in anthill of Lasius flavus (Fabricius) (Hymenoptera: Formicidae) (Babaeian et al. 2019). It is now recorded in Russia for the first time, in the nest of Formica polyctena Förster (Hymenoptera: Formicidae). Our specimens agree very well with the description given by Babaeian et al. 2019. The species may be recognized primarily by the dorsal shield inversely ovoid, regularly tapering from level of r5, bearing 39 pairs of setae, including one unpaired accessory setae between J2–J4 (Figure 1A), dorsal setae mostly short (smooth) and similar in length (Figure 1A), barely reaching more than half the distance of following setae (Figure 1A), setae Z5 and S5 longest, about twice as long as most of other dorsal setae; sternal shield as long as wide, mostly smooth (Figure 1B), anal shield subtriangular, with anterior margin straight and anterolateral angles widely rounded (Figure 1B) and post-anal seta slightly thicker and longer than para-anals (Figure 1B). Peritremes relatively long, anteriorly reaching level of s1 (Figure 1B). Corniculi short and narrow, with a protuberance on lateral margin (Figure 1C); fixed digit of chelicera with a small rounded subdistal bulge, movable digit edentate (Figure 1D).

Holostaspis intermedia Joharchi n. sp.

ZOOBANK: FE7681BE-6AD4-40EF-9FEC-28BC3FA53EA3

(Figures 2–4)

Type material

Holotype, female, Yamalo-Nenets Autonomous Okrug, Nadymsky District, Russia, 65°33′08.1″N 72°14′28.9″E, 16 July 2022, A.A. Khaustov coll., in the nest of Formica exsecta Nylander (Hymenoptera: Formicidae). Paratypes, 15 females, same data as holotype.

Diagnosis (adult female)

Dorsal shield bearing 39 pairs of sparsely barbed setae, including five unpaired supernumerary setae Jx (in all examined specimens, without variation), length of setae markedly increasing from anterior to posterior, podonotal setae mostly short, anteromedial setae (j3–j6) barely reaching more than half the distance of following setae, j1 and j2 longer than other anteromedial setae (j3–j6) (almost reaching bases of following setae), setae r-series slightly longer than other podonotals, most opisthonotal setae long enough to reach base of next setae in series, in posterior third of shield setae longer, with J3–J5, Z3–Z5, S3–S5, Zx and Jx setae 1.5–2 times longer than anterior setae, vertical setae (j1) as long as most of podonotal setae; setae z1 shortest, setae J5 and Z5 similar in length. Sternal shield wider than long, strongly concave posteriorly, notched anteromedially and smooth throughout. Anal shield subtriangular, anterior margin concave and anterolateral angles pointed. Fixed digit of chelicera with bidentate terminal hook associated with short pilus dentilis, movable digit with sharp terminal hook and two subapical denticles.

Description (adult female)

Six specimens measured.

Dorsal idiosoma — (Figures 2A & 3A) — Dorsal shield oval to ovoid, 596–608 long, 350–362 wide, reticulate on marginal and posterior surface (anteromedial region smooth); bearing 39 pairs of pilose setae (with 2–6 min barbs): 22 pairs of podonotal (24–44) and 17 pairs of opisthonotal setae, including two pairs of Zx setae between J and Z setae and five unpaired supernumerary seta Jx between J-series (in all examined specimens, without variation), setae heterogeneous in length: in central area shorter (24–40), r-series setae slightly longer (40–50), setae in posterior third of shield longest (60–78) and z1 shortest (13–17). Dorsal shield with 19 pairs of discernible pore-like structures, including four pairs of gland openings (gd1, gd4, gd8, gd9) and 15 pairs of poroids. Shape, position and relative length and thicknesses of setae shown in Figures 2A & 3A.

Ventral idiosoma — (Figures 2B & 3B) — Tritosternum with paired pilose laciniae (64–67), fused basally (4–6), columniform base 16–20 × 20–24 wide; presternal platelets absent. Sternal shield (length 98–105) narrowest between coxae II (111–114), widest at level of endopodal between coxae II and III (186–90), with strongly concave posterior margin (reaching close to level of iv1) and undulating anterior margin, anterior margin with distinct median notch, shield with three pairs of relatively long and smooth sternal setae (barely reaching base of next posterior setae), [st1 (43–45), st2 (46–49), st3 (50–52), and two pairs of poroids (iv1 and iv2 slit-like, adjacent to setae st1 and between st2 and st3, respectively) (Figures 2B & 3B); surface without reticulate ornamentation, almost smooth, except some irregular longitudinal lines laterally, shield fused anterolaterally to narrow endopodal strip between coxae I and II, and to endopodal between coxae II and III. Metasternal setae st4 (50–52) and metasternal poroids iv3 inserted on soft cuticle posterior to sternal shield; metasternal platelets absent. Endopodal plates II/III completely fused to sternal shield, endopodal plates III/IV elongate, narrow, and curved. Genital shield elongated, rounded posteriorly, protruding at level between setae st5 and Zv1, width (166–170) and length (357–362), anterior hyaline margin curved, reaching close to level of iv1; shield with V-shaped ornamentation, shield bearing smooth genital setae st5 (47–50) on edges (Figures 2B & 3B). Shield flanked by a pair of minute elongate paragenital platelets, paragenital poroids (iv5) located on soft cuticle lateral to shield behind st5. Anal shield subtriangular, subequal in length and width (length 98–104, width 73–100), with anterolateral angles sharply pointed and sculptural lines on anterior portion, a pair of lateral poroids (gv3) on lateral margins; bearing long and thick post-anal seta (38–46), and a pair of smooth para-anal setae (32–36), cribrum with wide band of spicules, limited to region posterior to post-anal seta (Figures 2B & 3B). Soft opisthogastric cuticle surrounding genital and anal shields with one pair of elongated metapodal plates (56–60 long × 5–7 wide) and 17 pairs of setae (Jv1–Jv5, Zv1 – Zv5, R1–R4, UR2–UR3, r6); setae different in length (42–75), arising on small sclerotized platelet; mostly sparsely pilose distally (Figures 2B & 3B). Peritreme long, extending to mid-level of coxa I (near s1), peritrematal shield narrow, expanded anteriorly, free from exopodal shields, each shield bearing five discernible pore-like structures, a lyrifissure ip and a gland pore gp at level of coxa II, two lyrifissures ip and a gland pore gp on poststigmatic section (Figures 2B & 3B); anterior part of shield not fused with dorsal shield.

Gnathosoma — (Figures 2C-E & 3 C-D) — Epistome subtriangular, smooth, with well-rounded apex (Figure 2D), corniculi short and pointed, horn-like; internal malae relatively short, pointed, with tips only slightly exceeding the corniculi, finely fringed; labrum longer and blade-like (Figure 2C), hypostomal and capitular setae smooth, h3 (34–38) < pc (28–31) < h1 (22–25) < h2 (18–21); hypostomal groove with six rows of denticles, all rows connected by lateral margins of groove, each row bearing 6–10 denticles, groove progressively narrowing from anterior to posterior ends (Figure 2C). Chaetotaxy of palps: trochanter 2, femur 5, genu 6, tibia 14, tarsus 15, palp tarsal apotele two-tined; shape, position and relative length of setae shown in Figure 3C. Fixed digit of chelicera with bidentate terminal hook associated with short pilus dentilis, pilus dentilis and dorsal seta short, movable digit with sharp terminal hook and two subapical denticles, arthrodial membrane with a rounded flap and normal filaments (Figures 2E & 3D).

Insemination structures — (Figure 3E) — Laelapid-type sperm access system, tubulus long, wider at the solenostome level of coxa III and entering sacculus. Proximal ends of the tubulus swollen at junction with ramus, leading to irregular sacculus.

Legs — (Figure 4) — Legs II and III short (282–290, 299–310), I and IV longer (380–390, 376–386) (excluding pretarsus). Chaetotaxy normal for free-living Laelapidae: Leg I (Figure 4A): coxa 0–0/1, 0/1–0, trochanter 1–0/1, 1/2–1 (pd thickened, spinelike), femur 2–3/1, 3/3–2, genu 2–3/2, 3/1–2, tibia 2–3/2, 3/1–2. Leg II (Figure 4B): coxa 0–0/1, 0/1–0, trochanter 1–0/1, 0/2–1, femur 2–3/1, 2/2–1 (ad1 slightly thickened, inserted on small tubercle), genu 2–3/1, 2/1–2, tibia 2–2/1, 2/1–2. Leg III (Figure 4C): coxa 0–0/1, 0/1–0, trochanter 1–1/1, 0/2–0, femur 1–2/1, 1/0–1 (ad1 slightly thickened, inserted on small tubercle), genu 2–2/1, 2/1–1, tibia: 2–1/1, 2/1–1. Leg IV (Figure 4D): coxa 0–0/1, 0/0–0, trochanter 1–1/1, 0/2–0, femur 1–2/1, 1/0–1, genu 2–2/1, 3/0–1, tibia 2–1/1, 3/1–2. Tarsi II–IV with 18 setae (3–3/2, 3/2-3 + mv, md). All pretarsi with paired claws, rounded pulvilli, and a long thin stalk.

Male & immature stages

Unknown.

Etymology

The specific name intermedia, from the Latin, meaning ''in between'', refers to the species morphologically intermediate between H. isotricha Kolenati and Holostaspis oophila (Wasmann).

Differential diagnosis

The new species is most resembles H. isotricha and H. oophila (couplet 2 in the identification key to Holostaspis species provided by Babaeian et al. 2019), due to the dorsal shield setae J5 and Z5 similar in length, anterolateral angles of anal shield slightly extended and epistome with well-rounded apex. However, the new species can easily be distinguished from both species by having five unpaired accessory setae between J-series (versus one and two unpaired accessory setae between J-series in H. oophila and H. isotricha, respectively); opisthonotal setae 1.5–2 times as long as podonotal setae (versus podonotal and opisthonotal setae similar in length in H. isotricha and opisthonotal setae 2–3 times as long as podonotal setae in H. oophila); anteromedial setae (j3–j6) almost reaching half of the distance of following setae (versus anteromedial setae (j3–j6) reaching about one-third of the distance of following setae in H. oophila and almost reaching bases of following setae in H. isotricha); vertical setae (j1) and setae of dorsal hexagon (j5, z5, j6) more or less similar in length (versus vertical setae 1.5 times as long as setae of dorsal hexagon in H. oophila); sternal shield with distinct anteromedial notch and strongly concave posteriorly, setae with tips almost reaching bases of following ones (versus in both species sternal shield without anteromedial notch; in H. oophila sternal shield with short setae and shallow posterior concavity); fixed digit of chelicera with bidentate terminal hook associated with short pilus dentilis, movable digit with a sharp terminal hook and two subapical denticles (versus in H. oophila fixed digit of chelicera with two teeth, movable digit with a small rounded subdistal bulge).

Holostaspis macrodactyla Joharchi n. sp.

ZOOBANK: 187C83CD-1CA3-41A7-A5B0-CC4A63449C8C

(Figures 5–8)

Type material

Holotype, female, Korsakovsky District, Sakhalin Island, Russia, 46°51′22.4″N 143°07′01.4″E, 10 August 2021, O. Joharchi coll., in the nest of Formica gagatoides Ruzsky (Hymenoptera: Formicidae). Paratypes, six females and a male, same data as holotype.

Diagnosis (adult female)

Dorsal shield bearing 39 pairs of long setae, including three unpaired supernumerary setae Jx (in all examined specimens, without variation), mostly barbed distally, length of setae slightly increasing from anterior to posterior, mostly long enough to reach base of next setae in series, vertical setae (j1) and z1 shortest; clunal setae (Z5) longest (Z5 ≈ 1.5 x J5), vertical (j1) and clunal setae (Z5) not conspicuous. Sternal shield slightly longer than wide, posterior margin almost straight and anterior margin slightly convex. Anal shield pear-shaped, with anterior margin slightly concave and anterolateral angles widely rounded. Fixed digit of chelicera with a shallow tooth, movable digit edentate.

Description (adult female)

Six specimens measured.

Dorsal idiosoma — (Figures 5A & 8A) — Dorsal shield oval, 480–490 long, 320–330 wide, regularly tapering from level of S1, reticulate on marginal and posterior surface (anteromedial region smooth); bearing 39 pairs of pilose setae (with 2–6 min barbs distally): 22 pairs of podonotal and 17 pairs of opisthonotal setae, including two pairs of Zx setae between J and Z setae and three unpaired supernumerary seta Jx between J-series (in all examined specimens, without variation), all setae similar in length (40–55), length slightly increasing from anterior to posterior, most setae long enough to reach base of next setae in series, vertical setae (j1) (26–29) and z1 (15–17) shortest; clunal setae (Z5) longest (58–61) (Z5 ≈ 1.5 x J5). Dorsal shield with 20 pairs of discernible pore-like structures, including four pairs of gland openings (gd1, gd4, gd8, gd9) and 16 pairs of poroids. Shape, position and relative length and thicknesses of setae shown in Figures 5A & 8A.

Ventral idiosoma — (Figures 5B & 8B) — Tritosternum with paired pilose laciniae (65–74), fused basally (7–9), columnar base, 17–20 in length and width; presternal platelets absent. Sternal shield (length 118–125) narrowest between coxae II (100–106), widest at level of endopodal between coxae II and III (155–162), posterior margin almost straight and anterior margin slightly convex, shield with three pairs of subequal and smooth sternal setae st1-3 (30–33), not reaching base of following setae and two pairs of poroids (iv1 and iv2 slit-like, adjacent to setae st1 and between st2 and st3, respectively) (Figures 5B & 8B); surface without reticulate ornamentation, almost smooth, except some irregular longitudinal lines laterally, shield fused anterolaterally to narrow endopodal strip between coxae I and II, and to endopodal between coxae II and III. Metasternal setae st4 (33–35) and metasternal poroids iv3 inserted on soft cuticle posterior to sternal shield; metasternal platelets absent. Endopodal plates II/III completely fused to sternal shield, endopodal plates III/IV elongate, narrow, and curved. Genital shield elongated, rounded posteriorly, slightly protruding at level between setae st5 and Zv1, width (118–126) and length (235–245), anterior hyaline margin curved, reaching to level between iv2 and st3; shield ornamented posteromedially by eight cells flanked by a median Λ-shaped ornamentation, bearing smooth genital setae st5 (33–35) on edges (Figures 5B & 8B). Shield flanked by a pair of minute elongate paragenital platelets, paragenital poroids (iv5) located on soft cuticle lateral to shield behind st5. Anal shield pear-shaped, length 84–88, width 71–76, with anterior margin slightly concave and anterolateral angles widely rounded, a pair of lateral poroids (gv3) on lateral margins, anterior half lineate-reticulate; post-anal seta (38–40) slightly thicker and longer than para-anals (30–33), cribrum consisting of a terminal tuft with 3–4 irregular rows of spicules, anterior most row of spicules extending slightly beyond post-anal seta (Figures 5B & 8B). Soft opisthogastric cuticle surrounding genital and anal shields with one pair of suboval metapodal plates (25–28 long × 5–7 wide) and 15 pairs of setae (Jv1–Jv5, Zv1 – Zv5, R1–R4, r6); setae different in length (25–57) and thickness, Jv5 (25–57) longest, some setae sparsely barbed distally (with 2–4 min barbs), all setae arising on small sclerotized platelet; shape, position and relative length and thicknesses of setae shown in Figures 5B & 8B. Peritreme long, extending to level between z1–s1 (anterior level of coxa I), peritrematal shield narrow, expanded anteriorly, free from exopodal shields, each shield bearing five discernible pore-like structures, a lyrifissure ip and a gland pore gp at level of coxa II, two lyrifissures ip and a gland pore gp on poststigmatic section (Figures 5B & 8B); anterior part of shield not fused with dorsal shield.

Gnathosoma — (Figures 5C-E & 8C-D) — Epistome subtriangular, with pointed apex (Figure 5D), corniculi short and with completely rounded apex; internal malae long, with tips well exceeding the corniculi, pointed, finely fringed; labrum longer and blade-like (Figure 5C), hypostomal and capitular setae smooth, h3 (40–42) < h1 (26–28) < pc (18–20) < h2 (16–18) ; hypostomal groove with six rows of denticles, all rows connected by lateral margins of groove, each row bearing 7–18 denticles, groove progressively narrowing from anterior to posterior ends (Figure 5C). Chaetotaxy of palps: trochanter 2, femur 5, genu 6, tibia 14, tarsus 15, all setae smooth and needle-like except al1, al2 on palp genu and al, d3 on palp trochanter thickened, al2 paddle-like on palpgenu, palp tarsal apotele two-tined; shape, position and relative length of setae shown in Figure 8C. Fixed digit of chelicera with a distal shallow tooth associated with short pilus dentilis, dorsal seta thick and prostrate; movable digit edentate, arthrodial membrane with a rounded flap and normal filaments (Figures 5E & 8D).

Insemination structures — Not seen, apparently unsclerotized.

Legs — (Figure 6) — Legs II and III short (320–330, 304–310), I and IV longer (460–470, 414–419) (excluding pretarsus). Chaetotaxy normal for free-living Laelapidae: Leg I (Figure 6A): coxa 0–0/1, 0/1–0, trochanter 1–0/1, 1/2–1 (al and pd thickened, spinelike), femur 2–3/1, 3/3–2 (ad1 and ad3 thickened, ad1 inserted on small tubercle), genu 2–3/2, 3/1–2, tibia 2–3/2, 3/1–2. Leg II (Figure 6B): coxa 0–0/1, 0/1–0, trochanter 1–0/1, 0/2–1 (al slightly thickened), femur 2–3/1, 2/2–1 (ad1-3 slightly thickened), genu 2–3/1, 2/1–2, tibia 2–2/1, 2/1–2. Leg III (Figure 6C): coxa 0–0/1, 0/1–0, trochanter 1–1/1, 0/1–1 (al, ad, pv slightly thickened), femur 1–2/1, 1/0–1 (ad1 and ad2 slightly thickened), genu 2–2/1, 2/1–1, tibia: 2–1/1, 2/1–1. Leg IV (Figure 6D): coxa 0–0/1, 0/0–0, trochanter 1–1/1, 0/1–1 (ad slightly thickened), femur 1–2/1, 1/0–1, genu 2–2/1, 3/0–1, tibia 2–1/1, 3/1–2. Tarsi II–IV with 18 setae (3–3/2, 3/2–3 + mv, md). All pretarsi with paired claws, rounded pulvilli, and a long thin stalk.

Description (adult male)

(Figures 7–8)

One specimen measured.

Dorsal idiosoma — Dorsal shield 368 long, 229 wide; ornamentation and chaetotaxy as in female.

Ventral idiosoma — (Figures 7A & 8E) — Sternal, genital, endopodal, ventral and anal shields fused into holoventral shield, 321 long from anterior to posterior margins of shield, 84 wide at level of st2, 89 at st3 level and 123 at broadest point (behind parapodals), anterolateral edges of shield fused to endopodals between coxae I-II; shield reticulate throughout, with five pairs smooth sternal setae (st1–5), and four pairs of smooth ventral setae (Jv1, Jv2, Zv1, Zv2), plus three smooth circumanal setae, post-anal seta 27 longer and thicker than para-anals (20), with five pairs of poroids and a pair of gland pore (gv3) on lateral margins of shield at anterior level of anal opening, iv1 slit-like; gland pore gv2 behind coxa IV not discerned; cribrum with 3–4 irregular rows of spicules; metapodal platelets oval and free from the shield (Figures 7A & 8E). Soft opisthogastric cuticle with nine pairs of setae, and four pairs of poroids. Peritremes, peritrematal shields and other ventral structures similar to those in female.

Gnathosoma — (Figures 7B and 8F) — Fixed digit of chelicera reduced, edentate, pilus dentilis not discernible; movable digit not distinct, fully transformed into very long sinuate spermatodactyl (170), progressively tapering into a blunt apex, bent downward at the tip, dorsal seta not discernible (Figures 7B and 8F). Other gnathosomal structures similar to those in female.

Legs — Chaetotaxy as in female.

Immature stages — Unknown.

Etymology

The species name refers to the noticeable long spermatodactyl; macrodactyla is a latinized noun derived from the Greek words makros-(''long'') + daktylos-(''finger'').

Remarks

According to Babaeian et al. (2019) and the identification key to Holostaspis species provided in this publication, H. macrodactyla Joharchi most resembles Holostaspis collina (Huhta and Karg, 2010) and Holostaspis submontana (Bai, Gu and Chen, 1994) (last couplet in the identification key), but H. macrodactyla can easily be distinguished from both species by having very long pilose dorsal setae, most setae long enough to reach base of next setae in series, peritreme long, extending to anterior level of coxa I, while neither of these character states is seen in the above mentioned species. Furthermore, posteromedial dorsal surface with three unpaired supernumerary setae between J series and hypostomal groove progressively narrowing from anterior to posterior ends in H. macrodactyla, while H. submontana with a single unpaired accessory seta and hypostomal groove with regular width. Holostaspis michaeli (Joharchi, 2013; in Joharchi and Moradi 2013) may be similar to H. macrodactyla Joharchi in general appearance, but H. michaeli has a short peritreme nearly extending to middle of coxa II and without unpaired accessory setae between J1–J5. The following key is based on direct examination of all species.

Key to species of Holostaspis occurring in the Russia, partly from Babaeian et al. 2019

1 Medial cheliceral segment and movable digit robust, stumpy and a sharp terminal hook on movable digit present (Figures 2E & 3D), anal shield usually with acuminate anterolateral extensions (Figure 3B)
...... 2

— Medial cheliceral segment and movable digit weakly sclerotized, emaciated, sharp terminal hook on movable digit absent (Figures 5E & 8D), anal shield without acuminate anterolateral extensions (Figure 8B)
...... 4

2. Podonotal and opisthonotal setae similar in length
...... Holostaspis isotricha Kolenati, 1858

— Opisthonotal setae 1.5–3 times as long as podonotal setae
...... 3

\cledetermination{3. Posteromedial dorsal surface with five unpaired supernumerary setae between J series, vertical setae (j1) and setae of dorsal hexagon (j5, z5, j6) similar in length, movable digit of chelicera with two subapical denticles}

{Holostaspis intermedia Joharchi n. sp. }

— Posteromedial dorsal surface with one unpaired supernumerary setae between J series, vertical setae (j1) 1.5 times as long as setae of dorsal hexagon, movable digit of chelicera only with a small rounded subdistal bulge
...... Holostaspis oophila (Wasmann, 1897)

4. Dorsal shield not completely covering dorsal idiosoma, exposing strips of lateral and posterior soft integument, tibia III and genu III–IV with two posterolateral setae (pl1, pl2) and femur I bearing five ventral setae
...... Holostaspis flexuosa (Michael, 1891)

— Dorsal shield completely covering dorsal idiosoma, tibia III and genu III–IV with only one posterolateral setae and femur I bearing four ventral setae
...... 5

\cledetermination{5. Dorsal shield with very long and pilose setae, almost all setae well reaching base of following setae}

{Holostaspis macrodactyla Joharchi n. sp. }

— Dorsal shield with short and smooth setae, barely reaching more than half the distance of following setae
...... 6

6. Vertical (j1) and clunal setae (Z5) conspicuous, j1 longer than other anteromedial setae (j2–j6) and Z5 about two times longer than S5
...... Holostaspis montana (Berlese, 1904)

— Vertical (j1) and clunal setae (Z5) not as conspicuous, j1 not longer than other anteromedial setae (j2–j6), setae Z5 and S5 similar in length
...... Holostaspis ambigua Babaeian, Mašán and Halliday, 2019

Acknowledgements

The present research was supported by the grant from the Russian Science Foundation, project number 20–64–47015. We cordially thank Dr. Alexander Khaustov and Mr. Roman Latyntsev (Tyumen State University, Russia) for their help in collecting samples, and in logistics, respectively.

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