Holostaspis isotricha Kolenati, 1858

Babaeian, Esmaeil, Mašán, Peter & Halliday, Bruce, 2019, Review of the genus Holostaspis Kolenati, 1858 (Acari: Laelapidae), Zootaxa 4590 (3), pp. 301-341 : 317-320

Holostaspis isotricha Kolenati, 1858

( Figs 33–43 )

Holostaspis isotricha Kolenati, 1858: 87 .

Holostaspis isotricha .— Oudemans, 1914: 68 (in part); Bregetova, 1977: 549; Keum et al., 2017: 490.

Hypoaspis (Holostaspis) isotricha .— Evans & Till, 1966: 159, 203; Karg, 1971: 177; Karg, 1979: 97; Karg, 1982: 248; Karg, 1993: 157.

Specimens examined. Sixteen females, SW Slovakia, Považský Inovec Mountains, Lúka Village, Srnia Dolina Valley (48°40'40" N, 17°53'03" E), edge of deciduous forest and meadow, in anthill of Formica pratensis Retzius, 1783 ( Hymenoptera , Formicidae ), altitude 270 m, 9 April 2006 (15 females), 2 December 2006 (1 female), coll. P. Mašán.

Diagnosis (female). Dorsal shield oval to ovoid, mostly smooth except weakly reticulate on lateral margins, bearing 39 pairs of pilose setae and one or two unpaired accessory setae between J1–J3; dorsal setae with terminal pilosity, relatively long, slightly increasing in length from anterior to posterior, and with tips reaching bases of following posterior setae in opisthonotal region; vertical setae (j1) as long as most of podonotal setae; setae z1 shortest. Sternal shield wider than long, strongly concave posteriorly, smooth throughout. Anal shield subtriangular, anterior margin concave and anterolateral angles pointed; postanal seta thickened and approximately 1.5 times as long as adanals. Peritremes relatively short, with anterior ends not reaching level of s1. Epistome with anterior margin broadly rounded. Fixed digit of chelicera with bidentate terminal hook associated with short pilus dentilis, movable digit with a small, sharp terminal hook and two subapical denticles.

Description. Female (n=6)

Dorsal idiosoma ( Fig. 33 ). Idiosoma 626–656 µm long and 403–411 µm wide; dorsal shield oval, 601–619 µm long and 307–342 µm wide, smooth medially, with uneven lineate-reticulate ornamentation on lateral surface; bearing 39 pairs of setae: 22 pairs (j1–j6, z1–z6, s1–s6, r2–r5) in podonotal area and 17 pairs (J1–J5, Z1–Z5, Px2–Px3, S 1– S 5) in opisthonotal area and two unpaired accessory setae between J1–J5; with at least 21 pairs of discernible pore-like structures (five pairs of gland pores and 16 pairs of lyrifissures). All dorsal shield setae (except z1) sparsely and delicately pilose in apical third ( Fig. 34 ), relatively thick and long and progressively elongated posteriorly (opisthonotal setae slightly longer than those on podonotum).

Ventral idiosoma ( Fig. 35 ). Tritosternum with columniform base (30–35 µm) and sparsely pilose laciniae (56–61 µm). Sternal shield subrectangular, 99–102 µm long and 119–124 µm wide (L/W=0.83), widest at level of coxae II–III (188–198 µm), convex anteriorly (except shallow medial concavity) and widely concave posteriorly; whole surface smooth, without sculptural ornamentation; setae slender, relatively longer, with tips almost reaching bases of following ones (st1 37–45 µm, st2 37–52 µm, and st3 40–52 µm); lyrifissures iv1 and iv2 slit-like. Metasternal setae (st4 42–45 µm) and associated lyrifissures iv3 placed on soft integument; endopodal platelets III–IV subtriangular, narrow and free from posterolateral margins of sternal shield. Epigynal shield tongue-shaped, elongate, 295–319 µm long and 166–173 µm wide (129–144 µm at level of st5); anterior hyaline margin curved, reaching close to level of sternal setae st2; posterior portion with rounded margin and lineate ornamentation pattern forming usually nine elongate cells; genital setae (st5 42–49 µm) and associated lyrifissures iv5 placed on the shield (close to or on its mediolateral margins, respectively); soft integument between iv5 and Zv1 each with one minute and narrow adgenital sclerite. Metapodal platelets elongate, 57–64 µm long. Anal shield subequal in length and width (69–84 µm long and 75–80 µm wide), with anterolateral angles sharply pointed and weak sculptural lines on anterior portion; postanal seta 50–54 µm long, thickened and longer than adanal setae (27–35 µm); cribrum with wide band of spicules. Lateral and opisthogastric soft integument with 17 pairs of setae; setae different in length (37–92 µm), each with base inserted in small and rounded scutal structure; setae r6, R1, Jv1–Jv3, Zv1 and Zv2 shorter and smooth, other longer and sparsely pilose distally. Poststigmatic section of peritrematal shield narrow, tapered posteriorly.

Gnathosoma ( Figs 36–39 ). Anterior margin of epistome regularly rounded, sparsely with shallow incisions ( Fig. 36 ). Corniculi short and pointed, horn-like; internal malae relatively short, with tips only slightly exceeding the corniculi, abutting each other, projecting medially and finely serrate laterobasally; labrum longer and blade-like ( Fig. 37 ). Deutosternal furrow on ventral subcapitulum with almost parallel lateral margins, with six transverse rows of denticles (each with 6–9 denticles). Lengths of hypostomal and palpcoxal setae: h 1 30–32 µm, h 2 22–25 µm, h3 37–42 µm, pc 32–42 µm. Palp setation 2-5-6-14 -15, as in Fig. 37 . Shape and dentition of chelicera as in Figs 38–39 ; lengths of cheliceral articles: the second segment 97–104 µm, fixed and movable digit each 17 µm.

Legs ( Figs 40–43 ). Tarsi I–IV each with a pair of claws and pulvillus. Lengths of legs: leg I 334–351 µm, leg II 260–280 µm, leg III 265–280 µm, leg IV 344–389 µm. Seta al on trochanter II, al2 on femur II, al on femur III, al, pl and av on femur IV, av and pv on genu II and tibia II, and ventral setae on genua III–IV and tibiae III–IV slightly thickened; seta al on trochanter III and ad on trochanter IV, ad1 on femur II, and ad1 on femora III–IV thickened.

MALE. Unknown.

Remarks. Oudemans (1914) considered H. isotricha as a synonym of H. oophila . Later authors disagreed and accepted both as valid species. Unfortunately, the type specimens of H. isotricha are probably lost and not available for study, and the original description of the species by Kolenati (1858) is not detailed enough to allow confident recognition and even genus-level classification. The relatively elongate idiosoma and short dorsal shield setae, as depicted in Kolenati’s original illustrations, are more similar to other Holostaspis species than H. isotricha . Nevertheless, in the interests of stability, we follow Evans & Till (1966) in their concept of this species based on the specimens from Scotland, although they give no reasons as to why they identified their specimens as H. isotricha . There do not appear to be any specimens identified as H. isotricha in the Natural History Museum, London (J. Beccaloni, personal communication). Our specimens were collected from Lúka Village, 100 km southeast of the type locality, Brno, and agree very well with the description and illustrations in Evans & Till (1966).

Figures

FIGURES 33–39. Holostaspis isotricha, female. 33. Dorsal idiosoma; 34. Enlarged view of a dorsal seta; 35. Ventral idiosoma; 36. Epistome; 37. Ventral gnathosoma with palp; 38. Chelicera; 39. Chelicera, with detailed view of the cheliceral digits and their dentition.

FIGURES 40–43. Holostaspis isotricha, female. 40. Leg I; 41. Leg II; 42. Leg III; 43. Leg IV.