Pachylaelaps (Pachylaelaps) imitans Berlese, 1920

Özbek, Hasan Hüseyin & Halliday, Bruce, 2024, Two new species of mites in the family Pachylaelapidae from Türkiye (Acari: Mesostigmata), Zootaxa 5514 (4), pp. 319-337 : 329-333

Pachylaelaps (Pachylaelaps) imitans Berlese, 1920

( Figs 37–45 )

Pachylaelaps imitans Berlese, 1920: 184 .

Pachylaelaps imitans .— Sellnick, 1931: 746; Hirschmann & Krauss, 1965: 5; Costa, 1971: 258; Koroleva, 1977b: 421, 468; Castagnoli & Pegazzano, 1985: 192; Karg, 1993: 120 (in part: male leg II only); Mašán, 2007a: 206.

Pachylaelaps (Pachylaelaps) imitans .— Karg, 1971: 143 (in part: male leg II only); Mašán, 2007a: 206; Mašán & Halliday, 2014: 35 .

Pachylaelaps pratensis Karg, 1965: 268 (in part: male leg II only).

Diagnosis (Adults)

Dorsal setae J5 microsetae; two pairs of posterolateral poroid structures (gdZ1, gdS4) with teat-like openings, these pores extremely close to each other; surface of sternal shield ornamented with irregular web-like lines and two distinct roof-shaped lines; genitiventral shield distinctly longer than wide; peritremes with anterior end extending to dorsal surface but not reaching base of setae z1. In female, lateral and ophistogastric soft integument with 15 pairs of setae; the tubes of the spermathecal system look bipartite, well sclerotized and lie between the coxae IV. In male, spermatodactyl of male more than twice as long as movable digit, becoming narrower towards distal part and basally with a well-developed semicircular process; palptibiae each with two distinct processes, one well-developed and triangular, another distinctly longer and pointed distally; femur II with a large spur-like process with a seta close to its base.

Material examined. 17 females and one male, Türkiye, Gümüşhane Province, Çakırkaya village (40° 09’ N, 39° 04’ E), altitude 1335 m a.s.l., litter under Astragalus sp. , 13 April 2012 .

Description. Female.

Dorsum ( Fig. 37 ). Dorsal shield 890–970 long and 540–600 wide, suboval and elongate (length/width 1.5–1.7), finely and evenly reticulate over entire surface and with 30 pairs of smooth and pointed dorsal setae, J5 microsetae. Setae j1 45–55, j5 60–70, z1 about 35, z5 60–65, length of dorsa-lateral setae s2, r2, r3, r5, s6, S1, S3 70–80, other dorsal setae 80–120 long. Two pairs of posterolateral poroid structures (gdZ1, gdS4) with teat-like openings, between setae Z2 and S4, these pores extremely close to each other.

Venter ( Fig. 38 ). Sternal shield 270–300 long, 140–160 wide at level of coxae II, its surface decorated with irregular web-shaped lines and two distinct roof-shaped lines beginning behind base of coxae IV and separating at middle level of coxae III. The first lines extends to the area between sternal setae st1, the shorter second line to the middle of coxae II. Seta st1 (about 110) longest, other sternal setae uniform in length (70–90). Genitiventral shield distinctly longer than wide (length 300–380, width 260–320, length/width 1.09–1.26), ornamented with reticulate lines, with two pairs of setae. Anal shield subtriangular, 110–140 long and 150–190 wide (length/width 0.65–0.85); anus with three long circum-anal setae near posterior margin of shield, ornamented with reticulate lines. Peritremes with anterior end extending to dorsal surface but not reaching base of z1. Metapodal platelets large, free and separated from peritrematal shields. Lateral and opisthogastric soft integument with 15 pairs of setae (six pairs of marginal and nine pairs of opisthogastric).

Spermathecal apparatus. Tubes well sclerotised, arising between coxae IV. Base of tube thicker, distal part slenderer and variable, end of tubes directed anteriorly, posteriorly or laterally in various specimens ( Figs 39, 40 ).

Gnathosomal structures. Corniculi elongate and lanceolate. Deutosternal groove with six rows of denticles. Epistome with straight denticulate lateral margins and central projection with strong apical denticle. Chelicera well developed with strong subdistal teeth; movable digit about 140–150 long, with one large subdistal tooth and one distal denticle near unidentate terminal hook; fixed digit about 130 long (to dorsal seta), with one large subdistal teeth, multidentate terminal hook, and pilus dentilis ( Fig. 41 ). Arthrodial brush short.

Legs. Leg setation normal for the genus ( Mašán, 2007a). Femur II with small process with associated seta ( Fig. 42 ), and tarsus II with two spur-like distal setae, pl1 and pl2 ( Fig. 43 ).

Description. Male.

Dorsum. Dorsal shield 800 long, 517 wide at the widest point (length/width 1.54), suboval. Ornamentation and dorsal chaetotaxy as for female.

Venter. Holoventral shield 684 long, 148 wide at the level of coxae II, ornamented with reticulate pattern and bearing nine pairs of setae (plus three circum-anal setae). Dorso-lateral and opisthogastric soft integument with 13 pairs of setae.

Gnathosoma . Moveable digit of chelicera 88 long, with a subdistal tooth and a terminal hook, spermatodactyl 212 long, more than twice as long (2.40) as the movable digit, narrowing towards the distal part, and basally with a well-developed semicircular process. Fixed digit 79 long, with subdistal tooth and unidentate terminal hook ( Fig. 44 ). Palpfemur with distinct process connected by a seta; palptibiae each with two distinct processes, one well developed and triangular, another distinctly longer and pointed distally.

Leg II. Femur II with large, leaf-shaped, spur-like process connected to a seta; genu and tibia with small processes, tarsus II with a large spur-like seta pl1 ( Fig. 45 ).

Remarks

This species is mainly found in warmer regions: the eastern Mediterranean and the area between the Black Sea and the Caspian Sea. It has already been described and illustrated several times ( Sellnick, 1931; Costa 1971; Koroleva, 1977b). Koroleva (1977b) considered Pachylaelaps pratensis Karg, 1965 to be a synonym of P. imitans , but Mašán (2007a) and Mašán & Halliday (2014) clarified the confusing misidentifications involving P. pratensis and P. insularis Berlese, 1920 . The species is redescribed here on the basis of DIC (Differential Interference Contrast) photographs and detailed measurements of male and female specimens. The aim is to determine morphological variations in relation to the distribution of the species in this zoogeographical region. This should facilitate and clarify the identification of the species. Moreover, this species is a new record for the fauna of Türkiye.

Compared to previously described specimens, (1) the idiosoma and dorsal shield of the females of P. imitans are regularly oval (see Koroleva 1977b) or slightly broadened in the posterior region ( Costa, 1971). In the specimens from Türkiye, the dorsal shield is widened in the anterior part, especially at the level of the humeral setae. (2) The posteromedial margin of the genitoventral shield in P. imitans is known as a straight or only slightly convex structure, which normally closely follows the anterior margin of the anal shield. In the specimens from Türkiye it is regularly convex (not only at the posterolateral corners as in other descriptions) and slightly distant from the anal shield (not directly adjacent to the anal shield as in other descriptions). (3) The basal process of the spermatodactyl of the male is triangular (see Koroleva, 1977b) or slightly pronounced (see Hirschmann and Krauss, 1965), in the specimens from Türkiye it is well pronounced and semicircular. (4) The small process of genu II of the male is not pointed (see Koroleva, 1977b), in the specimen from Türkiye it is clearly pointed.

Figures

FIGURES 37–38. Pachylaelaps (Pachylaelaps) imitans, female. 37. Dorsal shield; 38. Ventral idiosoma.

FIGURES 39–45. Pachylaelaps (Pachylaelaps) imitans. 39. Female, spermathecal apparatus directed anteriorly; 40. Female, spermathecal apparatus directed laterally; 41. Female, chelicera; 42. Female, femur II; 43. Female, tarsus II; 44. Male, chelicera; 45. Male, leg II.