Onchodellus anatolicus Özbek & Akyol, 2025

Özbek, Hasan Hüseyin, Akyol, Hicran & Demir, Derya, 2025, New records and new species of Pachylaelapidae (Acari: Mesostigmata) from Erzincan Province, Türkiye, Zootaxa 5706 (2), pp. 264-278 : 265-268

Onchodellus anatolicus Özbek & Akyol sp. nov.

( Figs 1–12 )

Diagnosis (Adults)

Posterodorsal setae J4 and J5 distinctly different in length; dorsal shield with two pairs of posterolateral slit-like gland pores ( gdZ1, gdS4) present, gdZ1 positioned between setae Z1 and Z2; anterior ends of peritremes extending over dorsal side of shield and positioned between setae z1 and z2. In female, soft integument of idiosoma with 12 pairs of setae (five pairs marginal, seven pairs opisthogastric); genitiventral shield wider than long; femur II with ventral projection associated with a seta. In male, spermatodactyl very long, slightly narrowing towards the distal section, with a length more than three times that of the movable digit; tarsus II with a spur-like seta p11 and small opposite mediolateral apophysal spur; apophysal spur distinctly shorter than pl1; femur II with large, finger-like process; genu II and tibia II each with distinct ventral process.

Type material. Holotype, female from moss, 39°12’N 38°36’E, 1031 m a.s.l., 08 March 2024 . Paratypes: 1♀ and 2♂♂, the same data as in holotype ; 1♂ from litter and moss, 39°38’N 38°27’E, 1000 m a.s.l., 24 April 2023 ; 2♀♀ from litter under Astragalus sp. , 39°12’N 38°36’E, 1031 m a.s.l., 08 March 2024 ; 3♀♀ and 3♂♂ from moss, 39°12’N 38°36’E, 1031 m a.s.l., 08 March 2024 —the Karasu Valley (Kemaliye) .

Description. Female

Dorsum ( Fig. 1 ). Dorsal shield 485–540 long, 250–292 wide at its widest point, length/width ratio 1.78–1.97, oval, surface reticulate, with 30 pairs of smooth, pointed setae and two pairs of posterolateral slit-like gland pores ( gdZ1 and gdS4), gdZ1 positioned between setae Z1 and Z2. Dorsal setae j1 18–21, z1 10–12, J4 46–50, J5 17–20 long, J4 / J5 ratio 2.47–2.70. Other dorsal setae 30–50 long, except s2, s6, r5, S1, and S3, 25–30.

Venter ( Figs 2 , 10 ). Sternal shield 170–185 long, 80–94 wide at the level of coxae II, surface ornamented with a reticulate pattern, with four pairs of pointed setae and three pairs of pores, st1–4 (30–45). Genitiventral shield 160–197 long, 180–200 wide, wider than long, length/width ratio 0.87–0.99, ornamented with a polygonal pattern, with two pairs of setae ( st5 30–38, Jv1 40–46). Anal shield 65–71 long, 96–116 wide, length/width ratio 0.60–0.67, triangular, surface without ornamentation. A pair of rod-shaped metapodal shields present. Lateral and opisthogastric soft integument with 12 pairs of setae (five pairs marginal, seven pairs opisthogastric). Anterior ends of peritremes extending to the dorsal side of idiosoma, positioned between setae z1 and z2.

Spermathecal apparatus. Sperm access system connected to coxae III, tubes long, apical section slightly widening ( Fig. 2 ).

Gnathosomal structures. Hypostome with seta h3 longest, h2 and palp coxal seta pc shortest and subequal in length; corniculi horn-like and lanceolate, deutosternal groove with six rows of denticles. Epistome with straight denticulate lateral margins and central projection with strong apical denticle ( Fig. 3 ). Movable digit about about 56 long, with two large subdistal tooth, a small subdistal tooth, and unidentate terminal hook; fixed digit about 56–58 long (to dorsal seta), with a minute pilus dentilis ( Figs 4 , 11 ). Arthrodial brush short.

Legs. Chaetotaxy normal for the genus ( Mašán, 2007). Femur II with ventral projection associated with a seta ( Fig. 5 ), and tarsus II with a thicker spur-like seta pl1 ( Fig. 6 ).

Description. Male

Dorsum. Dorsal shield 446–472 long 240–270 wide at the level widest point (length/width 1.70–1.95), suboval and oblong, setae J4 36–46, J5 16–20, rate of J4 / J5 2–2.5. Two pairs of posterolateral slit-like gland pores ( gdZ1 and gdS4) present. Ornamentation and dorsal chaetotaxy as for female.

Venter. Holoventral shield ornamented with the reticulate pattern and bearing 5 pairs of needle-like setae and 3 pairs of pores. Opisthogastric region of the shield with three pairs of setae, three circum-anal setae.

Gnathosomal structures. Epistome as in female. Movable digit of chelicerae 48–50 long, with a large subdistal tooth and a prominent terminal hook ( Fig. 7 ). Spermatodactyl very long, slightly narrowing towards the distal section (185–190 long), with a length 3.7–3.95 times that of the movable digit ( Fig. 12 ). Fixed digit 49–52 long, bearing a subdistal tooth, and a large terminal hook, with pilus dentilis clearly visible. Palptibiae without any processes. Arthrodial brush short.

Leg II. Femur with large, finger-like process; genu and tibia each with distinct ventral process ( Fig. 8 ). Tarsus with a spur-like seta p11 and small opposite mediolateral apophysal spur; apophysal spur distinctly shorter than pl1 ( Fig. 9 ).

Etymology. The species is named after Anatolia, a region in Türkiye where it was first discovered.

Remarks: The species Onchodellus anatolicus sp. nov. belongs to the O. strigifer group, which was established by Mašán (2007) based on the presence of two pairs of slit-like gland pores ( gdZ1, gdS4), the structure of the spermatodactyl, and the length of the J5 seta. It can be compared to the seven previously described species in this group ( Özbek & Halliday, 2024).

Onchodellus anatolicus sp. nov. can be easily distinguished from most species of this group by the number of setae on the soft integument, which varies among species as follows: 12 pairs in O. anatolicus and O. striatifer ; 11 pairs in O. strigifer (Berlese, 1892) and O. montanus Şahin & Özbek, 2018 ; 14 pairs in O. neglectus Mašán, 2007 ; 10 pairs in O. slovacus Mašán, 2007 ; and 13 pairs in O. tegulifer Mašán, 2007 , O. kosensis Özbek, 2023 , and O. marginatus Özbek & Halliday, 2024 . Although O. anatolicus shares the same number of setae with O. striatifer Mašán, 2007 , it differs in several morphological features, including the shape of the idiosoma, the ornamentation of the dorsal shield, the significantly longer J5 setae (16–20 long in O. anatolicus ; 8–13 in O. striatifer ), and a longer spermatodactyl in males (185–190 O. anatolicus ; 120–140 in O. striatifer ).

Figures

FIGURES 1−2. Onchodellus anatolicus sp. nov., female. 1. Dorsal idiosoma; 2. Ventral idiosoma with spermathecal apparatus.

FIGURES 3−9. Onchodellus anatolicus sp. nov. 3. Female, epistome; 4. Female, chelicera; 5. Female, femur II; 6. Female, tarsus II; 7. Male, chelicera; 8. Male, femur, genu and tibia of leg II; 9. Male, tarsus II.

FIGURES 10−12. Onchodellus anatolicus sp. nov. 10. Female, Ventral shields; 11. Female, chelicera; 12. Male, chelicera.