Four new species of Halozercon (Acari: Mesostigmata: Zerconidae) from South Siberia Mountains (Russia) with a key to all known species Author Marchenko, Irina I. text Zootaxa 2021 2021-03-08 4941 2 151 185 journal article 10.11646/zootaxa.4941.2.1 1175-5326 4594890 30905E3C-34E8-4FDD-8CAA-6F621252A149 Halozercon aesopi sp. n. Diagnosis. Dorsal idiosoma surrounded by very long plumose marginal setae on very high bases. Podonotum with pair of central rounded fields free of ornamentation. Central region of opisthonotum ornamented by tubercles and raised in the form of a hump. Vertex with pair of j1 setae and ip1 glands, z1 setae absent. In female, first and second sternal platelets divided; peritremes reaching level of anterior of coxae III. Gnathosoma with pair of arcs in the form of a crescent located meridionally near the pc setae; female chelicera typical for the genus. Pretarsus of legs II–IV with enlarged pair of median pulvillus with rounded top, significantly rises above the claws and paradactyls. Description. Female ( Figs 55–62 , n=5) Dorsal idiosoma ( Figs 55 , 61 ). Idiosoma suboval, 500–530 long and 325–340 wide. Anterior margin of the podonotum curved ventrally to form a vertex; only one pair of smooth j1 setae inserted on the ventral side of idiosoma 15–17 long, setae z1 absent, pair of glands ip1 inserted laterally of j 1setae. Podonotal setae of j , z and s - series and opisthonoal lateral setae located on small rounded bases. Podonotal shield neotrichous, with 40–41 setae of j , z , s -series, and 35–37 setae of r -series from each side. All setae of j , z , and s -series slightly pilose, most setae are shorter (17–22) than setae in most posterior row, 25–27 long. Podonotum without obvious ornamentation, with four pairs of pore-like structures po1–po4 , with a pair of central rounded fields of sigillae, free of ornamentation. Central area of opisthonotum neotrichous, with tubercles ornamentation and raised in form of a hump. Most anteriorly margin of opisthonotum with horizontal row of suboval sclerites. Central area with 25–31 curved, pilose setae in asymmetrical position, 27–29 long, lateral regions with six short, smooth setae (15–17), marginal R -rows with 22–24 setae from each side. Opisthonotal setae of median area located on enlarged rounded bases. All setae of r–R rows inserted on high bases (20–32 long), with long, density plumage (30–45 long), curved along idiosoma, total length of marginal setae with base is 62–65. Four pairs of pore-like structures Po1–Po4 inserted in opisthonotum. Ventral idiosoma . ( Figs 56 , 62 ). Base of tritosternum 25–27 long and 15–17 wide, paired pilose laciniae free from each other along entire length, 50–55 long. Pair of St 1 setae located on unsclerotised formations of soft cuticle, distinguishable using immersion. First sternal platelets divided suboval, 25–27 long and 17–22 wide; with pair of St2 setae and pair of lyrifissures iv2 . Second sternal platelet divided, irregular form, 20–30 long, 12–20 wide, with two pairs of setae St3 , St4 and one pair of lyrifissures iv3 . Area around the sternal shields covered with small tubercles. Genital shield 65–75 long, 47–55 wide, flask-shaped, expanded posteriorly; with genital setae St5 and lyrifissures iv5 . Sternal setae St1 17–20 the longest, other St2–St5 shorter 12–15. Subtriangular membrane is covered by the genital shield. Genital shield with complex genital formation typical for genus. Peritrematal shields fused anteriorly forming a vertex and fused with dorsal shield laterally; strongly sclerotised, postero-lateral ends are drawn back; ornamented with festoon reticulation along entire length. Four pairs of pore-like structures inserted in peritrematal shields: ip1 , ip3 and gp1 , and gp2 . Peritremes slightly sinuous, 98–102 long, reaching level of top of coxae III. Ventri-anal shield entire, broad, 137–150 long and 225–260 wide, fused to opisthonotal shield along the lateral margins, with festoon reticulation, with 6–8 smooth opisthogastric setae (15–17) from each side. Adgenital gland pores gv2 are multiple, dispersed over the surface: one pair of gland openings located in soft cuticle posterolaterally of genital shield, another 8–9 openings located in ventri-anal shield from each side. Anal area with short pilose para-anal (10–12) and smooth, post-anal setae, twice as long (18–20); anal opening with two lyrifissures on each valve; cribrum not expressed. Pair of glands gv 3 located anteriorly of para-anal setae. Gnathosoma . ( Figs 57–59 ). Fixed digit of chelicera 50–52 long, with five teeth in addition to apical hook and leaf-shaped pilus dentilis ( Fig. 57 ); movable digit the same length with three teeth in additional to apical hook. Chelicera with dorsal seta, antiaxial and dorsal (paraxial) lyrifissures; and arthrodial corona. Epistome with irregularly serrated lateral edges and smooth pointed median projection ( Fig. 58 ). Corniculi 25–27 long and 12–13 wide. Internal malae slightly longer than corniculi. Deutosternal groove with seven transverse denticulate rows ( Fig. 59 ), with three paired smooth lateral transverse lines. The posterior fourth pair of lateral transverse lines archshaped, with large denticles, located at the level of pc setae. Pair of relief arcs in the form of a crescent located meridionally near the pc setae. Setae h1–h3 smooth: h1 (31–33) longest, seta h2 (15–17) shorter than h3 (20–22); pc (17–20) serrated. Palpal chaetotaxy typical for the genus. Legs . ( Figs 60 , 63d ). Lengths: I 315–350, II 250–280, III 250–280, IV 315–350 μm. Chaetotaxy of legs typical for genus. All legs with pair of sclerotised claws and pulvillus. Pretarsus of legs II–IV with ambulacral stalk, with enlarged pair of median pulvillus with rounded top, significantly rises above the claws and paradactyls. Pretasus of I legs with sessile claws and pair of small median pulvillus. Coxae I–IV grouped closely together vertically; I coxae split on dorsal side, IV coxae with recesses on anterolateral side. Coxae II with antero-dorsal large sharp spine. Male and immature stages not found. Material examined . Holotype—female, Russia , ALTAI Mountains, Ust-Koksa Distr., Krasnaya Mountain., 50 05ʹ N , 85 11ʹ E , 900 m a.s.l., Picea obovata – Abies sibirica – Pinus sibirica forest, litter, 10 June 2013 , leg. I.I. Marchenko; paratypes— 4 females , same data as holotype . FIGURE 55. Halozercon aesopi sp. n . , female. Dorsal idiosoma. FIGURES 56–60. Halozercon aesopi sp. n . , female. 56. Ventral idiosoma; 57. Chelicera; 58. Epistome; 59. Hypostome with palp trochanter; 60. Pretarsus of legs II–IV. Etymology . The species aesopi named after the ancient Greek fabulist Aesop.Aesop became famous for writing fables about different animals and according to legend he was a humpback. Remarks . Dorsal idiosoma of Halozercon aesopi sp. n. differs from other species of genus by hump in the central part of opisthonotum and very long plumose marginal setae on very high bases.All dorsal pore-like structures enlarged. Opisthonotal lateral setae are few, about six. In vertex seta z1 indistinct (absent). Gnathosoma with pair of relief arcs in the form of a crescent located meridionally near the pc setae. Pretarsus of legs II–IV with enlarged pair of median pulvillus with rounded top significantly rises above the claws and paradactyls.