Sayanozercon, Marchenko, 2025

Genus Sayanozercon gen. nov.

Type species: Sayanozercon mariannae sp. nov.

Other included species: Sayanozercon adelaidae sp. nov., S. ergaki sp. nov., S. mikhaili sp. nov., S. shoricus sp. nov.

Diagnosis. The new genus is based on adult female and male material representing five newly described species. Adults of Sayanozercon gen. nov. can be distinguished from other genera of Zerconidae by the presence of an additional longitudinal latero-ventral shield extending between the peritrematal and ventrianal shields from setae r3 to R6; epistome with serrated central process with row of small median spines; smooth and acicular shape of all dorsal setae; podonotal setae z1 and z2 lost; unique morphology and sexual dimorphism of inguinal region with fibre brush of cuticular structure and two inguinal conspicuous poroids gvi and ivi; presence of pilus dentilis in fixed digit of chelicerae and sexual dimorphism of cheliceral denticulation – five teeth in female versus six teeth in male; sexual dimorphism of ventral chaetotaxy/porotaxy – setae st5, Zv1 lost in male and different location of gland gv2.

Description of Sayanozercon gen. nov.

Idiosomal dorsum. Large or mid-sized mites with rounded-oval or pear-shaped idiosoma, divided on two strongly sclerotised dorsal shields, without obvious ornamentation. All idiosomal setae smooth and pointed. Podonotal shield with 20 or 21 pairs of setae, setae z1 and z2 lost in all five species. Marginal seta r1 shortest in r -series, inserted at dorsal side, r3 seta is 3–4 times longer than r1 seta. Three podonotal glands are present, with various location of gland gdz5 (po3) in other species and five pairs of lyrifissures: idj1, idj3, idz4, ids4, idj6. Opisthonotal shield with 20–21 pairs of setae. Four podonotal glands present, with various location of gland gdZ1 (Po2) in other species. Opisthonotal shield with 13 pairs of lyrifissures: ids6, idS1, idz6, idS4, idZ4, idJ4, idJ5, idJ2, idJ3, doubled idJ1 and doubled idS3. Posterodorsal cavities rounded curvings, all equal size, located at posterior margin of opisthonotal shield.

Female venter. Additional latero-ventral shield is present, extending vertically from seta r3 to R6; with slight longitudinal reticulation. Peritrematal shields adjacent to additional latero-ventral shields anteriorly at level of coxae II and free at level of coxae III–IV. Peritrematal shield truncate at posterior margin, not fused with ventri-anal shield; with two conspicuous rounded poroids in inguinal region – gvi and ivi and fibre brush of cuticular structure. Peritrematal shields with smooth and pointed long setae r3; with lyrifissures ip1, ip2 and gland gp from each side. Peritremes very short. Large pair of endopodal sclerites between coxae III–IV with pair of setae st4 or outside sclerites. Adgenital sclerites presented each with 4–5 glands openings gv2. Ventrianal shield free, wide, with 21 smooth and pointed setae. Anal opening with two pairs of lyrifissures on each valve.

Male venter. Pair of latero-ventral shields shaped as in female, with reticulate ornamentation. Sternigenital shield with area of weak sclerotisation and weak reticulation between setae st1 and st2; with four pairs of setae (st1–st4), pair of st5 setae not developed, three pairs of lyrifissures and pair of glands gv1. Male peritrematal shields connected posteriorly to each other by fibre brush of cuticular structure; inguinal region with two pairs of conspicuous formations hollow inside—inguinal poroids gvi and ivi. Genital opening with two sclerites, eugenital setae present in S. mariannae sp.n. or not visible in other species. Ventrianal shield free, with multiple glands gv2 located on anterior margin; with 19 smooth and pointed setae; pair of setae Zv1 not developed.

Gnathosoma. Epistome with irregularly serrated lateral edges, serrated middle process with median row of small spines and medial ridge located posteriorly to row of spines. Chelicera with long dorsal seta, lateral (antiaxial) and dorsal lyrifissures; with smooth arthrodial corona and leaf-shaped pilus dentilis; apical sensorial depression presents. Sexual dimorphism of chelicerae denticulation: five teeth in female and six teeth in male. Deutosternal groove with seven transverse denticulate rows. Corniculi horn-like, internal malae extending beyond corniculi. Palpal chaetotaxy 2–5–6–12–15 with five free segments; pilose setae on palp trochanter v1 and v2; on palp femur d3, on palp genu al2; palp tarsal claw two-tined.

Legs. Legs of moderate length. All legs with pretarsi and paired claws. Pretarsus of legs II–IV with ambulacral stalk, tarsi I with sessile claws. Coxae I with dorsal incision, coxae II with antero-dorsal spine. Chaetotaxy of legs I–IV: coxae 2, 2, 2, 1; trochanters 6 (1 1/3 1), 5 (1 1/3 0), 5 (1 1/3 0), 5 (1 1/3 0); femora 13 (2 5/4 2), 11 (2 5/3 1), 6 (1 4/1 0), 6 (1 4/1 0); genua 13 (2 6/3 2), 11 (2 5/2 2), 10 (2 4/2 2), 10 (2 5/2 1); tibiae 14 (2 6/4 2), 10 (2 4/2 2), 9 (2 3/2 2), 9 (2 3/2 2); tarsi I–49 (6 29/9 5), II–IV 18 (3 7/5 3). Chaetotaxy of legs I–IV is typical for Zerconidae ( Halašková, 1969; Sikora, 2014). Legs of male without dimorphically modified setae.

Etymology. The genus name Sayanozercon reflects name of the Sayan Mountain in South Siberia, Russia. Gender feminine.

Species differential diagnosis.

A large number of characters differ between species of new genus Sayanozercon as shown in Table 1 View TABLE 1 and are listed below.

Idiosomal dorsum. Podonotal shield with 21 pairs of setae, seta s1 presented in S. adelaidae sp. nov., S. mikhaili sp. nov., S. shoricus sp. nov. and with 20 pairs of setae in S. mariannae sp. nov., S. ergaki sp. nov., where seta s1 is lost. Location of podonotal glands for all five species: gdj2 (po1) close to line connecting insertions of setae j2 and z3; gdj4 (po2) close to line connecting insertions of setae j4 and z4. Gland gdz5 (po3) usually located (for S. mariannae sp. nov., S. adelaidae sp. nov., S. ergaki sp. nov. and S. shoricus sp. nov.) close to line connecting insertions of setae z5 and s5, except for species S. mikhaili sp. nov., where it located near posterior edge of podonotal shield, close to line connecting insertions of setae s5 and z6. Opisthonotal shield with 20 pairs of setae in S. mariannae sp. nov., S. ergaki sp. nov., where four pairs of setae in J -series and 21 pairs of setae in S. adelaidae sp. nov., S. mikhaili sp. nov., S. shoricus sp. nov., where five setae in J -series. Seta J3 is lost in S. mariannae sp. nov. and seta J5 is lost in S. ergaki sp. nov. One species S. ergaki sp. nov. demonstrated sexual dimorphism of chaetotaxy: setae J3, J4 longest in female and shortest in male among setae in J- series. Opisthonotal adenotaxy presents different location of glands in other species. Location of opisthonotal gland gdZ1 (Po2) usually anterolateral to seta Z1 (species S. mariannae sp. nov., S. adelaidae sp. nov., S. ergaki sp. nov. and S. mikhaili sp. nov.), except for species S. shoricus sp. nov., where it placed on line connecting insertions of setae Z1 and Z2.

Idiosomal ventrum. Location of ventral setae st 4 in female varies among different species of Sayanozercon gen. nov. Setae st4 inserted on medial edge of endopodal sclerite in species: S. mariannae sp. nov., S. ergaki sp. nov. and inserted outside endopodal sclerite in species: S. adelaidae sp. nov., S. mikhaili sp. nov., S. shoricus sp. nov.

Gnathosoma. Three species: Sayanozecon mariannae sp. nov., S. ergaki sp. nov., and S. mikhaili sp. nov. demonstrated sexual dimorphism in denticulation of fixed digit of chelicera—five teeth in female and six teeth in male; structure of chelicerae of two other species is difficult to examine without dissection. Internal malae demonstrated two variations of structure: bifurcate apices in S. mariannae sp. nov., S. adelaidae sp. nov., S.shoricus sp. nov. and smooth pointed apices in S. ergaki sp. nov., S. mikhaili sp. nov.

Key to the species of the genus Sayanozercon gen.nov. (females)

1. Podonotal gland gdz5 (po3) located near to posterior margin of podonotal shield, close to line connecting insertions of setae s5 and z6....................................................................... Sayanozeron mikhaili sp. nov.

- Podonotal gland gdz5 (po3) located close and anterior to line connecting insertions of setae z5 and s5.................. 2

2. Setae s1 presented in podonotal shield, J -series with five pairs of setae on opisthonotal shield, mid-size of idiosoma 445–500 μm................................................................................................. 3

- Setae s1 lost in podonotal shield, J -series with four pairs of setae on opisthonotal shield, large size of idiosoma 540–575 μm 4

3. Opisthonotal gland gdZ1 (Po2) located anterolateral to seta Z1, setae Z3, S2–S4 short, do not reach beyond edge of opisthonotal shield.............................................................................. S. adelaidae sp. nov.

- Opisthonotal gland gdZ1 (Po2) located close to line connecting insertions of setae Z1 and Z2, setae Z3, S2–S4 long, reach beyond edge of opisthonotal shield........................................................ S. shoricus sp. nov.

4. J -series of opisthonotal shield with four pairs of setae, J3 lost; J4 and J5 microsetae, posterior pair of setae J5 do not reach posterior edge of opisthonotum......................................................... S. mariannae sp. nov.

- J -series of opisthonotal shield with four pairs of setae, J5 lost, setae J3 and J4 long, reach beyond the posterior edge ofopisthonotum......................................................................... S. ergaki sp. nov.

Distribution. Mites of new genus Sayanozercon are restricted in distribution to the Southern Siberia mountains in Russia. All five species of Sayanozercon inhabit middle and highlands in relict formation of mountain forest with Abies sibirica and Pinus sibirica . This ancient formation of taiga is considered as a derivative of tertiary nemoral “Turgai flora” by Krishtofovich (1946), widespread in the temperate zone of the Holarctic including South Siberia in Pliocene ( Kuminova, 1960, Ogureeva, 1980). Two species S. mariannae and S. adelaidae are known from Khamar-Daban Ridge in Baikal Region (Buryatia and Irkutskaya Oblast). Two species distributed in West Sayan Mountains: S. ergaki and S. mikhaili Two species are known from Gornaya Shoria mountain massif (Kemerovo Region): S. mikhaili and S. shoricus . A map of the distribution of Sayanazercon in different regions of South Siberia is presented in Fig. 62 View FIGURE 62 . Photos of localities in different regions of South Siberia mountains are shown in Figures 63–70 View FIGURE 63–70 .

Comparison with related genera (adults). Based on information about genera of Zerconidae in the world fauna, it can be stated that genera with combination of characters of new genus Sayanozercon have not yet been recorded. The presence of additional latero-ventral shield was previously noted in two genera Krantzas Błaszak and Rotundozercon Ujvári. Genus Krantzas ( U.S.A., Oregon) represented by one species K. mirificus Błaszak, 1981 , has a shortened latero-ventral shield located between peritrematal and ventrianal shields from setae s6 to R 6– R 7. Two species of genus Rotundozercon have been recorded in mountains of Southeast Asia: R. shuriken Ujvári, 2011 and R. jinggangshanensis Ma & Lin, 2014 . These two species represent latero-ventral shield reaching seta r4 anteriorly and different degrees of fusion shields at posterior edge: latero-ventral shield fused with ventrianal shield at level of setae R 4– R 5 in R. shuriken and long, fused at level of setae R 6– R 7 in R. jinggangshanensis . Shape of epistome of Sayanozercon is somewhat similar to Prozercon - type by Ujvári (2011b), to genera Echinozercon Błaszak and Bakeras Błaszak , but central process of epistome in designated genera lacks spines. The epistome of Sayanozercon is most similar to Blaszakiella Sikora & Skoracki. Only two species of Blaszakiella – B. mahunkai Ujvári, 2013 and B. luisiae Ujvári, 2013 ( Canada, British Columbia; U.S.A., state Washington) have an epistome with a central process with group of irregularly inserted spines. The location of gland gdZ1 anterolateral to seta Z 1 in four species of genus Sayanozercon ( S. mariannae S. adelaidae , S. ergaki , S. mikhaili ) is similar to representatives of the genus Blaszakiella – B. americana Sikora & Skoracki, 2008 ( U.S.A., Oregon) and subgenus Zercon (Zercorientalia) Ujvári with three species: Z. (Z.) formosianus Ujvári, 2011, Z. (Z.) spinosus Ujvári, 2011, Z. (Z.) sinensis Petrova & Taskaeva, 1968 from Southeast Asia. The dorsal chaetotaxy of Sayanozercon with all setae smooth and acicular is similar to the genera Monozercon Błaszak ( U.S.A., Oregon) and amphipalearctic genus Zerconella Willmann ( Willmann, 1953, Błaszak, 1984, Ujvári, 2010). Special characteristics of the genus Sayanozercon includes sexual dimorphism of chelicerae denticulation. Călugăr (2004 /2006) found that terminal part of fixed digit is bifurcated in males of Prozercon and Zercon species. This fact was supported in other genera of Zerconidae by Ujvári (2011b). Fixed digit of male chelicera of Sayanozercon has six teeth versus female with five teeth ( S. mariannae , S. ergaki , S. mikhaili , chelicerae of two other species were not dissected). Pilus dentilis is present on the fixed digit of chelicerae of Sayanozercon , but not observed in most genera of Zerconidae . Exceptions are the early derivate genera Halozercon and Baikalozercon ( Marchenko, 2018, 2019, 2021, 2022). The very interesting thing is strong sexual dimorphism emphasised in ventral chaetotaxy/porotaxy in Sayanozercon . The fibre brush structure in the inguinal region differs between males and females. Moreover, presence of fibre brush medial part in males (between left and right inguinal regions, not reported in females) could be related to the lack of setae st 5 in males (anterior to inguinal region); replacement of glands gv2 on soft cuticle at level of inguinal regions in females to ventrianal shield in males and lack of setae Zv 1 in males (gv 2 in males are placed antero-laterally to Jv1, more or less within the area usually occupied with Zv1. Postcoxal cuticular spines of inguinal region in genus Zercon were observed by Marquardt et al. (2024) with special study of Zercon hamaricus Kaczmarek et al. 2021 . Preliminary hypothesis of Marquardt et al. (2024) is what cuticular spines can be considered as protection the depressions at the posterior edges of coxae IV against fine soil particles that could limit or even block the leg movements. The most similar organs behind to coxae IV with deep depressions wich contains numerous cuticular spines were described by Hammen (1983) in Allothyridae , named peridium. The peridium is a peculiarity previously known among Allothyridae ( Holothyrida ) and Asternoseiidae ( Cercomegistina ) – early derivative taxa of Parasitiformes ( Walter, 2009; Lindquist et al. 2009). Its function is unknown. Alberty & Seeman (2004) concluded that peridium may serve to provide volatile substances, whereby the spines would increase the surface area from which these substances may be delivered. According to these authors spines are not likely to be the structures from which the secretion is extruded as Hammen (1989) suggested. According Walter (2009) the numerous integumental exocrine glands of Allothyridae probably are involved in production of a secretion that spreads over the cuticle via excavation canals. Order Holothyrida has a distribution largely confined to former Gondwanan landmasses (Travé, 1982), but family Zerconidae are common in Northern Hemisphere, occurring both in arctic latitudes and in highlands. There is no doubt that in all five known species of Sayanozercon the presence of large post-coxal poroids associated with the presence of a dense fibrous brush in the inguinal region. I suppose that inguinal glands produce a secretion and fibre brush function is to leave an odorous trace on the substrate. The presence of similar postcoxal structures with glands covered by cuticular spines in taxa that are distant both in systematic position and in type of geographical distribution would be interesting to study further.