Pachyseius Berlese 1910
Creators: name: Mašán, Peter
name: Mihál, Ivan
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Mesostigmata
Pachylaelapidae
Pachyseius

description: Genus Pachyseius Berlese, 1910
Diagnosis
Dorsal idiosoma. Dorsoventrally flattened, oval to oblong short-legged forms with a holodorsal shield. Dorsal shield bearing 30 pairs of setae; all dorsal setae usually uniformly formed, simple and needle-like. Bases of dorsal setae J1 adjacent and situated paraxial to setae J2. Infundibulum of glands gdj3 (also gdZ1 and gdS4) sometimes conspicuously enlarged (hypertrophied), cavity-like and strongly sclerotized. Dorsum usually with reticulate sculptural pattern.
Ventral idiosoma. Presternal shields often present. Sternal shield free and mostly with 3 pairs of setae and 2 pairs of pores. A pair of small rounded metasternal shields with a seta and pore present (in P. morazae sp. nov., metasternals fused to sternal shield). Genital shield separate, truncate posteriorly, and with 4 oval sclerites close to its posterior margin. Genital pores on or off genital shield. Large ventri-anal shield with 2–4 preanal and 3 circumanal setae present, adanal setae anterior to anus. Peritremes, peritrematal and podal shields relatively well developed. Posterior section of peritrematal shield slightly widened, abutting the exopodal shields, and not extending conspicuously beyond coxa IV. In some species (described in this paper), posterior tip of peritrematal shield fused to exopodal shield IV. Area between peritrematal shield and anterolateral corner of ventri-anal shield often with 1–3 tiny sclerites. Male with separate sterniti-genital and ventri-anal shields. In female, a pair of distinctive, narrow and elongated metapodal shields present (rarely metapodals fused to ventri-anal shield); lateral and opisthogastric cuticle usually with 6–12 pairs of setae.
Gnathosoma. Hypostome relatively narrow; corniculi short and horn-like. Male palptibia without outgrowths. Palp apotele 3-tined. Epistome simple, subtriangular and with serrated lateral margins, apex pointed, truncate or widely rounded. Cheliceral spermatodactyl in male subdistal, elongated, slightly longer than movable digit, curved backward, tubular, progressively tapered distally and truncate apically. Female cheliceral digits relatively slender, movable digit bidentate, fixed digit usually with 2–4 small teeth.
Spermathecal apparatus. Sperm access system tubular and associated with posterior margin of coxae III. Spermathecal tubes very long, tenuous and with slightly broadened tips.
Legs. Legs normal, shorter than idiosoma. Tarsi with ambulacrum and 2 claws, tarsus II with 1–3 spur-like distal setae. Male femur II and tibia II spurred. Typical chaetotaxy as follows: coxa I–IV: 2, 2, 2, 1; trochanter I–IV: 6, 5, 5, 5; femur I–IV: 13 (2-5/4-2), 11 (2-5/3-1), 6 (1-3/1-1), 6 (1-3/1-1); genu I–IV: 12 (2-5/3-2), 11 (2- 5/2-2), 8 (2-4/1-1), 8 (2-4/1-1); tibia I–IV: 12 (2-5/3-2), 10 (2-4/2-2), 7 (1-3/2-1), 7 (1-3/2-1); tarsus II–IV: 18 (3-7/5-3), 18 (3-7/5-3), 18 (3-7/5-3). The following variations occur in the chaetotaxy of some leg segments: in P. iraola, femur I and genu II with 12 setae (2-5/3-2); in species related to P. humeralis, tarsus IV with 17 setae (3-6/5-3).
Key to the females for the world species of the genus Pachyseius 1)
1. Ventri-anal shield with 4 pairs of pre-anal setae; anterior margin of sternal shield with one pair of strongly sclerotized and horn-like projections; length of dorsal shield 640–650 µm P. sinicus Yin, Lü & Lan, 1986
- Ventri-anal shield with at most 3 pairs of pre-anal setae; sternal shield smooth and without horn-like projections on anterior margin............................................................. 2
2. Ventri-anal shield with 3 pairs of pre-anal setae............................................. 3
- Ventri-anal shield with 2 pairs of pre-anal setae............................................. 7
3. Posterior section of peritrematal shield and exopodal shield IV fused............................ 4
- Posterior section of peritrematal shield and exopodal shield IV not fused......................... 5
4. Metapodal shields greatly expanded, subtriangular, very large and with reticulate-punctate sculpture; presternal shields absent; exopodal shields III and IV well separated; length of dorsal shield 565–575 µm............................................................. P. pachylaelapoides sp. nov.
- Metapodal shields normal in size, narrow and elongated; presternal shields well developed and sclerotized; exopodal shields III and IV abutting each other; length of dorsal shield 523 µm... P. cicaki sp. nov.
5. Presternal shields absent; peritrematal shield (close to stigma) anterior margin of dorsal shield (between setae z1 and z2) with normal pores; dorsal setae modified, spatulate; femur I and genu II with 12 setae (2- 5/3-2), tarsus IV with 18 setae (3-7/5-3); lateral and ventral soft cuticle with 12–13 pairs of setae; length of dorsal shield 805 µm............................................... P. iraola Moraza, 1993
- Presternal shields weakly sclerotized, with fine net-like ornamentation, and connected with anterior margin of sternal shield; peritrematal shield (close to stigma) anterior margin of dorsal shield (between setae z1 and z2) with hypertrophied poroid structure; dorsal setae simple, needle-like; femur I with 13 setae (2- 5/4-2), genu II with 11 setae (2-5/2-2), tarsus IV with 17 setae (3-6/5-3); lateral and ventral soft cuticle with 8–9 pairs of setae................................................................. 6
6. Ventri-anal shield enlarged laterally (width: 255–300 µm), subequal in length and width (length/width: 0.96–1.07); metapodal shield closely abutting lateral margin of ventri-anal shield; lateral and ventral soft cuticle with 9 pairs of setae; length of dorsal shield 640–760 µm..... P. wideventris Afifi & Nasr, 1984
- Ventri-anal shield oblong (not exceeding 240 µm in width), longer than wide (width: 165–235 µm, length/ width: 1.08–1.28); metapodal shield and lateral margin of ventri-anal shield well separated; lateral and ventral soft cuticle with 8 pairs of setae; length of dorsal shield 530–665 µm.. P. humeralis Berlese, 1910
7. Separate metapodal shields absent (metapodals fully fused with anterolateral margins of ventri-anal shield); marginal region of dorsal shield with 3 pairs of hypertrophied poroid structures; length of dorsal shield 600–715 µm........................................... P. strandtmanni Solomon, 1982
- Separate metapodal shields present; marginal region of dorsal shield with at most one pair of hypertrophied poroid structures (between setae z1 and z2)........................................... 8
8. Metasternal shields fully fused with sternal shield; peritrematal shield and exopodal IV fused; peritrematal shield posteriorly expanded, truncate and abutting anterolateral margin of ventri-anal shield; length of dorsal shield 790–845 µm............................................... P. morazae sp. nov.
- Metasternals and exopodals IV free; posterior tip of peritrematal shields tapered, obtusely pointed or rounded, and well separated from anterolateral margins of ventri-anal shield...................... 9
9. A pair of presternal shields well developed and sclerotized; metapodal shields closely abutting anterolateral margins of ventri-anal shield; ventri-anal shield subpentagonal, subequal in length and width, and with small pore close to anterolateral margins; length of dorsal shield 560–608 µm................................................................................ P. orientalis Nikolsky, 1982
1. Pachyseius chenpengi MA & YIN, 2000 is not included in the key due to inadequate original description and differential diagnosis.
- Presternal shields absent; metapodal shields and anterolateral margins of ventri-anal shield well separated by wide strip of soft cuticle; ventri-anal shield narrow, elongated, distinctly longer than wide, and without pores close to anterolateral margins...................................................... 10
10. Posterior tip of peritrematal shields reaching the posterior margin of exopodals IV (both with position beyond posterior margin of coxae IV); exopodal shields III and IV abutting each other............. 11
- Posterior tip of peritrematal shields not reaching the posterior margin of exopodals IV as well as posterior margin of coxae IV (posterior margin of exopodals IV exceeding the posterior margin of coxae IV); exopodal shields III and IV not abutting each other, separated by inner projection of peritrematal shield................................................................................... 12
11. Dorsal setae relatively longer (e.g. setae J4 with tip reaching beyond the following setae J5 as well as posterior margin of dorsal shield) and with spatulate tips................. P. cavernicola Ishikawa, 1989
- Dorsal setae relatively shorter (setae J4 with tip not exceeding beyond the posterior margin of dorsal shield and only barely reaching to the following setae J5), simple and needle-like; length of dorsal shield 512–600 µm....................................................... P. angustus Hyatt, 1956
12. Ventri-anal shield oblong, with almost parallel lateral margins, slightly wider in the anterior part; length of dorsal shield 821 µm............................................... P. morenoi Moraza, 1993
- Ventri-anal shield suboval, widest in its middle part; length of dorsal shield 750 µm.......................................................................... P. angustiventris Willmann, 1935
description: Published as part of Mašán, Peter & Mihál, Ivan, 2007, New mites of the genus Pachyseius Berlese from Bulgaria (Acari: Pachylaelapidae), pp. 59-68 in Zootaxa 1485 on pages 60-62, DOI: 10.5281/zenodo.176951