Zetorchestes species

Kolesnikov, Vasiliy B. & Leonov, Vladislav D., 2021, Zetorchestes krisperi sp. nov. (Acari: Oribatida: Zetorchestidae) from Vietnam with juvenile morphology and identification key to known species of the genus, Zootaxa 5057 (4), pp. 545-561 : 558-560

Diagnostic key to adults of Zetorchestes species of the world

Based on the morphological features discussed above, we provide an identification key to the known species of Zetorchestes of the world that are sufficiently known. Omitted are Z. pacificus and Z. trituberculatus , as their original descriptions are poor, figures are absent, and type specimens are lost ( Krisper 1984b; Castagnoli & Pegazzano 1985). Zetorchestes equestris is based on redescription in Woolley (1957). Also, we do not recognize the subgenus Phyllorchestes , proposed by Mahunka (1983) with the following diagnosis: “similar to the genus Zetorchestes , but setae c 1 missing, thus, notogaster with 10 pairs of phylliform setae” (type species: Zetorchestes (Phyllorchestes) phylliferus Mahunka,1983 ). All combinations of these two features—presence vs. absence of c 1 and phylliform vs. setiform notogastral setae—can be found in Zetorchestes .

1 Notogastral setae (c, la, lm, lp, h 3, h 2) phylliform............................................................ 5

- Notogastral setae (c, la, lm, lp, h 3, h 2) setiform.............................................................. 2

2 Notogastral seta c present.............................................................................. 3

1

- Notogastral seta c 1 absent. Palaearctic.................................................. Z. falzonii Coggi, 1898 *

3 Trochanter IV with one seta............................................................................. 4

- Trochanter IV without setae; 11 pairs of notogastral, 2 pairs anal and 2 pairs adanal setae; anal region without wrinkles. Mediterranean..................................................................... Z. flabrarius Grandjean, 1951

4 One pair adanal setae; 10 pairs of notogastral setae (ps 3 or ps 2 absent); bothridial seta narrow. Europe................................................................................................ Z. grandjeani Krisper, 1987

- Two pairs of adanal setae; 11pairs notogastral setae (ps 3 and ps 2 present); bothridial seta broad. U.S.A., Oriental, China, Vietnam.......................................................................... Z. equestris Berlese, 1908 **

5 Notogastral seta c 1 present.............................................................................. 6

- Notogastral seta c 1 absent............................................................................... 8

6 Translamella present; entire epimeral region with polygonal reticulation. South Africa, Vietnam....................................................................................................... Z. ornatus Mahunka, 1985

- Translamella absent, epimeral region without polygonal reticulation or with only small areas having rounded cells........ 7

7 Lamella narrowing sharply in middle part, smooth; integument between genital and anal plates and between epimers I with rounded cells, one pair of adanal setae. Caucasus, Iran................. Z. reticulatus Karppinen et Poltavskaja, 1990 ***

- Lamella not narrowing sharply in middle part, irregular; integument between genital and anal plates and between epimers I without rounded cells, two pairs of adanal setae. Mediterranean..................... Z. phyllosetus Mahunka, 1977 ****

8 Lamellar surface is smooth; prolamella absent; notogastral setae is narrow phylliform (width 2–3)..................... 9

- Lamellar surface is irregular; prolamella present; notogastral setae is wide phylliform (width 5–12)................... 10

9 Epimeral region with reticulation; medial pore present; rostral tubercles widely spaced, distance between them more than half tubercle width; dorsosejugal suture distinct. South Africa, Vietnam...................... Z. transvaalensis Coetzee, 1989

- Epimeral region without reticulation, medial pore absent; rostral tubercles broad, distance between them noticeably less than half tubercle width; dorsosejugal suture partially visible; Neotropical, Canary Island; Vietnam.... Z. schusteri Krisper, 1984

10 Rostral tubercles widely spaced, distance between them more than half tubercle width.............................. 11

- Rostral tubercles broad, distance between them noticeably less than half tubercle width............................. 14

11 Dorsosejugal suture distinct; ps setae thin................................................................. 12

- Dorsosejugal suture not visible, represented by only row if granules; ps setae phylliform............................ 13

12 Median pore of notogaster absent; interlamellar and notogastral setae wide (9–12); shoulder apophysis absent. New Guinea............................................................................ Z. novaguineanus Krisper, 1987

- Median pore of notogaster present, interlamellar and notogastral setae narrower (5–7); shoulder apophysis present. Madagascar, Tanzania, Vietnam.......................................................... Z. phylliferus Mahunka, 1983

13 Two pairs of anal and adanal setae; 10 pairs of notogastral setae (h 1 present); interlamellar setae do not touch distally; seta la displaced laterally (variable). Oriental, Vietnam, Ceylon............ Z. saltator Oudemans, 1915 (see commentary below)

- One pair of anal and adanal setae; 9 pairs of notogastral setae (h 1 absent); interlamellar setae touch distally; setae la not displaced laterally........................................................................ Z. krisperi sp. nov.

14 Seta h 1 present; prodorsum and median part of notogaster without wrinkles. New Guinea.. Z. vanderhammeni Krisper, 1987

- Seta h 1 absent; prodorsum and median part of notogaster with wrinkles. Japan, New Guinea, Oriental..................................................................................................... Z. aokii Krisper, 1987

Notes:

*—the relationship of Z. micronychus and Z. falzonii has not been resolved yet. In this key, we consider Z. micronychus as a nomen dubium, following Krisper (1984a);

**—distribution records are suspicious since Z. equestris is not sufficiently described;

***—the number of adanal setae was not noted in the text of the description, but on figs 3B, C (Karppiner & Poltavskaja1990) only one pair is seen;

****— Mahunka (1977) noted “2(?) pairs of adanal hairs present”—but the meaning of the question-mark was not explained.

Tseng (1982) and Choi (1988) described some species as Z. saltator from Taiwan ( Tseng 1982) and the Korean Peninsula ( Choi 1988), but these works are problematic. Tseng (1982) illustrated a specimen with long and phylliform notogastral (6 pairs according to the figure) and interlamellar setae, one pair of thin notogastral setae (wide spread), two pairs of anal and adanal setae (the figured position of adanal setae is unusual for Zetorchestes and we suggest was sketchily shown), wide spread rostral tubercles, incomplete dorsosejugal suture, «with 2 median concaved sclerotes» and row of granules. Meaning of «with 2 median concaved sclerotes» is vague, probably dorsosejugal suture interrupted in the middle is implied. The number of notogastral setae is unclear: 7 pairs are noted in the text but in the posterior part of notogaster 2 pairs of alveoli are also depicted, but not described. Thus, there are few options for Tseng’s species: 1) 9 pairs of notogastral setae (phylliform c 2, la, lm, lp, h 3, h 2, spread wide thin ps 1, ps 2 and ps 3 —alveoli); or 2) developed notogastral setae are more than 9 (not all are shown). The last set of features partially matches the description of Z. saltator (excepting dorsosejugal suture). The first set does not correspond to any known Zetorchestes species. The description of Z. saltator by Choi (1988) is less detailed: 5 phylliform and two thin notogastral setae, phylliform interlamellar setae, rostral tubercles spread wide, one pair of anal setae, dorsosejugal suture incomplete. The full number of notogastral setae was not reported (but ps 2 and ps 3 are absent). The term “thin setae” is rather vague. The number of adanal setae is not given. Cuticular sculpturing and cerotegument are not shown or described. Only by the noted number of anal setae can we clearly conclude that Choi’s species is not Z. saltator . Both discussed descriptions are insufficient for identification, and these mites could represent Z. saltator (Tseng’s species), Z. krisperi sp. nov. (Choi’s species) or some new species.

Note on juvenile characters

Ermilov & Kolesnikov (2013) provided diagnoses for the juvenile stages of Zetorchestes . Now, we can amend this diagnosis based on the new details found for the tritonymph of Z. krisperi sp. nov.

Integument of gastronotum with granular (forming polygonal pattern or not) or wrinkled cerotegument; rostral setae thickened and bifurcated distally; bothridial seta club-shaped, pubescent; with 7–9 pairs of gastronotal setae (c 1 and h 1 present or absent); trochanters III and IV and all femora with dentate ventral carina; legs IV of jumping type; all claws well-developed, simple (unmodified); respiratory channels present in epimeral and genital areas.