Sperchon, Kramer, 1877

Kolesnikov, Vasiliy B. & Stolbov, Vitaly A., 2025, Review of the genus Sperchon Kramer, 1877 (Acari, Hydrachnidia: Sperchontidae) from Russia, Zootaxa 5666 (1), pp. 53-73 : 69-70

Key to species of the Sperchon from Russia

1 P-4 with two greatly enlarged ventral peg-like setae, close to each other ( Palpisperchon Lundblad, 1941 ).............. 26

– P-4 with two small ventral peg-like setae................................................................... 2

2 Integument rugose or papillate ( Sperchon s. str.)............................................................. 3

– Integument reticulated (at least in localized areas) ( Hispidosperchon Thor, 1901 ).................................. 28

3 Claws of leg with 3 teeth; P-4 shorter than P-3.............................................................. 4

– Claws of leg with 2 teeth; P-4 longer than P-3............................................................... 5

4 Integument with muscle attachment sclerites; P-2 with 2 setae; P-3 is stockier, maximum height near middle of segment; leg claws with three unequal clawlets, lamella ventral margin concave......................... Sperchon (Sperchon) pesici

– Integument without muscle attachment sclerites; P-2 with 3 setae; P-3 more slender, maximum height in proximal quarter; leg claws with three subequal clawlets, lamella ventral margin straight..................... Sperchon (Sperchon) tridentatus

5 Acetabula small, rounded, distance between Ac-1 and Ac-2 is more than 3 times longer than the length of each acetabulum. 6

– Acetabula larger, rounded or elongated, distance between Ac-1 and Ac-2 is no more than 3 times longer than the length of each acetabulum.......................................................................................... 9

6 P-3 with setae on ventral side............................................................................ 7

– P-3 without setae on ventral side......................................................................... 8

7 Integument with large tubercles into which cuticular folds flow; P-2 with short conical ventrodistal process; P-4 with ventral peg-like setae of different size - distal seta is noticeably smaller than proxima setal; P-5 with 3 filiform setae (except bifurcated seta); length of genital plates female 285, male—265................................. Sperchon (Sperchon) prosperus

– Integument with small tubercles and ribs, without folds; P-2 with long conical ventrodistal process; P-5 with 4 filiform setae (except bifurcated seta); length of genital plates female 250–270, male—195–230........ Sperchon (Sperchon) prosperoides

8 P-5 short, length is approximately equal to its width; rostrum longer................... Sperchon (Sperchon) minutiporus

– P-5 longer, twice as long as it is wide; rostrum shorter............................... Sperchon (Sperchon) laurenticus

9 Acetabula Ac-1 and Ac-2 slightly elongated, not more than two times longer than their width........................ 10

– Acetabula Ac-1 and Ac-2 noticeably elongated, their length is more than two times longer than their width............. 16

10 Base of ventrodistal process on P-2 without spine-like seta.................... Sperchon (Hispidosperchon) kurilensis *

– Base of ventrodistal process on P-2 with 1 spine-like seta.................................................... 11

11 P-4 with one ventral peg-like seta............................................. Sperchon (Sperchon) monodentatus

– P-4 with two ventral peg-like setae...................................................................... 12

12 Length of P-5 longer than distance from distal ventral peg-like seta on P-4 to distal margin of P-4; distance between bases of distal and ventral filiform setae exceeds length of ventral setae................................................ 13

– Length of P-5 shorter than or approximately equal to distance from distal ventral peg-like seta on P-4 to distal margin of P-4; distance between bases of distal and ventral filiform setae shorter than length of ventral setae........................ 15

13 Integument with numerous rounded papillae connected to each other by short skin folds; ventral filiform seta on P-5 short. 14

– Integument with linear wavy folds, without rounded papillae; ventral filiform seta on P-5 of medium length............................................................................................ Sperchon (Sperchon) similis

14 P-4 longer than P-2+3; ventrodistal process on P-2 with 2 setae, clearly bifurcated........... Sperchon (Sperchon) questor

– P-4 not longer than P-2+3; ventrodistal process on P-2 with 3 setae, not bifurcated... Sperchon (Sperchon) uralensis sp. nov.

15 Length of P-5 shorter than distance of distal ventral peg-like seta on P-4 to distal margin of P-4; acetabula large, distance between Ac-1 and Ac-2 is 1/2 times less than their length; ridges of integument on dorsum and posterior to genital field are arranged in irregular rows; excretory pore without sclerotized ring...................... Sperchon (Sperchon) fluviatilis

– Length of P-5 approximately equal to distance of distal ventral peg-like seta on P-4 to distal edge of P-4; acetabula smaller, distance between Ac-1 and Ac-2 is 1-2 times greater than their length; ridges of idosoma covers on dosrum and posterior to genital opening are arranged in transverse rows; ecxretory pore with sclerotized ring................................................................................................ Sperchon (Sperchon) zhavoronkovae sp. nov.

16 Base of ventrodistal extension on P-2 with 2 spine-like setae, tip of ventrodistal extension with 1 seta............................................................................... Sperchon (Sperchon) monticolus Wainstein, 1981

– Base of ventrodistal extyension on P-2 with 1 spine-like seta or without spine-like seta, tip of ventrodistal process with 2-3 seta............................................................................................... 17

17 Base of ventrodistal process on P-2 without spine-like seta................................................... 18

– Base of ventrodistal process on P-2 with 1 spine-like seta.................................................... 20

18 Ventrodistal extension on P-2 long; P-2 and P-3 not shortened or widened; ventral peg-like setae on P-4 not close to each other, directed ventrally............................................................ Sperchon (Sperchon) squamosus

– Ventrodistal extension on P-2 short; P-2 and P-3 are greatly shortened and widened; ventral peg-like setae on P-4 closer to each other, directed proximally.............................................................................. 19

19 Р-2 higher than long, its distoventral projection narrow, finger-shaped; Р-4 distoventral peg-like seta located medially, closer to proximoventral peg seta than to distal segment margin................................. Sperchon (Sperchon) turgidus

– Р-2 as long as high, its distoventral projection short, forming а broad-based triangle; Р-4 distoventral peg-like seta located ventrally, closer to distal segment margin than to proximoventral peg seta................. Sperchon (Sperchon) resupinus

20 Ventrodistal extension on P-2 short, ventral spine seta longer that its length...................................... 21

– Ventrodistal extension on P-2 long, ventral spine seta not longer that its length.................................... 22

21 P-5 twice as long as wide, medial seta is located almost at same level as bifurcated seta; ventral peg-like setae on P-4 pointed, proximal peg-like seta situated near middle of ventral row P-4......................... Sperchon (Sperchon) ussuriensis

– P-5 2.5 times longer than wide, medial seta distinctly posterior to bifurcated seta; ventral peg-like setae on P-4 with flat tip, proximal peg-like seta does not reach 1/2 middle of ventral row P-4..................... Sperchon (Sperchon) kuluensis

22 Cx-I medially fused, completely surrounding gnathosomal base; ventral peg-like setae on P-4 very small; P-4 longer than P- 2+3....................................................................... Sperchon (Sperchon) brevirostris

– Cx-I medially separated bу а fine strip of membranous integument; ventral peg-like setae on P-4 of normal size; P-4 not longer than P-2+3......................................................................................... 23

23 Plate with postocular seta greater than ocular capsule............................... Sperchon (Sperchon) glandulosus

– Plate with postocular seta smaller than ocular capsule....................................................... 24

24 Anus surrounded bу а sclerotized ring................................................................... 25

– Anus without sclerotized ring................................................. Sperchon (Sperchon) thienemanni

25 Seta Dgl-1 longer than diameter its chitinous plate; P-1 without seta; 17-19 medial genital setae in female; dorsal and ventral setae on tibia IV are indistinguishable from each other….............................. Sperchon (Sperchon) orientalis

– Seta Dgl-1 shorter than diameter its chitinous plate; P-1 with seta; 12 medial genital setae in female; dorsal setae on tibia IV slightly thinner and longer than ventral setae......................................... Sperchon (Sperchon) termalis

26 Integument with small papillae; ventral extension on P-3 is weakly expressed; acetabula Ac-1 and Ac-2 are elongated, their length is greater than distance between the acetabula........................... Sperchon (Palpisperchon) crassipalpis

– Integument fine lined or with strips and ribs; ventral protrusion on P-3 is distinct; acetabula Ac-1 and Ac-2 are rounded, their length is clearly less than distance between the acetabula..................................................... 27

27 Integument fine-lined; Cx-II and Cx-III close together, the distance less than their width; ventral peg-like seta on P-4 not expanded or slightly expanded at tip, not rhomboid................................ Sperchon (Palpisperchon) distans

– Integument with strips and ribs; Cx-II and Cx-III not close together, distance is greater than their width; ventral peg-like seta on P-4 weakly expanded at tip, rhomboid....................................... Sperchon (Palpisperchon) scopetsi

28 Well developed sexual dimorphism: mаles раlр stout, with inflated Р-2 and Р-3 distal margins forming strongly developed sheaths flanking base of subsequent segments, female раlр slender, ventral margin of Р-3 covered bу fine denticulation.......................................................... Sperchon (Hispidosperchon) denticulatus species group**

– Poorly developed sexual dimorphism, in both sexes, palp neither inflated, nor with а denticulate ventral margin of Р-3.... 29

29 Сх-III with а glandularium near medial margin............................................................. 30

– Сх-III without a glandularium near medial margin.......................................................... 33

30 Distance between Ac-1 and Ac-2 is shorter than their length.................................................. 31

– Distance between Ac-1 and Ac-2 is longer or approximately equal to their length… Sperchon (Hispidosperchon) levanidovae

31 Excretory pore located closer to Vgl-1 than to Vgl-3; male with 2 large dorsal shields. Sperchon (Hispidosperchon) nevelskoii

– xcretory pore located closer to Vgl-3 than to Vgl-1; male with 1 large dorsal shield or with several isolated plates........ 32

32 Excretory pore surrounded bу а sclerotized ring; IV-leg with densely plumose dorsal setae (> 6); in both sexes, dorsum with several isolated platelets................................................ Sperchon (Hispidosperchon) hispidus ***

– Excretory pore without sclerotized ring; IV-leg with less plumose dorsal setae (<6); males with а dorsal shield, females with several isolated plates.................................................... Sperchon (Hyspidosperchon) clupeifer

33 Р-3 without ventral setae............................................... Sperchon (Hispidosperchon) compactilis

– Р-3 with ventral setae................................................................................. 34

34 Р-3 with up to 2 ventral setae; integument sculpture made up of а network of fine denticles combined with additional larger papillae.............................................................. Sperchon (Hispidosperchon) papillosus

– Р-3 with four, rarely three ventral setae; integument sculpture formed exclusively bу fine denticles............... Sperchon (Hispidosperchon) setiger