The Chernetidae is the most speciose family in the Pseudoscorpiones and is composed of over 650 species in more than 110 genera, but only 10 genera and 16 species have been reported from China. The chernetid genus Dendrochernes was erected by Max Beier in 1932, and at present comprises only four known species: the type species Dendrochernes cyrneus is widespread in central Asia (Pakistan, Kazakhstan and Kyrgyzstan), north Africa and Europe; while the remaining three species occur in north America: Dendrochernes crassus, Dendrochernes morosus, and Dendrochernes instabilis.
In a paper published in the journal Arthropoda Selecta on 19 June 2020, Zhizhong Gao of the Department of Biology and Wutai Mountain Institute of Resource and Environment at Xinzhou Teachers University, and Feng Zhang of the Key Laboratory of Zoological Systematics and Application at Hebei University, describe a new species of Dendrochernes from Xinjiang Province, China.
Kanas Lake, located in a valley in the Altai Mountains in the Burqin County of Altay Prefecture, northwestern China, is China’s deepest freshwater alpine lake, with a high biodiversity. It borders with the country of Kazakhstan, Mongolia and Russia.
While examining Pseudoscorpion specimens collected from Xinjiang, two chernetid specimens presenting the generic characters of Dendrochernes were examined: eye spots lacking or indistinct; tergites divided except the last one and finely to moderately granulate; setae of body and palps broadened and thickened, denticulate and short, never strongly clavate; rallum with 4 (but occasionally 3) blades; palps stout, finely to moderately granulate; accessory teeth of chelal fingers numerous; tactile seta sub-terminal of movable finger nearer to sub-basal than to terminal; fixed finger with tactile seta interior sub-terminal at the level of or very little distal to the level of exterior sub-terminal; tarsus IV with a tactile seta located distal to the midpoint of the tarsus, being 0.6 to 0.7 of the length of the tarsus from the proximal margin of the segment; the spermatheca of the female with two long, slender tubules, of uniform diameter throughout, greatly coiled, and without a terminal enlargement or bulb.
The new species is named Dendrochernes mahnerti, in honour of Volker Mahnert, a famous zoologist and arachnologist, who has made significant contribution and leaves behind an outstanding scientific legacy on Pseudoscorpions. It is described from two female specimens, collected by Feng Zheng in August 2006 from under tree bark, at an altitude of 1456 m above sealevel, in the Kanas National Nature Reserve in Burqin County in the Xinjiang Uygur Autonomous Region of China.
The colour of Dendrochernes mahnerti is mostly reddish brown, carapace, legs brown, tergites and palps darker, remaining parts (sternites and pleural membranes) light yellowish brown. Most setae slightly apically denticulate.
The surface of the carapace is evenly granular. Slightly longer than broad (1.07–1.17 times), eyespots indistinct, with two regularly granular transverse furrows, both of them very distinct, the subbasal one slightly nearer to the posterior margin than to median furrow, a longitudinal shallow groove in metazone. With about 110 setae, including 6 on anterior margin and 12–13 on posterior margin. All setae short and apically dentate.
All tergites of the abdomen are widely divided except the last one. Lateral keels absent; weakly scale-shaped sculpture. Half-tergites with about 8–11 setae, tergite VI with 13–16 setae (include 2 long tactile setae), anus with 2 simple and acuminate setae. Manducatory process with 5 setae. All sternites distinctly divided except VI, weakly scaly sculptured, setae simple and acuminate, chaetotaxy (IV–XI): 6(5)–6: 13–13(16): 15(16)–15: 14(17)–14(15): 11(15)–12(15): 11(15)–11(16): 9(11)–10(11): 12 (include 4 long tactile setae): 2 (simple and acuminate setae). Coxae of pedipalps scale-shaped sculpture, with about 21, coxae I with about 15, II 20, III about 25 setae, IV numerous setae. Anterior genital operculum with about 31–32 simple and acuminate setae, 21–22 setae in a row along the posterior margin of the posterior operculum.
Spermatheca with 2 long tubules, both of them without distinct terminal enlargements or bulbs.
The chelicera have weakly scale-shaped sculpture. Five setae in basal part, all of them simple and acuminate; with 2 lyrifissures on the dorsal face of palm; fixed fingers with a few different sized teeth in the end. Movable finger with a seta in midway of terminal of finger; serrula exterior with 23–24 lamellae. Rallum usually with 4 blades, but occasionally with 3, anterior blade slightly denticulate. Galea with 6 short branches.
Palp slender, most segments normally granulate; except for chelal fingers, which are finely gaping; setae acuminate and weakly apically dentate; without tactile setae on femur, patella or hand; trochanter with distinct rounded dorsal hump; proportions (based on two specimens): trochanter 1.41–1.70 times as long as broad; femur 2.63–2.71 times as long as broad; patella 2.18–2.23 times as long as broad; chela with pedicel 2.63–2.75 times as long as broad, chela without pedicel 2.45–2.54 times as long as broad, hand with pedicel 1.56–1.59 times, without pedicel 1.37–1.41 times, as long as broad. Movable finger 0.77–0.78 times as long as hand with pedicel, and 0.88 times without pedicel. fixed finger with 36–37 teeth, 11–12 acuminate accessory teeth on lateral side, 7–8 accessory teeth on interior side; movable finger with 40–44 teeth, 10–11 acuminate accessory teeth on lateral side, 6–7 accessory teeth on interior side; nodus ramosus closer to terminal than to sub-terminal.
Venom apparatus only present in moveable chelal fingers, venom duct slender, extend over trichobothrium terminal in movable fingers.
Leg I has a typical facies, with numerous terminal slightly denticulate and acuminate setae, tactile setae absent, weakly scale-like sculpture, claws simple; proportions: trochanter 1.00–1.31 times; femur 1.45–1.47 times; patella 2.30–2.35 times; tibia 3.43–3.54 times; tarsus 4.20–4.56 times as long as deep. Subterminal tarsal seta simple, acuminate and curved, arolium shorter than claws.
Leg IV has a surface weakly scale-like sculptured; tibia and tarsus with numerous terminal slightly denticulate and acuminate setae, trochanter 1.68–1.71 times; femur+patella 3.23–3.48 times; tibia 4.44–4.53 times; tarsus 3.75–3.83 times as long as deep. An acute tactile seta in terminal third of tarsus and almost the half long as tarsus; arolia undivided and shorter than the simple and large claws, subterminal seta simple, acuminate and curved.
Both chelicerae of the holotype and paratype were examined in different orientations to obtain an 'all-round-view' of each rallum. Although most had four blades, which is typical of the genus, the left rallum of the holotype consisted of only three blades.
The right tubule of the spermatheca in the holotype possesses a short branch, which is unusual, we subsequently dissected the spermatheca of the paratype and there is no any modification on both tubules, so Gao and Zhang prefer to think that the presence of a short branch on the right spermatheca of the holotype is an anomaly.
Dendrochernes cyrneus is widespread across Europe and Asia, with vast literatures citations. It is difficult to identify a specimen to species level only based on immature individuals which little diagnostic characteristic can be used, for instance, extraordinarily dark coloring of the carapace, the palps and the tergites is absent in juveniles. The record from Kyrgyzstan are based on only a deutonymph; although it is possible that Dendrochernes cyrneus distributed in Kyrgyzstan, the record is still unreliable.
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