Review of the ant genus Anochetus Mayr , 1861 ( Hymenoptera , Formicidae ) from China , with revival of the valid status of Anochetus gracilis

Eight species of the ant genus Anochetus are recognized in China: A. graeffei Mayr, A. lanyuensis Leong et al., A. longus sp. n., A. madaraszi Mayr, A. mixtus Radchenko, A. medogensis sp. n., A. risii Forel, A. subcoecus Forel. A. taiwaniensis Terayama, 1989 is proposed as a junior synonym of A. risii Forel, 1900. Anochetus gracilis Karavaiev, 1925 is restored from synonymy of A. risii. A key based on the worker caste is provided for the Chinese species.


Introduction
The genus Anochetus belongs to the tribe Ponerini, and constitutes as the sister group to Odontomachus (Bolton 2018, Schmidt 2013).A total of 113 extant species and 8 fossil ones have so far been known in the world (Bolton 2018), and the genus is especially species-rich in the tropical and subtropical regions, except for a few species extending into temperate areas (Brown 1978).The first comprehensive revision of the genus was provided by Brown (1978), in which 12 new species were described, one genus-level and 38 species-level synonyms were solved, and 22 species groups were proposed.After his outstanding work, a series of studies further contributed to our understanding of the genus Anochetus and especially in the last decade.Eight fossil species are described from Dominican (Baroni Urbani 1980, De Andrade 1994, Mackay 1991).Twenty-eight species are described from five zoogeographic regions: eleven in the Malagasy Region (Fisher andSmith 2008, Shattuck andSlipinska 2012), four in the Neotropical Region (Lattke 1987, González-Campero and Elizalde 2008, Feitosa et al. 2012), three in the Palaearctic Region (Terayama 1996, Kugler and Ionescu 2007, Sharaf et al. 2017), and five from the Indo-Australian Region and Oriental Region (Terayama 1989, Nuril Aida and Idris 2011, Zettel 2012, Bharti and Wachkoo 2013, Marathe and Priyadarsanan 2016, Leong et al. 2018), respectively. Besides, A. ruginotus Stitz, 1925 was revived from synonymy of A. graeffei Mayr, 1870by Zettel (2012), and A. yunnanensis Wang, 1993 was proposed as junior synonym with A. mixtus Radchenko, 1993by Satria et al. (2017).
In this paper, two new species are described, Anochetus longus sp.n. and A. medogensis sp.n., while A. madaraszi is newly recorded from China.Anochetus taiwaniensis Terayama, 1989 is proposed as a junior synonym of A. risii Forel, 1900, whereas A. gracilis Karavaiev, 1925 is revived from synonymy of A. risii.A key to Chinese species based on the worker caste is also provided.

Materials and methods
The holotypes, paratypes and all non-type specimens examined are deposited or will be deposited in the following institutions.
Images of the type specimens available on the AntWeb (http:// www.antweb.org)were examined.The specimens are examined with a Leica M205A stereomicroscope.
High-quality multifocused montage images were produced with Leica DFC 450 digital imaging system and Leica Application Suite V4.3 software.All measurements are given in millimeters.Standard measurements and indices are mostly as defined by Bolton (1975).

DPW
Maximum width of petiole in dorsal view.

ED
Maximum diameter of eye.

HL
Straight-line length of head in perfect full-face view, measured from the mid-point of the anterior clypeal margin to the midpoint of the posterior margin.In species where one or both of these margins are concave, the measurement is taken from the mid-point of a transverse line that spans the apices of the projecting portions.

HW
Maximum width of head in full-face view, excluding the eyes.

MSL
Diagonal length of the mesosoma in lateral view, measured from the point at which the pronotum meets the cervical shield to the posterior basal angle of the metapleuron.

PH
Height of petiole measured in lateral view from the apex of the ventral (subpetiolar) process vertically to a line intersecting the dorsalmost point of the node.

PL
Length of petiole measured in lateral view from the anterior process to the posteriormost point of the tergite, where it surrounds the gastral articulation.

PW
Maximum width of pronotum measured in dorsal view.

SL
Straight-line length of the antennal scape, excluding the basal constriction or neck.

TL
Total outstretched length of the individual, from the mandibular apex to the gastral apex.The maximum diameter of eye narrower than the width of scape at it midlength (Fig. 10A); the junction between propodeal dorsum and declivity forming a pair of denticles laterally (Fig. 10D); pronotum smooth and shining (Fig. 10C In full-face view head longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin without denticles; apical portion with three distinct teeth.Antennae 12-segmented; scapes just reaching to posterior corners of head.Eyes moderate-size, maximum diameter equal to the width of mandible at its base.

Key to Chinese species of
In lateral view mesosoma stout, dorsal outline of pronotum convex and gradually sloping anteriorly.Promesonotal suture indistinct dorsally and laterally.Dorsal outline of mesonotum and propodeum almost straight, posterolateral corners of propodeum forming obtuse triangle.Metanotal groove broadly impressed.Petiole thin, distinctly higher than long, narrowing dorsally, anterior margin straight, posterior margin distinctly convex; subpetiolar process developed, anterior margin straight, posteroventral margin rounded.Dorsal margin of petiole weakly convex in anterior view.
Frons and anterior part of vertex longitudinally striate; remainder of head smooth and shining.Frontal lobes weakly striate.Mesosoma irregularly rugose, rugae on pronotal disc inverted U-shaped rugae, metapleuron rugose, sides and declivity of propodeum transversely rugose.Petiolar node smooth and shiny except basal area faintly striate.Gaster smooth and shining, except distinctly punctate first gastral tergite.Dorsum of body with abundant suberect to subdecumbent hairs and decumbent pubescence, hairs on cephalic dorsum sparse; scapes and tibiae with dense decumbent pubescence.Body reddish brown to brown; antennae, legs and petiole yellowish brown.
Recognition.The species is similar to A. lanyuensis Leong et al., 2018, A. validus Bharti et Wachkoo, 2013and A. victoriae Shattuck et Slipinska, 2012, but well separated from them by the following characters: dorsal outline of pronotum gradually sloping anteriorly, not forming a straight outline with mesonotum and propodeum; pronotal disc with dense inverted U-shaped rugae; scapes just reaching to posterior corner of head.
Distribution.Known from southern India east through SE Asia to Australia and onwards to the Cook Islands (Shattuck and Slipinska 2012).In China, the species is distributed in Fujian, Guangxi, Hainan and Yunnan.Leong et al., 2018).
In full-face view head longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin without denticles; apical portion with three distinct teeth.Antennae 12-segmented; scapes not exceeding to posterior corners of head.Eyes moderate-size.
In lateral view mesosoma stout, dorsal outline of posterior half of pronotum and mesonotum straight.Posterolateral corners of propodeum obtusely angulate.Petiole thin, distinctly higher than long, with acute triangular tip; anterior margin straight, posterior margin distinct convex; subpetiolar process developed with subtriangular ventral margin.Dorsal margin of petiole weakly concave in anterior view.
Frons and anterior part of vertex longitudinally striate extending to posterior lobes of head, remainder of head smooth and shining.Clypeus smooth and shining.Pronotum longitudinally striate.Mesonotum and propodeum transversely striate.mesopleuron smooth and shining.Petiolar node smooth and shiny except basal area faintly striate.Gaster smooth and shining.Dorsum of body with abundant erect to suberect hairs and abundant decumbent pubescence; scapes and tibiae with scattered subdecumbent hairs dense pubescence.Body reddish brown; antennae, legs and petiole yellowish brown.
Recognition.The species is similar to A. ruginotus Stitz, 1925, but can be distinguished from the latter by the following characters: eyes larger with 12 ommatidia along the maximum diameter; dorsal outline of mesosoma straight.
Distribution.Known only from the type locality -Orchid Island of Taiwan.
[holotype worker and 1 paratype worker are deposited in the Insect Collection, Guangxi Normal University, Guilin, China (GXNU); 1 paratype worker will be deposited in the Insect Collection, Southwest Forestry University, Kunming, Yunnan Province, China (SWFU); 1 paratype worker will be deposited in the Institute of Zoology, Chinese Academy of Sciences, Beijing, China (IZCAS)].In full-face view head longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin without denticles, apical portion with three distinct teeth.Anterior margin of clypeus gently concave.Antennae 12-segmented; scapes long, surpassing to posterior corners of head by about 1/7 of its length.Maximum diameter of eye wider than apical width of mandible.
Frons with striae running in a fan shape, remainder of head smooth and shining.Mesosoma smooth and shining, pronotum with transverse striae on pronotal neck, dorsa of mesonotum and propodeum transversely striate.Petiolar node smooth and shiny except lower half area faintly striate.Gaster smooth and shining.
Dorsum of body with scattered erect hairs; mandibles with abundant subdecumbent pubescence; scapes and tibiae with sparse suberect hairs and dense decumbent pubescence.Body yellowish brown; legs brownish yellow.
Recognition.The new species is similar to A. rufus (Jerdon, 1851), but well separated from the latter by the following characters: sides of pronotum smooth and shining; metanotal groove widely depressed; junction of propodeal dorsum and declivity forming a pair of small lateral teeth; the constriction between AIII and AIV with short ridges.
The new species is also similar A. agilis Emery, 1901, but well separated from the latter by the following characters: mesonotum smooth and shining; junction of propodeal dorsum and declivity forming a pair of small lateral teeth; petiolar node narrowly pointed at apex; the constriction between AIII and AIV with short ridges; body yellowish brown.

Anochetus madaraszi Mayr, 1897
In full-face view head slightly longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin without denticles; apical portion with three distinct teeth.Antennae 12-segmented; scapes just reaching to posterior corners of head.Eyes large, maximum diameter wider than basal width of scape.
Central dorsum of head and frontal lobes longitudinally striate, remainder of head smooth and shining.Pronotum and propodeal dorsum irregularly rugose.Mesonotum and propodeal declivity transversely striate.Propodeal sides obliquely striate.Mesopleuron smooth and shining.Petiole smooth and shining, basal area obliquely striate.Gaster smooth and shining.
Body dorsum with scattered suberect hairs and sparse decumbent pubescence; scapes and tibiae with dense decumbent pubescence.Body blackish brown to brown; antennae, legs yellowish brown.
Recognition. A. madaraszi is similar to A. graeffei Mayr, 1870, but can be separated from the latter by the following characters: head slight longer than broad (CI 90-92); mesonotum with transversely striate; petiolar node distinctly thick; first gastral tergite smooth and shining.
Distribution.Known from Bangladesh, India, Sri Lanka, China: Guangxi and Yunnan (new record).
Holotype worker.TL7.In full-face view head longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin with 11 denticles; apical five denticles equally sized, remaining denticles gradually decreasing in size towards base; apical portion with three distinct teeth.Clypeus with concave anterior margin, lateral portion forming two round lobes above the base of mandibles.Antennae 12-segmented; scapes long, surpassing to posterior corners of head by 1/10 of its length.Eyes moderately large; maximum diameter of eye equal to the basal width of mandibles.
In lateral view mesosoma slender; pronotum moderately convex.Promesonotal suture narrowly notched.Mesonotum with a transverse ridge anteriorly.Metanotal groove deeply depressed.Dorsum of propodeum almost straight, sloping posteriorly; posterodorsal coner of propodeum narrowly rounded.Petiole cone-shaped, with a pointed dorsal apex, anterior margin slightly longer than posterior margin; subpetiolar process developed, directed posteroventrally as a distinct hook.
Frons longitudinally to obliquely striate posteriorly; remainder of head smooth and shining.Mesosoma smooth and shining, upper portion of lateral pronotum longitudinally striate, metathorax and propodeum obliquely rugose.Petiolar node smooth and shining, basal area faintly striate.Gaster smooth and shining.
Body dorsum with abundant erect to suberect hairs and sparse decumbent pubescence; scapes with sparse suberect hairs and abundant subdecumbent pubescence, tibiae with abundant suberect hairs and sparse decumbent pubescence.Body reddish brown; head, mandibles and antennae blackish brown; legs yellowish brown.
Recognition.The new species is similar to A. princeps Emery, 1884, but can be distinguished from the later by the following characters: scapes surpassing to posterior corners of head by 1/10 of its length; petiole cone-shaped, with a pointed dorsal apex.
Distribution.Known only from the type-locality Medog of China.
In full-face view head longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin with 9-10 denticles; apical portion with two distinct large teeth, sometimes with 1 small additional denticle on the midlength of the ventral tooth.Antennae 12-segmented, scapes just surpassing to posterior corners of head.Eyes moderately large, maximum diameter equal to the basal width of mandibles.
Recognition. A. mixtus is similar to A. rugosus (Smith, 1857), but can be distinguished from the latter by the following characters: vertex smooth and shining; upper half of petiolar node smooth and shining, basal half weakly striate.
Distribution.Known from Vietnam and China: Yunnan, Guangxi and Hainan.Workers. .

Anochetus risii
In full-face view head longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin with several denticles, gradually decreasing in size towards base; apical portion with three distinct teeth.Antennae 12-segmented; scapes surpassing to posterior corners of head by about 1/5 of its length.Eyes large, maximum diameter of eye wider than the basal width of mandibles.
Frons longitudinally to obliquely striate posteriorly; frontal lobes and clypeus weakly striate, remainder of head smooth and shining.Mesosoma smooth and shining, propodeum and lower part of metapleuron obliquely rugose.Sometimes sides of pronotum weakly longitudinal rugose.Petiole smooth and shining, basal area weakly striate.Gaster smooth and shining.Body dorsum with abundant erect to suberect hairs and dense decumbent pubescence; scapes and tibiae with scattered suberect hairs and dense decumbent pubescence.Body blackish brown; antennae and legs yellowish brown.
Recognition and discussion.After detailed comparison of type worker images of A. risii (CASENT0907411) and A. taiwaniensis (CASENT0902440 & CASENT0915167), we noticed that both species have completely consistent characters in head, mandibles, antennae, eyes, mesosoma, petiole and measurement range.Terayama (1989) pointed out that A. taiwanensis is distinguished from A. risii by "broader mandibular shafts and small denticles of the dorsal inner margin of the mandible in the former".However, we are unable to recognize these differences.The only difference between them is that A. taiwaniensis has the pronotum weakly rugose laterally.Consequently, we consider it safe to propose A. taiwaniensis as a junior synonym of A. rissi here.
Distribution.Known from Vietnam, Indonesia and Southern China.Workers.TL 4. .

Anochetus subcoecus
In full-face view head longer than broad, posterior margin strongly concave.Mandibles linear, gradually broadened apically; inner margin without denticles; apical portion with three distinct teeth.Antennae 12-segmented; scapes short, not reaching to posterior corner of head.Eyes very small.
In lateral view mesosoma stout.Pronotum moderately convex.Promesonotal suture narrowly impressed.Dorsal margin of mesonotum nearly straight, weakly sloping posteriorly.Metanotal groove weakly concave.Dorsum of propodeum almost straight, posterodorsal corner with a pair of short blunt teeth.Petiole thin and erect, long triangle shaped, narrowing apically, anterior margin straight, posterior margin weakly convex, dorsal margin acute; subpetiolar process developed, nearly rectangular and angled ventrally.
Recognition.This species can be easily separated from other named species of this genus by its very small eyes and distinct propodeal teeth.

Revival of the valid status of Anochetus gracilis
Anochetus gracilis Karavaiev, 1925, stat. n. Fig. 11 Anochetus gracilis Karavaiev, 1925: 286.Junior synonym of Anochetus risii : Brown, 1978: 558.Material examined.Two syntype worker images examined, AntWeb, CASENT0916847 & CASENT0915166, photos by Will Ericson.Recognition and discussion.After observation of the syntype worker images of A. risii (Fig. 8) and A. gracilis (Fig. 11) from AntWeb, we find that there are clear differences between them: 1) inner margin of mandibles has no denticles in the worker of A. gracilis, but possesses several distinct denticles in the worker of A. risii; 2) the maximum diameter of eye is much larger than the maximum width of mandible in the worker of A. gracilis, but smaller than or just equal to maximum width of mandible in the worker of A. risii; 3) pronotal sides distinctly striate in the worker of A. gracilis, but smooth and shining in the worker of A. risii.Therefore, the status of A. gracilis is restored from the synonymy of A. risii here.

Figure 1 .
Figure 1.Anochetus graeffei worker (No.G160161).A head in full-face view B mandible in anterior view C body in dorsal view D body in lateral view.

Figure 2 .
Figure 2. Anochetus lanyuensis holotype worker (Cited from Leong et al., 2018).A head in full-face view B mandible in anterior view C mesosoma in dorsal view D mesosoma in lateral view.

Figure 3 .
Figure 3. Anochetus longus holotype worker (No.G150887).A head in full-face view B mandible in anterodorsal view C body in dorsal view D body in lateral view.

Figure 4 .
Figure 4. Anochetus madaraszi worker (No.G160654).A head in full-face view B mandible in anterior view C body in dorsal view D body in lateral view.

Figure 5 .
Figure 5. Anochetus medogensis holotype worker (No.G160654).A head in full-face view B mandible in anterior view C body in dorsal view D body in lateral view.

Figure 6 .
Figure 6.Anochetus mixtus worker (No.G140095).A head in full-face view B mandible in anterior view C body in dorsal view D body in lateral view.

Figure 7 .
Figure 7. Anochetus risii worker (No.G140447).A head in full-face view B mandible in anterior view C body in dorsal view D body in lateral view.

Figure 8 .
Figure 8. Anochetus risii worker (Syntype, AntWeb, CASENT0907411, photos by Will Ericson).A head in full-face view B labels C body in dorsal view D body in lateral view.

Figure 9 .
Figure 9. Anochetus taiwaniensis, syn.n. (Paratype, AntWeb, CASENT0915167, photos by Will Ericson).A head in full-face view B labels C body in dorsal view D body in lateral view.

Figure 10 .
Figure 10.Anochetus subcoecus worker (No.G160632).A head in full-face view B mandible in anterior view C body in dorsal view D body in lateral view.

Figure 11 .
Figure 11.Anochetus gracilis worker (Syntype, AntWeb, CASENT0916847, photos by Will Kate Martynova).A head in full-face view B labels C body in dorsal view D body in lateral view.