A New Species of the Ant Genus Strongylognathus (Hymenoptera, Formicidae) from Inner Mongolia, with Notes on the Species Reported from China
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ASIAN MYRMECOLOGY Volume 9, e009016, 2017 ISSN 1985-1944 | eISSN: 2462-2362 © Alexander G. Radchenko, DOI: 10.20362/am.009016 Yichen Zhang and Jürgen Heinze A new species of the ant genus Strongylognathus (Hymenoptera, Formicidae) from Inner Mongolia, with notes on the species reported from China Alexander G. Radchenko1*, Yichen Zhang2 and Jürgen Heinze3 1Schmalhausen Institute of Zoology of the National Academy of Sciences of Ukraine, B. Khmelnitskogo str., 15, Kiev-30, 01030, Ukraine 2High School Affiliated to Beijing Normal University, No.18 Nan Xin Hua Street, 100052, Beijing, China 3Zoology / Evolutionary Biology, University of Regensburg, 93040 Regensburg, Germany *Corresponding author: [email protected], [email protected] ABSTRACT. A new species, Strongylognathus dao sp. n. is described based on all three castes from Inner Mongolia, China. It belongs to the S. huberi spe- cies-group and differs from the related species S. koreanus Pisarski by the pres- ence of standing hairs on the temples and genae, by the distinctly darker color of the body, and also by the relatively shorter, higher and wider postpetiole. Its workers differ from S. christophi Emery by the longer head and by the much less developed longitudinal rugosity on the sides of mesosoma. Besides this, queens (gynes) of S. dao are much smaller than those of S. christophi. In this study, we describe what appears to have been an incomplete raid of S. dao on a neighboring Tetramorium tsushimae Emery colony. A brief review of Chinese Strongylognathus species is provided. We believe that previous records of S. karawajewi Pisarski and S. cheliferus Radchenko from China were based on misidentifications and propose to remove these two species from the list of Chinese ants. Keywords: Strongylognathus dao, Tetramorium, dulotic ants, Key, taxonomy INTRODUCTION izes colonies of various species of Tetramorium Mayr, 1855, and is distributed in North-West Af- More than 15000 described ant species are known rica, Central, Southern and Eastern Europe, Ana- presently, but only a few hundred of them are so- tolia, Middle East, Caucasus, Iran, Afghanistan, cial parasites, which temporarily or permanent- Pakistan, Central Asia, Kazakhstan, West Sibe- ly depend on workers of other species to found ria, Eastern China, Korea, and Japan. Despite a and maintain their colonies (Buschinger 2009). remarkable number of reports on its presence in With approximately 25 described, and at least Tetramorium nests (e.g., Pisarski 1965; Acosta & three additional, not yet formally described spe- Martínez 1982; Radchenko 1991; Sanetra et al. cies (Paknia et al. 2010; our unpublished data), 1999; Radchenko & Dubovikoff 2011; Vesnić Strongylognathus Mayr, 1853 is the most species- 2013), little is known about its life history. This is rich and most widely distributed genus of social explained by the patchiness of its occurrence and parasites in the subfamily Myrmicinae. It parasit- the huge size of the host nests. 2 Alexander G. Radchenko, Yichen Zhang & Jürgen Heinze Strongylognathus differs from all other strongly concave occipital margin and prominent Palearctic myrmicine ants by their peculiar fal- posterio-lateral corners of the head. In contrast, cate, i.e. saber-shaped, toothless mandibles with- the species of the huberi-group have a straight or out a defined masticatory margin. Young Stron- at most very shallowly concave occipital margin gylognathus queens usurp Tetramorium colonies, and rounded, not prominent posterio-lateral cor- where they either replace or live alongside the ners of the head. resident queen, apparently suppressing the pro- Here we describe a new species from the duction of host sexuals. Strongylognathus work- huberi species group, S. dao, from Xilin Gol, In- ers rarely or never engage in hunting prey or ner Mongolia, China, and present a key for iden- handling the brood. Instead, workers of several tification of the species that are presently known species of the S. huberi group are thought to en- to occur in China. gage in active slave raids, i.e., they attack neigh- boring host colonies and retrieve their brood to replenish the stock of host workers in their own MATERIALS AND METHODS colony (Forel 1900; Kutter 1920, 1923; Sanetra & Güsten 2011). Active raiding has been ob- The new species is described based on ca. 50 served in staged confrontations in experimental workers, 3 gynes and 17 males, collected at the arenas in S. alpinus Wheeler, 1909 and S. afer Research Station of Animal Ecology on Grass- Emery, 1884 (Kutter 1920, 1923; Sanetra & land, Maodeng, Xilinhaote, Inner Mongolia, Chi- Güsten 2001), and Forel (1904) reported on a na. The holotype specimen is stored in the col- column of S. rehbinderi Forel, 1904 carrying pu- lection of the Schmalhausen Institute of Zoology pae in the field. In contrast,S. testaceus Schenck, of the National Academy of Sciences of Ukraine, 1852 and S. karawajewi Pisarski, 1966 appear to Kiev (SIZK). The paratypes are stored in SIZK, be queen-tolerant inquilines and do not engage in the National Zoological Museum of China, Insti- slave raids (Wheeler 1907; Sanetra et al. 1999; tute of Zoology, Chinese Academy of Sciences, Sanetra & Buschinger 2000). Beijing, and in the University of Regensburg, Based on the placement of S. testaceus Germany. within Tetramorium in the phylogeny of the Myr- Original photos were taken using an micinae, Ward et al. (2015) considered Strongy- Olympus SZX10 stereomicroscope, connected to lognathus as a senior synonym of Tetramorium, an Olympus C-4040ZOOM digital camera, using though refrained from formal synonymization LAS 3.0 and then stacked using the Helicon Fo- of these names (see also Sanetra & Buschinger cus Pro software package. 2000). Nevertheless, we chose a name for the Measurements of specimens (accurate new species that would not need to be changed if to 0.01 mm) were taken for each caste and these general agreement about the naming of Tetramo- were used to calculate various indices: rium and Strongylognathus were reached. In general, the taxonomy of Strongylo- HL – maximum length of head in dorsal view, gnathus is comparatively well studied. The most measured in a straight line from the most recent regional taxonomical reviews and/or de- anterior point of clypeus to the posterio- scriptions of new species have been carried out most point of occipital margin; by Pisarski (1966), Baroni Urbani (1969), Bolton (1976), Radchenko (1985, 1991, 1995), Sanetra HW – maximum width of head in dorsal view et al. (1999), Sanetra & Güsten (2001), Wei et behind (above) the eyes; al. (2001), Radchenko & Dubovikoff (2011) and Borowiec & Salata (2013), but a comprehensive FW – minimum width of frons between the revision of the whole genus has not yet been frontal carinae; undertaken. Bolton (1976) divided the genus in two species-groups: the testaceus- and huberi- FLW – maximum distance between the outer groups. The species of the first group have a borders of the frontal lobes; New species of Strongylognathus from China 3 SL – maximum straight-line length of scape PH – maximum height of the petiole in profile, from its articulation with condylar bulb to measured from the uppermost point of the the proximal edge of scape; petiolar node perpendicularly to the low- ermost point of the ventral face of petiole OL – maximum diameter of the eye; (excluding subpetiolar lobe); GnL – length of the gena, measured from the PPL – maximum length of the postpetiole from anterior edge of eye to the anterior edge of above; the gena (malar distance); PPW – maximum width of the postpetiole from TpL – length of the temple, measured from the above; posterior edge of eye to the posteriormost point of temple; PPH – maximum height of the postpetiole in profile from its uppermost to lowermost ML – diagonal length of the mesosoma seen in points, measured perpendicularly to the profile, from anterior end of the neck shield linear component of the lateral postpeti- to the posterior margin of propodeal lobes olar suture. (workers) and from the most anterodorsal point of mesosoma to posterior margin of For simplicity, we give ratios of various propodeal lobes (queens and males); measurements (e.g. HL/HW instead CI) rather than name and abbreviate various indices (e.g. MH – height of the mesosoma, measured from CI) as we have done elsewhere. the upper level of mesonotum perpendicu- larly to the level of lower margin of meso- pleuron; DESCRIPTION OF THE NEW SPECIES PNW – maximum width of the pronotum in dor- Strongylognathus dao Radchenko, Zhang et sal view (workers); Heinze, sp. nov. (Figs. 1-3) SCW – maximum width of the scutum in dorsal view (queens and males); Material examined. Holotype: worker, China, Inner Mongolia, Research Station of Animal SCL – length of the scutum+scutellum in dorsal Ecology on Grassland of Chinese Academy of view (queens and males); Sciences on 307 Provincial Road, Maodeng, Xilinhaote, N 44° 11’ 04”, E 116° 27’ 38”, 1085 HTL – maximum length of hind tibia, measured m a.s.l., July 30, 2016, in nest of Tetramorium from the junction with femur to the junc- tsushimae under a tile provided as experimen- tion with the first tarsal joint. tal shelter for small rodents, leg. J. Heinze and Yinchen Zhang (SIZK). Paratypes: ca. 40 work- PL – maximum length of petiole from above, ers, 3 gynes and 17 males from the nest of holo- measured from the posterodorsal margin type; 8 workers, collected on July 31, 2016 from of petiole to its anterior edge at the articu- a second nest in soil during a raid approximately lation with propodeum; petiole should be 300 m away from the other nest (SIZK, National positioned so that measured points lay on Zoological Museum of China, University of Re- the same plane; gensburg, Germany). Unique specimen identi- fiers are: holotype worker – CASENT0916954, PW – maximum width of the petiole from paratype gyne – CASENT0916955, paratype above; male – CASENT0916956 (all these are preserved in SIZK).