Hemichroa australis (Serville, 1823)

Prous, Marko, Liston, Andrew, Kramp, Katja, Savina, Henri, Vardal, Hege & Taeger, Andreas, 2019, The West Palaearctic genera of Nematinae (Hymenoptera, Tenthredinidae), ZooKeys 875, pp. 63-127 : 63

Hemichroa australis (Serville, 1823)

Tenthredo alni Linné, 1767: 925. Lectotype ♀, designated by Malaise and Benson (1934: 8), not examined, in LSUK (images: http://linnean-online.org/16581/). Type locality: Sweden. Primary homonym of Tenthredo alni Linné, 1758 ( Nematus septentrionalis ( Linné, 1758)).

Tenthredo luctuosa Hill, 1773: 5-6, pl. 1. Syntype(s) ♀, lost. Type locality: Uxbridge (United Kingdom). Treated as nomen oblitum and synonymised with australis by Blank et al. (2009: 32).

Tenthredo australis Serville, 1823: 16. Syntype(s) ♀, lost. Type locality: Midi (France). Nomen protectum, as stated by Blank et al. (2009: 32).

Tenthredo australis Lepeletier, 1823:71. Syntype(s) ♀, lost. Type locality: Midi (France). Primary homonym of Tenthredo australis Serville, 1823.

Hemichroa monticola Ermolenko, 1960: 208-210. Holotype ♀ (Schmalhausen Institute, Kiev: not examined) and 4 female paratypes (one examined). Type locality: Ukraine, Lvovskoj oblasti, Slavekogo rajona, Tuhovalskom perevale. Syn. nov.

Taxonomy.

Ermolenko (1960) stated that australis differs from monticola in the following characters [character state for monticola in brackets]:

- lower surface of antenna noticeably paler than the upper [uniformly dark]

- medial emargination of clypeus deep, usually exceeding half of its length [reaching half of its length]

- intercostal and lanceolate cells of the fore wing and main half of the hind wing are clearly darkened [wings nearly completely hyaline]

- the 2nd anal cell of the posterior wing is almost equal to the length of the median cells [2nd anal cell of the posterior wing noticeably shorter than median one]

- 9th tergum predominantly dark [9th tergum red]

- cerci yellow [cerci basally yellow, apically fuscous]

- valvula 3 of ovipositor on lower margin noticeably convex in lateral view [only slightly convex]

- teeth of the proximal half of the ovipositor have two or more smaller additional denticles at the base [these teeth with only one small additional tooth]

Only a single paratype of monticola was available for examination, but we also examined four females (HNHM) which have the combination of colour characters described for monticola and were collected at subalpine levels in the Ukrainian Carpathians, as was the type series of monticola . We did not observe any significant difference in the depth of the clypeal emargination between Carpathian specimens and australis from other parts of Europe. The other characters used to distinguish monticola are either extremely weak, such as the slightly darkened tips of the cerci and the degree of curvature of the lower edge of valvula 3, or are variable among studied australis females, such as the length of the hind wing anal cell and the presence or absence of denticles on the more basal serrulae of the lancet ( Figs 108-111 ). The shape of sawteeth and the number of serrulae can even vary between the left and right lancets of the same individual ( Figs 108-109 ), possibly as a result of wear (see Schmidt and Walter 1995). Ermolenko considered H. monticola to be a neo-endemic element of the Carpathian subalpine fauna, associated with Alnus viridis , but several of the characters which he gave as distinguishing it from australis occur apparently independently of each other in the australis females which we have examined from many parts of the West Palaearctic. For example, tergum 9 mainly pale, but whole wing-membrane blackish from base of fore wing up to approximately the level of the pterostigma [Germany, Berlin], or antennae entirely black, and wing membrane nearly entirely hyaline, but 9th tergum black [Sweden, Lapland]. In our opinion, Ermolenko underestimated the range of variability in australis , and monticola falls within this range. Therefore, we treat the taxa as conspecific. Nevertheless, comparison of relevant genetic data should still be undertaken.

Previously published descriptions of the male of Hemichroa australis , and the colour characters which are claimed to distinguish it from that of crocea , are partly contradictory, and may not be reliable. Enslin (1915: 317) wrote [translated from German]: "According to Cameron, the male of H. crocea Geoffr. is just like that of H. alni [ australis ]; Cameron (Monograph Brit. Phyt. Hym. II p. 7) saw some males of crocea reared by Fletcher and could not distinguish them from H. alni . Because nothing further on this subject is reported in the literature and it was not possible for us to obtain males of H. crocea for examination, the separation of the males of these species must remain unresolved until a later date". Benson (1958) stated that the male of australis "Differs from crocea ♂ in that the antenna is at least red below [ crocea : antenna entirely black] and the stigma of the wing is piceous [ crocea : pterostigma brown in the middle] ". Smith (1975), in his key to World Hemichroa species, wrote that he did not know the male of australis , and repeated the characters given by Benson (1958). But in the text under H. crocea , Smith (1975) wrote "It may be separated from other species by the presence of the radial crossvein [2r-rs] in the fore wing and characters of the genitalia (figs 3, 4)". The first character state was surely mentioned in error: all Hemichroa species usually possess vein 2r-rs, except for the taxon treated by Smith (1975) as H. militaris (Cresson, 1880), which is currently placed in Dineura ( Fig. 1 , Prous et al. 2014). See below under crocea for additional discussion of diagnostic characters of males of australis and crocea .

Description.

Body length: female 6.5-8.5 mm, male 6.0-6.5 mm. Wing colour highly variable in both sexes, from nearly entirely hyaline, to entire hind wing and basal fore wing up to about pterostigma conspicuously darkened. Female ( Figs 99 , 101 ): Black. Red are head, except more or less for labrum and antenna; pronotum, tegula, mesoscutum, more or less mesoscutellar appendage; more or less the apex of abdomen. Legs black, except for more or less brownish fore legs. Lancet: Figs 106 - 109 . Male ( Fig. 103 ): Head and body entirely black, except more or less for underside of antennae, tegulae, extreme upper posterior edge of pronotum, and subgenital plate. Legs entirely red, except for black coxa and more or less trochanters and trochantelli. One male (DEI-GISHym20617), presumably atypical, has the thorax red and black patterned, exactly as in females. Penis valve: Figs 104-106 ; note the variability in shape of the distal projections.

Our characterisation of the male of australis is based primarily on three specimens from Germany (BC ZSM HYM 04094), Lapland (DEI-GISHym20618), and Japan (DEI-GISHym84982), with identity confirmed by barcoding. Fore wing basally darkened or mostly subhyaline, the antennae black with reddish undersides (or nearly completely pale in the Japanese specimen), and the stigma uniformly dark. The body is completely black, except for the slightly brown tegulae, harpes, and distal edge of sternum 9; and all tibiae completely pale. One further male from Torne Lappmark in the SDEI, and the long series of males from Ukraine, have the same coloration except for mostly subhyaline fore wing. The latter exhibit little variability, except that the tegulae and upper posterior edges of the pronotum may be completely black, or more or less brown, and the antennae usually extensively reddish, but occasionally nearly completely black. The wing veins of the males from Lapland, including the fore wing pterostigma, are, however, darker than the Ukrainian specimens.

Similar species.

See key, and notes on male (above, and under crocea , below). Compared with crocea ( Fig. 112 ), the most obvious differences in the lancet of australis ( Figs 108-111 ) are the greater number and smaller size of ctenidia on the annular sutures, smaller distance between each basal and median sawtooth and its spurette, and its less hooked median sawteeth.

Life history.

Host plants (in Europe): Betula pendula , pubescens ( Kontuniemi 1960), pubescens var. pumila (see Specimens examined), utilis ( Schedl 2010), Alnus glutinosa , incana , and viridis ( Kontuniemi 1960, Pschorn-Walcher and Altenhofer 2000), and further Alnus species in the East Palaearctic. Larvae solitary, and cryptic ( Fig. 88 ). Boevé (2015) compared the defensive strategy of australis and crocea larvae. Two overlapping generations in the lowlands. Although males of both European Hemichroa species have generally been considered to be rare (e.g., Benson 1958, Smith 1975), males of australis are, at least regionally, evidently rather abundant. In a series of 104 specimens collected by Ermolenko in the montane zone of the Ukrainian Carpathians, 92 are males, and 2 of 5 specimens recently collected in the Torne Träsk Region are males. Malaise (1921b) also noted that although males of australis are usually extremely rare, three of six specimens which he collected in the Torne Träsk area were males. Perhaps males are more frequent in areas with a cooler climate, which would represent an interesting departure from the usual pattern in Tenthredinoidea of a higher female to male ratio in warmer areas ( Benson 1950: 126).

Distribution.

Trans-palaearctic from the British Isles, through north and central Europe ( Taeger et al. 2006) to Yakutia ( Sundukov 2017) and Japan ( Smith 1975; see also Specimens examined).

Occurrence in Sweden.

Published records: Skåne ( Andersson 1962), "this species seems to be widespread throughout Sweden" ( Thomson 1871). Material was examined from Skåne, Småland, Östergötland, Bohuslän, Uppland, Västmanland, Jämtland, Lycksele Lappmark, Torne Lappmark.

Specimens examined.

Czech Republic: 1♀ (ZSM). France: Gironde: 1♂ (DEI-GISHym20617), Saucats, 44.65000N, 0.60000W, 16.08.2012, leg. H. Chevin (SDEI). Germany: 17♀ (SDEI, ZSM, ZMHB). 1♂ (DEI-GISHym31923), Bayern, Dingolfing, Stadtwald, 06.06.1992, leg. Liston (SDEI). 1♂ (DEI-GISHym15392), Sachsen, Erzgebirge, Altenberg Umg., 22.07.1985, leg. S. Walter (SDEI). Japan: Honshu: 1♂ (DEI-GISHym84982), Omeshidake W, Road 112, 1900 m, 36.62400N, 138.45400W, 22.07.2016, leg. A. Taeger (SDEI). Russia: Respublika Bashkortostan (Baskiria): 1♀ (DEI-GISHym31837), Burzyanskaya obl. / Baskir Reserve, 53.16666N, 57.50000E, 30.06.1985, leg. V. M. Ermolenko (HNHM). Primorskiy Kray: 1♀, Anisimovka: Gribanovka 1km N, 450 m, 43.12600N, 132.79700E, 18.06.2017, leg. A. Taeger (SDEI). Sweden: Skåne: 1♀ (NHRS-HEVA000006494), no exact locality, leg. Boheman (NHRS). 1♀, Krankesjön, 55.70000N, 13.46666E, 03.08.1974, leg. H. Andersson (MZLU). Småland: 2♀ (NHRS-HEVA000006495-6), no further data (NHRS). 1♀ (NHRS-HEVA000006500), no further data (NHRS). Östergötland: 1♀ (NHRS-HEVA000006498), no exact locality, leg. Wahlgren (NHRS). Bohuslän: 1♀ (NHRS-HEVA000006499), no further data, leg. Boheman (NHRS). Uppland: 1♀ (NHRS-HEVA000003425), Frescati, leg. Malaise (NHRS). 1♀ (NHRS-HEVA000006502), Ulleråkers sjukhus (Asylen) (NHRS). Västmanland: 1♀, Sala kommun, Nötmyran ( Västerfärnebo), birches at Islingby, Östermyran, 59.94198N, 16.30944E, 25.10.2003-08.06.2004, leg. SMTP (NHRS). Jämtland: 1♀ (NHRS-HEVA000006501), no further data (NHRS). Lycksele Lappmark: 2♀ (NHRS-HEVA000006503-4), Sorsele, 29.07.1929 and 05.07.1931, leg. Gaunitz (NHRS). Torne Lappmark: 3♀ (NHRS-HEVA000006505, 6507, 6508), Torne Träsk, 04/06.07.1918 and one without date, leg. Malaise (NHRS). 2♂ (NHRS-HEVA000006510/12), Abisko, 04/08.07.1918, leg. Malaise (NHRS). 1♂ (NHRS-HEVA000006511), Torneträsk, 03.07.1918, leg. Malaise (NHRS). 1♂ (NHRS-HEVA000006513), Kummavuopio, 23.07.1923, leg. Bruce (NHRS). 1♂ (DEI-GISHym20618), Kiruna nr. airport, 450 m, 67.84000N, 20.35000E, 21.06.2012, leg. Liston & Taeger (SDEI). 2♀ (DEI-GISHym15387, 15401), Kiruna nr. airport, 450 m, 67.84000N, 20.35000E, 01.07.2012, leg. Liston & Taeger (SDEI). 1♂, Abisko National Park, E10, 390 m, 68.35300N, 18.81500E, 30.06.2012, leg. Liston & Taeger (SDEI). 1♀, Abisko 9 km E (Stordalen), 400 m, 68.35000N, 19.03500E, 04.07.2016, leg. Liston & Prous (SDEI).1♀, Abisko 6 km W, 650-900 m, 68.34200N, 18.69100E, 02.07.2016, leg. Liston & Prous (SDEI). 1♀, Kiruna, near airport, 450 m, 67.84000N, 20.35000E, 22.06.2016, leg. Liston (SDEI). 1 larva (DEI-GISHym83694), on Betula pubescens var. pumila , Abisko 9 km E (Stordalen) (Sweden: Norrbottens Län), 400 m, 68.35000N, 19.03500E, 05.08.2017, leg. Liston & Prous (SDEI). Switzerland: 3♀ (SDEI, ZSM). Ukraine: 12♀, 92♂ (HNHM), and: 1♀ (DEI-GISHym30203: Paratype of H. monticola Ermolenko), Lvivska Oblast, Slavekogo rajona, Tukhovalsky Pass, 16.08.1957, leg. V. M. Ermolenko (ZISP). 1♀ (DEI-GISHym31836), Ivano-Frankivs’ka Oblast’, Csernogora, Pozsizsevszkaja, 26.06.1975, leg. V. M. Ermolenko (HNHM).

Figures

Figure 1. Maximum likelihood tree of Nematinae based on four genes (COI, NaK, POL 2, TPI). Only specimens sequenced for all four genes were included. Short introns from POL 2 and TPI were excluded. The best-fit model chosen according to Bayesian information criterion was GTR + R 4. Numbers at branches show SH-aLRT support (%) / ultrafast bootstrap support (%) values. Support values for weakly supported branches (<90) are not shown. Letters " f " and " m " stand for " female " and " male ", and are not given for larvae. Numbers at the end of the tip labels refer to the length of the sequence and the number of ambiguous positions (e. g., heterozygosities). The number of ambiguous positions given for two males are due to variation in mitochondrial COI because of possible heteroplasmy. The tree was rooted as in Prous et al. (2014). The scale bar shows the number of estimated substitutions per nucleotide position.

Figures 108 - 112. Hemichroa, lancets 108 - 109 australis DEI-GISHym 15387, Sweden, Torne Lappmark; arrow, spurette 110 australis DEI-GISHym 31836, Ukraine, Carpathians 111 australis DEI-GISHym 31837, Russian Federation, Baskiria 112 crocea DEI-GISHym 19401, Germany, Brandenburg; arrow, spurette.

Figures 98 - 103. Hemichroa 98 - 100 crocea DEI-GISHym 19402 ♀, Germany, Mecklenburg-Vorpommern 99, 101 australis DEI-GISHym 15401 ♀, Sweden, Torne Lappmark 102 crocea DEI-GISHym 31838 ♂, Germany, Mecklenburg-Vorpommern 103 australis DEI-GISHym 20618 ♂, Sweden, Torne Lappmark, fore wing. Scale bar: 2 mm.

Figures 104 - 107. Hemichroa, penis valves 104 australis DEI-GISHym 15392 Germany, Saxony 105 australis DEI-GISHym 20618, Sweden, Kiruna 106 australis DEI-GISHym 84982, Japan, Honshu 107 crocea DEI-GISHym 31838, Germany, Mecklenburg-Vorpommern.

Figures 88 - 97. Larvae of Nematinae 88 Hemichroa australis 89 Nematus lonicerae (photo E. Altenhofer) 90 Nematus wahlbergi 91 Nematus lucidus 92 Euura melanocephalus 93 Nematus latipes 94 Nematus septentrionalis 95 - 96 Nematus alniastri 97 Nematus princeps (photo V. Vikberg).