Flacopimpla barathrica Fritzén, 2014

Fritzén, Niclas R., 2014, Two new species of the Polysphincta genus-group (Hymenoptera: Ichneumonidae: Pimplinae) reared from their spider (Araneae) hosts in Europe, Zootaxa 3894 (1), pp. 117-130 : 119-124

Flacopimpla barathrica Fritzén , sp. n.

Figs 1–10 .

MATERIAL EXAMINED. FINLAND: Holotype ♀ ( ZMUT) , Sb , Kuopio , Kangasmäki, Pirunpesä, 62° 50.27'N; 27° 59.87'E, inside a small cave in a small ravine, ex adult ♀ Thymoites bellissimus coll. 18.vi.2011, coc. 25.vi.2011, em. 3.vii.2011 (N.R. Fritzén) . Paratypes: 1♂ ( NRF) 2♀ ( BMNH, NRF) , Ks , Kuusamo , Kiutaköngäs (Oulanka National Park), in clefts and crevices on rock wall in gully of Oulankajoki river, 66° 22.05'N; 29° 19.68'E, coll. as cocoon 15.vi.2011, em. 18– 24.vi.2011 (N.R. Fritzén); 2♀ ( NRF) , Ks , Kuusamo , Kiutaköngäs (Oulanka National Park), 66° 22.09'N; 29° 19.75'E, on boulder and on rock wall with crevices in or near gully of Oulankajoki river, coll. as cocoon 19.vi.2011, em. 24–26.vi.2011 (I. Österblad); 2♂ ( NRF) , Tb , Jyväskylä , Veijo , 61° 56.95'N; 25° 41.75'E, in hollows between boulders beneath rock wall, ex subadult Thymoites bellissimus coll. 10.v.2012, coc. 17–18.v.2012, em. 25–26.v.2012 (N.R. Fritzén); 3♀ 1♂ (1♀ NMS, 2♀ 1 ♂ NRF), Oa , Korsholm , Södra Vallgrund , Sommarö , 63° 09.81'N; 21° 18.32'E, in old concrete garden cellar, ex subadult and adult Thymoites bellissimus coll. 25–27.ix.2012, coc. 14–17.x.2012, em. 25–27.x.2012 (N.R. Fritzén); 4♀ 3♂ (1♀ ZISP, 1♂ ZMUT, 3♀ 2♂ NRF), Oa , Vasa, Östmelmo, 63° 04.77'N; 21° 41.72'E, beneath boulders in mixed forest dominated by pine, ex adult and subadult Thymoites bellissimus coll. 17.ix.2013, coc. 3–15.x.2013, em. 9–24.x.2013 (N.R. Fritzén); 1♂ ( NRF) , the same data except dates, coll. 29.xii.2013, coc. 11.i.2014, em. 22.i.2014 (N.R. Fritzén); NORWAY: 1♀ ( NRF) , Nord-Fron , Steinåa , 61° 32.01'N; 09° 58.89'E, steep stream canyon, under overhanging moss, ex Thymoites bellissimus coll. 10.v.2013, coc. 20.v.2013, em. 30.v.2013 (A. Fjellberg); SWEDEN: 1♂ 2♀ (1♀ NRM, 1♂ 1♀ NRF), Vb , Vindeln , Krycklan, 64° 13.02'N; 19° 50.15'E (~350 meters upstream from Krycklan Nature Reserve), beaten from beneath overhanging moss at edge of the stream, ex 2 ad. ♀ and 1 subad. ♂ Thymoites bellissimus coll. 7.ix.2013, coc. 12–16.x.2013, em. 21–25.x.2013 (N.R. Fritzén) . Other material: SWEDEN: 1♀ ( NRM) , Vb , Vindelns kommun, Svartbergets försökspark, Åheden, Svartberget, 64° 13.831'N; 19° 47.106'E, (=TrapID 61), 23.vii–05.viii.2004 (=coll. event ID 1302) (Malaise trap in glade in pine forest) ( SMTP) .

Diagnosis. The new species may be separated from the five known North and Central American species of Flacopimpla by the combination of the following characters: 1) smooth, polished and more or less glabrous mesoscutum, 2) complete submetapleural carina, 3) more or less uniformly dark brown mesosoma , 3) the ovipositor with only a very weak swelling at the extreme base and with its thin apical part relatively long and 4) mid trochanter unmodified.

Description. Holotype ♀, length of body 5.0 mm, of fore wing 4.2 mm.

Head. Malar space 1.1x basal mandibular width, without subocular sulcus but with band of coriaceous sculpture. Mandible with upper tooth slender, upcurved and distinctly longer than lower tooth ( Fig. 2 ). Face 0.9x as wide as medially high, polished, with coarse sparse setae. Apex of clypeus relatively long and narrow, about 0.35x width of face. Eyes from anterior view of head conspicuously protruding. Antenna with 21 flagellomeres, lengthto-width ratio of first flagellomere 7.2, of second 4.0. Palpal formula 5:4. Head, in dorsal view, with gena strongly receding and weakly rounded; posterior ocellus separated from eye by 1.2x its own maximum diameter; occipital carina mediodorsally complete.

Mesosoma . Pronotum laterally glabrous, smooth and polished with very weak reticulation; anteriodorsal margin reflexed and produced into a backwardly directed mediodorsal blunt tooth with backwardly directed incomplete longitudinal crest not reaching hind margin of pronotum; hind margin of pronotum mediodorsally with distinct forwardly directed protrusion; epomia more or less straight, reaching dorsal margin of but not continuing across pronotal collar. Mesoscutum smooth and highly polished, almost bare with sparse setae laterally on lateral lobes and anteriolaterally on median lobe; notauli relatively weakly impressed. Mesopleuron smooth and highly polished, dorsally, ventrally and anteriorly pubescent; epicnemial carina extending dorsally beyond ventral corner of pronotum. Mesosternum pubescent. Metapleuron convex, polished and moderately smooth, central area hirsute, dorsal and ventral border glabrous; submetapleural carina strong and complete. Propodeum subpolished, area spiracularis and area lateralis hirsute and weakly rugulose, elsewhere coriaceous; area petiolaris not D-shaped nor any other area completely enclosed by strong carinae, transverse carinae only as vestiges, lateromedian longitudinal carinae indicated by faint ridges only, with shallow longitudinal trough between them, lateral longitudinal carinae short, reaching forwards 0.3 to spiracle, area petiolaris with similarly short but strong median crest; pleural carina complete but weak. Fore wing with 2 rs -m short, about as long as broad, base of 1 m -cu separated from Cu 1 a by distance equal to length of Cu 1 b, cu-a postfurcal and separated from Rs & M by distance 0.5x its length. Hind wing with distal abscissa of Cu 1 present but relatively weak, joining cu-a closer to 1 A than to M, at distance of 0.37 from 1 A towards M. Mid trochanter unmodified. Length of hind femur 5.6x breadth. Hind tibia with inner surface with more or less glabrous longitudinal relatively weak furrow ( Figs 3–5 ).

Metasoma. Tergite 1 of metasoma 1.3x as long as posteriorly broad, coriaceous, with lateromedian carinae extending 0.45 of length of segment, continuing posteriad as dull ridges to 0.8 of length of segment; tergite 2 0.9x as long as posteriorly broad; tergite 3 0.7x as long as posteriorly broad; tergites 2–3 each with moderately defined raised rhombic coriaceous/trans-strigose central area. Ovipositor 0.5x as long as hind tibia, projecting beyond apex of metasoma by 0.22x length of hind tibia, almost straight, with only weak swelling and no distinct bending at extreme base, with moderately strong swelling before middle with maximum at 0.39x length at upper valve and 0.31x at lower valve, after which tapering into long fine tip.

Colour. Head dark brown; clypeus and orbits concolorous with rest of head; mandibles fulvous; palpi whitish, antenna brownish with scape and first flagellomere ventrally pallid. Mesosoma more or less uniformly dark brown except for fulvous to fuscous mesepimeron, subalar prominence, scutellum and thin longitudinal stripe on collar of pronotum; tegula whitish. Metasoma more or less uniformly brown. Front and middle legs fulvous, with coxae, trochanters and trochantelli whitish; hind leg fuscous with trochanter and trochantellum fulvous, and coxa and distal third and dorsal fleck at 0.25 from base of tibia darker brown. Wings hyaline; pterostigma brown.

Paratypes. Resemble holotype in colouration and structure. Fore wing with 2 rs -m slightly longer than in holotype in some specimens. Hind wing with distal abscissa of Cu 1 present in all specimens, but in some specimens faint and near base of 1 A. Females: Body length 3.6–4.9 mm. Fore wing length 3.1–4.2 mm. Antennal flagellomeres 21–23. Ovipositor from slightly bent upwards to slightly decurved (probably as a result of airdrying). Males: Body length 3.0– 4.5 mm. Fore wing length 2.8–3.8 mm. Antennal flagellomeres 21–22. Metasoma on average narrower than in females. Lack glabrous longitudinal furrow on inner surface of hind tibia.

Other material. The colouration and structure of the single specimen fall within the variation of the holotype and paratype females, except for the presence of two distinct pronotal swellings on both sides running from the base of the fore wing downwards to the pronotal collar and anteriad along the lower margin of the mesoscutum, respectively.

Type locality. A small ravine called Pirunpesä (En. Devils nest) in the eastern part of the Kangasmäki Hill in the village of Suojärvi in Kuopio , in the fauna province of Savonia borealis in the central part of Finland, N 62° 50.27' E 27° 59.87', altitude ca. 150 m. The Pirunpesä-ravine is about 100 m long with 4–8 m high rock walls with small fissure caves ( Fig. 6 ). The Kangasmäki Hill is classified as locally significant cliffs/rocky hills for the North Savo region (Husa et al. 2001) .

Distribution. Boreal forest zone of Fennoscandia.

Etymology. The specific name refers to the troglophilic habits of the species but is particularly associated with the name of the type locality (Barathrum = chasm, abyss, hell; in ancient Greece a pit at Athens into which criminals were cast).

Natural history. Flacopimpla barathrica sp. n. is a koinobiont ectoparasitoid of Thymoites bellissimus (Theridiidae) . All specimens of the type series (n = 24) were found as larva on T. bellissimus or as cocoon in or close to webs with this spider species. They were all found in caves, clefts and other cavities on rock walls, in hollows between boulders or in a similar habitat of antropochorous origin, or in other partly subterranean places like under overhanging moss on river banks. It overwinters as a minute larva on its host within these concealed sites. The larval placement varies from dorsolateral to almost lateral and from the posterior to the anterior part of the host’s abdomen ( Figs 7–8 ). Based on all the parasitised specimens of T. bellissimus collected (some of which not successfully reared) the head of the larva usually (n = 28) points towards the posterior part of the host abdomen, but rarely (n = 3) the head points anterioventrally, but only when the larva is at the anterior extreme of the host abdomen. The cocoon is subcylindrical, diaphanous with springy and loosely woven whorls of yellowish white colour ( Figs 9–10 ) with a distinct caudal orifice. It is built vertically with its anterior apex usually attached to the upper substrate, in the case of all cocoons collected in the field (n = 14) or empty ones seen, they have been attached to the upper rock surface ( Fig. 9 ). Among the other European species of the Polysphincta genus-group, the cocoon could be confused with those of Z. bohemani (Holmgren, 1860) , Z. percontatoria (Müller, 1776) , Z. discolor (Holmgren, 1860) and Z. anomala (Holmgren, 1860) , at least the first two of which can be found on rock walls. Of the 13 cocoons with pupae, tentatively belonging to F. barathrica sp. n, collected at one site in the Oulanka National Park, eight (~60%) were infested by pseudohyperparasitoids of the ichneumonid genus Gelis Thunberg. Based on the collection data of the cocoons, the single imago and unhatched eggs found on the hosts as late as on September 7 and 17, the flight period begins in late June and continues to at least mid September. One larva presumably belonging to the new species (due to the presence of parasitised T. bellissimus at this site in combination with absence of other possible hosts) was seen building its cocoon on September 25, indicating an even longer flight period. Due to the sensitive life stage the larva was not collected and two days later when rechecked it had disappeared.

Remarks. The new species is classified as a Flacopimpla since most of its diagnostic characters correspond better to the expanded Flacopimpla (see Gauld & Dubois 2006) than to Zatypota : a rather slender mandible with upper tooth upcurved ( Fig. 2 ), palp formula 5:4, hind tibia with a hairless longitudinal groove internally ( Figs 3–5 ), propodeum dorsally without areas closed by carinae, propodeum dorsally and the central area of tergites 2–3 coriaceous-strigose and distal abscissa of Cu 1 of hind wing present.

Flacopimpla barathrica sp. n. is morphologically highly similar to the Nearctic F. parva . In its brownish colouration it is, however, rather different from the more colourful F. parva . F. parva has a distinct swelling at the extreme base of the ovipositor. The basal swelling is inconspicuous in F. barathrica sp. n., whose ovipositor is also longer, especially the thin apical part. In the new species, the propodeal carinae seem to be slightly more developed and the propodeum more strongly sculptured than in F. parva . In addition, there are, on average, fewer flagellomeres in F. barathrica sp. n. than in F. parva , the latter of which has 24–25 in females (n=4) and 24 in males (n=2).

Figures

FIGURE 1. Flacopimpla barathrica sp. n.: Holotype in lateral view (slightly straightened) and head in anterior view.

FIGURE 2–5. Flacopimpla barathrica sp. n.: 2—Mandible of a paratype ♀ showing the slender and upcurved upper tooth, 3–5—SEM-images of the inner side of the hind tibia of a paratype ♀ showing the longitudinal glabrous furrow in different magnifications.

FIGURES 6–10. Flacopimpla barathrica sp. n.: 6—type locality at the Pirunpesä ravine in Kuopio, Finland, 7—an adult ♀ of the host Thymoites bellissimus with the larva of the holotype, 8—a subadult ♂ of the same host species infested with both the larva of a paratype and an Iphidosoma physogastris mite, 9—a cocoon with pupa in situ (Oulanka National Park), attached to the upper rock surface in the web of the host and 10—the newly emerged holotype in vitro, still resting on the cocoon. Scale bars 1 mm.