Zatypota kerstinae Fritzén, 2010

Fritzén, Niclas R., 2010, Natural history and description of Zatypota kerstinae sp. nov. (Hymenoptera: Ichneumonidae) reared from Theridion palmgreni Marusik et Tsellarius (Araneae: Theridiidae) in Finland, Zootaxa 2487, pp. 52-60 : 53-58

Zatypota kerstinae Fritzén , sp. nov.

( Figs. 1–3 )

Holotype female. Body length 4.3 mm. Malar space 0.6X basal mandibular width, subocular sulcus indistinct but with band of coriaceous sculpture. Face 0.8X as wide as medially high, polished, with coarse sparse setae. Antenna with 21 flagellomeres, length-to-width ratio of first flagellomere 5.0, of second 3.2. Head, in dorsal view, with temples wide and evenly rounded behind eye; posterior ocellus separated from eye by 1.2X its own maximum diameter; occipital carina complete but weak. Pronotum bare, smooth and polished; epomia more or less straight and continuing across pronotal collar. Mesoscutum bare, smooth and highly polished, in profile anteriorly distinctly hunched; notauli distinctly impressed. Mesopleuron smooth and highly polished, anterodorsally with some setae and with single row of setae ventro-mesally; epicnemial carina reaching dorsally beyond ventral corner of pronotum. Mesosternum densely pubescent. Metapleuron convex, smooth and polished, dorsal half hirsute. Propodeum polished, pleural area hirsute and weakly rugulose, elsewhere smooth but anteriorly with some setae; lateromedian longitudinal carinae complete but weak, lateral longitudinal carinae weak on periphery of D-shaped area petiolaris but reaching forwards almost to spiracle; pleural carina moderately strong and complete. Forewing length 3.7 mm; 2 rs-m short, slightly longer than broad, base of 1 m-cu separated from Cu 1 a by distance slightly greater than length of Cu 1 b. Hindwing with distal abscissa of Cu 1 entirely absent. Length of hind femur 4.7X its breadth. Tergite 1 of metasoma 1.3X as long as posteriorly broad, polished but weakly striate, with lateromedian carinae extending 0.5 of length of segment; tergite 2 0.75X as long as posteriorly broad; tergites 2–5 each with more or less clearly defined and smooth and polished central area, surrounding furrows polished and rather smooth but with some trans-striae on tergites 2–4. Ovipositor 0.8X as long as hind tibia, projecting beyond apex of metasoma by 0.45X length of hind tibia, straight with distinct swelling at middle of lower valve.

Head black; clypeus fulvous; elongate triangular marks below antennal sockets and facial to frontal orbits yellowish; mouthparts whitish; antenna brownish with scape ventrally pallid. Mesosoma blackish brown; lower corner of propleuron, collar of pronotum from lower corner 3/4 towards epomia, mesepimeron, scutellum and postscutellum fulvous; tegula, subalar prominence, antero-lateral parts of mesoscutum yellowish. Metasoma and ovipositor sheath brown; lateral parts of central area on tergites 2–5 fulvous. Front and middle legs fulvous, with coxae, trochanters and trochantelli whitish, tibia of middle leg with proximal tip brown; hind leg with coxa, trochanters, trochantelli and tarsus fulvous, femur fuscous, proximal and distal 1/3 of tibia dark brown, middle part whitish. Wings hyaline; pterostigma brown.

Paratypes (females). Resemble holotype but have less light markings. Triangular marks below antennal sockets slightly smaller. Mesosoma blackish brown to black; mesoscutum with or without small fuscous flecks on antero-lateral parts of lobes; scutellum dark brown; tegula and subalar prominence as in holotype. Metasoma uniformly coloured, brown or blackish brown. Lateromedian longitudinal carinae of propodeum stronger in some paratype females than in holotype. Ovipositor straight but in most specimens inside or partly inside ovipositor sheath and not clearly seen. Body length 4.3–5.2 mm, forewing length 3.7–4.5 mm. Antennae with 21–22 flagellomeres.

Paratypes (males). Resemble females. Length of hind femur 3.7–4.7X its breadth (stouter in smaller individuals). One male coloured as holotype female, all other males lack lateral fulvous markings of central areas of tergites 2–5 and have yellowish markings on mesoscutum which vary but are smaller than on holotype female. Triangular marks below antennal sockets as in holotype or slightly smaller. Body length 3.0– 4.9 mm, forewing length 2.8–4.2 mm. Antennae with 19–21 flagellomeres.

Material examined. Holotype female: FI Oa: Kristinestad, Högåsen, mature spruce forest, ex subadult Ƥ Theridion palmgreni coll. 21.III.2004, em. 13.IV.2004 (reared indoors, leg. Fritzén, MZH). Paratypes: one female: FI Oa: Korsholm, Jungsund, old spruce forest, ex subadult Ƥ Theridion palmgreni coll. 25.V.2006, em. 14.VI.2006 (reared indoors, leg. I. Österblad, NRF); one female: FI Sb: Savonranta, window trap on dead aspen, 13.VII–10.VIII.1996 (leg. P. Martikainen, RJC); one female: FI Kb: Joensuu, Kolvananuuro, Uuronvaara, old spruce forest, ex subadult Ƥ Theridion palmgreni coll. 12.VI.2008, em. ~ 25.VI.2008 (reared indoors, leg. Fritzén & I. Österblad, NRF); three males: same data as holotype except dates (coll. 21.VIII.2003, em. 17.II.2004; coll. 12.II.2005, em. 7.III.2005; coll. 25.III.2005, em. 18.IV.2005 (all reared indoors, leg. Fritzén, 1 (the first) male NMS, 2 males NRF); one male: FI Oa: Korsholm, Jungsund, small stand of young pines surrounded by mature spruce forest, ex subadult ♂ Theridion palmgreni coll. 12.VIII.2005, em. 5.II.2006 (reared indoors, leg. I. Österblad, NRF); one male: FI Oa: Lapua, Simpsiö, old mixed spruce forest, ex immature Theridion palmgreni coll. 6.V.2005, em. before 25.V.2005 (reared indoors, leg. Fritzén, NRF); two males: FI Ab: Vihti, Siikajärvi 20.VI.1964; 18.VIII–7.IX.1973 (leg. V. J. Karvonen, DAZH); one male: FI Oa: Ilmajoki, Tuomimaa 5.VIII–16.X.2004, window or Malaise trap (leg. V-M. Mukkala, RJC).

Type locality. A spruce-dominated forest about 250 m E of Högåsen in Kristinestad, Finland, N62.266° E21.414°.

Etymology. This beautiful little species is named in honour of my late mother Kerstin Ulla-Britt Fritzén (1940-2001), who was born and lived most of her life in the town of the type locality.

Comments. Before this contribution, six species of Zatypota were known from Europe ( Zwakhals 2006): Z. albicoxa (Walker, 1874) , Z. anomala (Holmgren, 1860) , Z. bohemani (Holmgren, 1860) , Z. discolor (Holmgren, 1860) , Z. percontatoria (Müller, 1776) and Z. picticollis (Thomson, 1888) . The record of a seventh European Zatypota species, Z. pallipes Schmiedeknecht, 1888 ( Yu & Horstmann 1997; Yu et al. 2005), is an error (Fritzén & Várkonyi, in prep.). Zatypota kerstinae is characterised by the almost entirely smooth and polished body and straight ovipositor. Among the European species of Zatypota the combination of straight ovipositor as well as bare, smooth and polished mesoscutum and smooth and polished gastral tergites is found only in Z. picticollis (Thomson) ( Zwakhals 2006) . Zatypota kerstinae is, however, clearly different from Z. picticollis , a proportionately smaller species, which usually has only 15 (range 14–17) flagellomeres, orbits similarly coloured (dark brown) as head (though usually with a yellow fleck or triangle under each antennal socket) and a distinct subocular sulcus. Of the other described Palaearctic species only Z. gracilipes Uchida & Momoi, 1958 , occurring in Japan and the Russian Far East ( Uchida & Momoi 1958; Kasparyan 1976), has the aforementioned combination of features. According to the original description, Z. gracilipes has unusually long and slender mandibles and legs (length of hind femur fully 8.0X its breadth), which is not the case in Z. kerstinae .

I have not examined any Nearctic species. According to Townes & Townes (1960), the combination of straight epomia and smooth and polished mesoscutum and gastral tergites is, among the Nearctic Zatypota species, found in Z. luteipes Townes, 1960 , Z. crassipes Townes, 1960 and Z. alborhombarta (Davis, 1895) . Since Townes & Townes (1960) do not particularly mention it, these three species supposedly also have straight ovipositors, like most species of Zatypota . According to Gauld (1991), Z. alborhombarta has a strong subocular sulcus. Townes & Townes (1960) do not say whether Z. crassipes and Z. luteipes have a strong subocular sulcus or a coriaceous band as in Z. kerstinae . Contrary to those of Z. kerstinae , the frontal orbits (and face) of Z. luteipes are completely black. Both Z. crassipes and Z. alborhombarta have orbital stripes extending beyond the posterior ocelli ( Townes & Townes 1960), while in Z. kerstinae they hardly extend to the hind margin of the anterior ocellus. According to the illustrations of Townes & Townes (1960), the hind legs of Z. crassipes , especially the coxa and femur, are also stouter than in Z. kerstinae .

Females of Z. albicoxa Walker have a curved ovipositor and cannot be mistaken for Z. kerstinae . However, males of Z. albicoxa have an indistinct subocular sulcus with a band of coriaceous sculpture and might be confused with Z. kerstinae . In the collection of DAZH, two males of Z. kerstinae were placed together with one male of Z. albicoxa , all for some reason determined as Sinarachna anomala (Holmgren) [= Zatypota anomala , cf. Zwakhals 2006] with which they have few morphological similarities. Compared to Z. kerstinae , Z. albicoxa is a more slender species with a more elongate body, longer antennae and with more abruptly receding and weakly rounded temples. Zatypota albicoxa is usually much more coloured yellow than Z. kerstinae . However, Z. albicoxa is highly variable in both colour and size, and the proportions of many of its body parts seem to vary with size (i.e. more rounded temples and stouter legs in smaller specimens). Particularly minute dark males, with short antennae and temples almost as convex and rounded as in Z. kerstinae , will certainly cause trouble, especially if there is no host record. Diagnostic features to distinguish Z. albicoxa and Z. kerstinae are listed in Table 1.

Biological notes. The hosts of the reared specimens of the type series of Z. kerstinae are immatures of the theridiid spider Theridion palmgreni . Zatypota kerstinae overwinters as a minute larva positioned dorsolaterally on the host’s abdomen, with which it is aligned ( Fig. 2 a). The placement on the abdomen varies from the anterior to the posterior half. The cocoon of specimens reared indoors under dry conditions is whitish (perhaps more brownish under natural conditions) and densely woven but transparent. Regular loops of looser silk stand out all over its surface, and it also has characteristic erect tufts, especially at the basal half ( Fig. 3 ). The cocoon is unusual for European species of Zatypota of which most have more open, springy cocoons. Among the other European species of the Polysphincta group of genera, the cocoon could be confused with those of Z. albicoxa , Sinarachna nigricornis (Holmgren, 1860) and S. pallipes (Holmgren, 1860) , all of which are slightly more spindle shaped, slightly more densely woven and lack the erect tufts. The cocoon of Z.

kerstinae is built vertically with its anterior apex attached to some threads in the host’s web or to an upper substrate. Based on collection data of four adults, the approximate flight period in Finland is from 20 June to 18 August. Larvae on parasitised spiders collected between 29 July and 21 August (n =7) did not develop past their first instars before diapause.

Figures

FIGURE 1. Zatypota kerstinae sp. nov. Lateral view (holotype female slightly straightened) and head, anterior view.

FIGURE 2. Theridion palmgreni with (a) an overwintering larva (12. II. 2005) of a paratype male of Zatypota kerstinae sp. nov. and (b) the larva of the holotype female of Zatypota kerstinae sp. nov. three days before killing its host.

FIGURE 3. Zatypota kerstinae sp. nov. cocoon. The cocoon is built vertically with its anterior apex attached to some threads in the host's web. It is characterised by erect tufts at its basal end.