Research Article |
Corresponding author: Mark R. Shaw ( markshaw1945@gmail.com ) Academic editor: Gavin Broad
© 2019 Mark R. Shaw, Jeroen Voogd.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Shaw MR, Voogd J (2019) Notes on the biology, morphology and generic placement of “Hellwigia” obscura Gravenhorst (Hymenoptera: Ichneumonidae, Ophioninae). Journal of Hymenoptera Research 69: 39-53. https://doi.org/10.3897/jhr.69.33662
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The ophionine ichneumonid known as Hellwigia obscura has been reared for the first time, from larvae of Horisme sp. (Lepidoptera: Geometridae) feeding on Clematis vitalba in The Netherlands. The cocoon and the parasitoid’s means of emergence are figured, as are some features of the adult. On a balance of morphological grounds, including some already discussed in the literature, it is proposed that “Hellwigia” obscura should be excluded from Hellwigia and instead be ascribed to the genus Heinrichiella stat. rev. as Heinrichiella obscura comb. n. Reasons for this change as well as for preferring this generic name to Protohellwigia Brues are given
Hellwigia elegans, Heinrichiella, Protohellwigia, Horisme, cocoon, emergence, systematics
No biological information has been published for any of these taxa, and the main purpose of this paper is to present rearing data, and some limited additional biological information, for the nominal Hellwigia obscura. The most appropriate generic name for the species is also considered. The two species described in the genus Hellwigia are not only highly divergent from all other Ichneumonidae, but also from each other (
Most photographs were taken as single images down one arm of a Wild M5A stereomicroscope with x20 eyepieces using a Canon PowerShot 110. The exceptions (Figs
One of us (JV) collected larvae of Horisme spp (Lepidoptera: Geometridae) by beating climbing growth of Clematis vitalba at a relatively open calcareous site, Eyserbos, with abundant hedgerows and woodland edge at Eys, Limburg, The Netherlands on 7.ix.2017. Altogether 50 Horisme spp larvae were collected, in various stages of growth. Three were easily determined as H. vitalbata (Dennis & Schiffermüller) and all produced moths. The remaining 47 comprised both H. radicaria (de La Harpe) and H. tersata (Dennis and Schiffermüller), but the two species could not be separated in the larval stage and they were reared together. Five of these were parasitized by a gregarious species of Microgastrinae (Braconidae) [the adults escaped but by analogy with rearings from Horisme species conducted in England by MRS they were probably Cotesia nothus (Marshall)] before becoming fully grown. One succumbed to a species of Netelia (Netelia) (Ichneumonidae: Tryphoninae) that may be undescribed (Broad and Shaw in prep.), and three prepupae produced banded cocoons that autumn from which adults of the nominal Hellwigia obscura emerged during the period 1–7.v.2018 and were passed on to MRS for determination and incorporation into the NMS collection. In addition, five adult Horisme radicaria and 33 Horisme tersata were reared, the adults of both species emerging between late April and the first half of May 2018. Despite the numerical superiority of H. tersata over H. radicaria in the host sample from which the specimens were reared, it is unfortunately not yet possible to ascertain which, if not both, of these species serves as host, but it is hoped that this can be pursued in years to come.
The tough cocoon (Fig.
At least part of the reason for their still being treated as congeners may stem from the morphological phylogenetic analysis of genera of Campopleginae, which at that time included Hellwigia, conducted by
Similarities between the species include:
Differences, probably including both autapomorphies and plesiomorphies (unassessed here) judged to be important by
The hypandrium (male subgenital plate) which is greatly expanded and ventrally flat (also bearing strong spines) in H. elegans (Fig.
On these grounds
Many of the features in which the two species differ are illustrated but without comment by
Despite the difficulty of associating either of the nominal Hellwigia species with any other taxon, we assert that the very wide morphological separation between them are strong grounds for us to assign the nominal Hellwigia obscura to a different genus. It differs from the fossil Protohellwigia obsoleta in wing venation (figured by
The way in which the adult Heinrichiella obscura comb. n. leaves its cocoon differs markedly from the emergence habits seen in European species of Ophion (a chewed hole involving the removal of many irregular bits) and Enicospilus (a neatly detached cap). Although not directly observed, the unusual means of eclosion of adult Heinrichiella obscura comb. n. must relate closely to the structure of its mandibles. In a few groups of Ichneumonidae (e.g. Diplazontinae, and the genus Banchus (Banchinae), cf.
A series of female Heinrichiella obscura comb. n. in NMS collected by Malaise trap in France (Dordogne) by RR Askew in September (two in the period 1–21.ix.1999 and one 16–30.ix.2000), in conjunction with the present rearings in May, suggests that, like its Horisme hosts, H. obscura is at least bivoltine, and the late dates also indicate that it probably attacks final instar host larvae, as appears to be typical for European Ophioninae (cf.
Given the suggested basal position within Ophioninae of Heinrichiella obscura comb. n. (see below) it is of some significance that its host is a geometrid, a host group that may be ancestral for Ophioninae given also that it is used by a few species of apparently relatively basal Ophion in Europe (
Although
It would, of course, be extremely interesting to discover the host of Hellwigia elegans (apart from capture data, nothing is known of its biology beyond its ovipositor structure (Fig.
It is relevant to point out that the caption for Fig.
We are grateful to Gavin Broad for help with checking and providing literature and arranging the loan of specimens of Hellwigia elegans from the Natural History Museum, London, and for taking photos for Figs