Vestalis Selys 1853
Creators: name: Orr, Albert G. W.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Calopterygidae
Vestalis

description: Vestalis
With 16 species occurring from Yunnan, southernmost China, the Philippines and Bali in the east to the western Ghats and Sri-Lanka in the south-west the genus is the most speciose and diverse of the family in the Oriental region. The first description of a larva was Vestalis luctuosa (Burmeister) from Java by Ris (1912), who provided diagnostic drawings of exquisite detail, including the tiny supplementary antennomere following the pedicel (Fig. 36a), noted with approbation by Lieftinck (1965), who illustrated the habitus. Lieftinck (1965), also described a larva of the V. amoena Hagen group, with the species not identified with certainty. Lieftinck notes that the median caudal gill of the amoena group is truncated (Fig. 50) whereas in luctuosa it is acuminate (Fig. 51). In particular he states “A peculiar feature of the antennae... [of all Vestalis] is the presence of a vestigial—rarely incompletely developed—extra joint between the pedicel and the second segment [a lapsus, he means pedicel and scape, since the pedicel normally is the second segment]. This intercalated minute segment is present in all [amoena] individuals examined...”. However, in another lapsus, his illustration (Fig. 13c in Lieftinck 1965) of the antenna shows no trace of this vestigial segment, leading later authors (Rattanachan et al. 2022) to state incorrectly that V. amoena lacks the supplementary third antennomere. I have examined specimens of V. amoena, V. amaryllis Lieftinck (supposition), and V. amnicola Lieftinck, from Brunei (Orr 2001, Orr unpublished data), all belonging to the V. amoena group, and all have the supplementary third antennomere and in consequent 8 segments in total. Lieftinck (1965) also notes how in general build Vestalis larvae are intermediate between the spidery long legged Neurobasis and the stouter Echo larvae. Larvae of the V. amoena group are variously found depending on their habits “among leafy trash in a shady brook”, (Lieftinck 1965), to the underside of stones at the edge of a fast-flowing stream and leaf packs among riffles (Orr 2001). It seems likely that the sylvan V. beryllae Laidlaw breeds in boggy springs among leaf litter as the adults are always to be found in such places (Orr 2001). Other descriptions and illustrations of Vestalis larvae include: V. amoena group, photograph of habitus; V. gracilis (Rambur), description and illustrations of diagnostic structures and habitus with note “usually concealed among vegetation in riffle zones”, (Rattanachan et al. 2022); V. melania Selys, description and illustrations of diagnostic structures and habitus (Fig. 53) with note “found in an unshaded, narrow, montane stream with a sandy substrate and dense marginal and submerged vegetation”, as well as comparisons with other species (Guadalquiver et al. 2022); V. nigrescens Fraser, stated by St Quentin (1973) to be similar to V. luctuosa, with acuminate caudal lamellae, and inhabiting the banks of stony bottomed streams.
The species, essentially alike in general appearance, fall into two categories: those with a truncate median caudal gill (Fig. 50), (amoena group and gracilis) and those with an acuminate central caudal gill (Fig. 51), (luctuosa, melania and nigrescens). There are also differences in the shape of the mask, which tends to be relatively broader apically with shorter, broader premental lobes in luctuosa and perhaps melania and with subtle differences in the form of the premental cleft, about which Lieftinck (1965), who first noted a possible difference, remained sceptical. With good information available for fewer than half the known species, morphology based larval identification will generally depend on locality, with the probability that eight antennomeres with a tiny third segment is positive proof of generic identity.
description: Published as part of Orr, Albert G. W., 2024, A review of present knowledge of larvae of the Calopterygoidea (Zygoptera) of the Oriental realm, including keys to families and known genera, pp. 209-243 in Zootaxa 5497 (2) on page 227, DOI: 10.11646/zootaxa.5497.2.3, http://zenodo.org/record/13618317