Libellago lineata
Creators: name: Orr, Albert G. W.
name: Dow, Rory A.
name: Steinhoff, Philip O. M.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Chlorocyphidae
Libellago
Libellago lineata

description: Partial description of larva of Libellago lineata (Burmeister)
(Figs 9e, 19a–c)
Material examined: 1 ♂ exuviae, Steam bank vegetation, Lanna Resort, Ban Pong, Hang Dong District, Chiang Mai, Chiang Mai Province, Thailand, 18.75333N, 98.88E, 20 iii 2003, A.G. Orr leg. The identification is based on supposition but size and features of head, antennae and mouthparts and caudal spikes agree sufficiently closely with L. hyalina and confirmed photographs of this species (Figs 19b, c) that we may be sure of its identity.Also L. lineata is the only species in its genus recorded in that stream and in the whole of Chiang Mai province. It is clearly not the syntopic but larger Heliocypha perforata limbata (Selys 1879), (H. p. perforata was described by Xu 2015), or H. biforata (described by Kumar & Prasad 1977).
Habitus: The exuvia studied resembles closely the specimen depicted from Malaysia (Fig. 19a). It is impossible to determine the coloration due to adhering detritus but living specimens from Malaysia (Figs 19b, c) are both very similar to L. hyalina in the form of the head, antennae and caudal spikes but the legs are obviously shorter, the hind femur reaching the middle of S6 (mid S 7 in L. hyalina), and the abdomen slightly more elongate. The caudal spikes are about 55% of the body length, significantly shorter than in L. hyalina, but of nearly identical form. The coloration is unusually dark, especially on the mid and hind tibiae, but the tip of the pedicel is unmarked, as in L. hyalina.
Mouthparts: prementum (Fig. 9e) similar to that of L. hyalina (Fig. 9d) but distinctly shorter and broader; Lateral margins with slightly more extensive recurved spines interspersed with short setae; Anterior median lobe less produced and median cleft shorter terminating in a small, open nearly circular aperture, as in H. biseriata and also illustrated for L. lineata by Fraser (1919). Labial palps very similar to L. hyalina but inner (lower) branch of palpal lobe not strongly hooked. Maxillae and mandibles not noticeably different from L. hyalina.
Remarks: A partial examination of this species both confirms and augments earlier descriptions (Fraser 1919, 1928), and gives some insight into which characters may show intrageneric variation and which might distinguish Libellago from other genera. It is evident that the shape of the prementum varies significantly among congeners, and hence might be less useful than might be wished in distinguishing genera generally. However the caudal spikes are the same general form in L. hyalina (Fig. 18d) and L. lineata (Fig. 19c) although relatively shorter. In L. aurantiaca (Fig. 19d) they are relatively much shorter but still of the same general form, suggesting that shape, rather than relative length is a reliable generic character. The other distinctive feature shared by all three known species of Libellago larvae, and not known in any other chlorocyphid, is the lack of apical pigmentation on the pedicel (L. hyalina, see above; L. lineata see Fig. 19c, L. aurantiaca see Fig. 16d and Ngiam & Ng 2022).
description: Published as part of Orr, Albert G. W., Dow, Rory A. & Steinhoff, Philip O. M., 2024, Descriptions of larvae of four mainly DNA barcode-matched species of chlorocyphids from south-east Asia (Odonata: Chlorocyphidae) with notes on the generic and species level larval identification of Oriental region members of the family., pp. 301-337 in Zootaxa 5486 (3) on pages 327-330, DOI: 10.11646/zootaxa.5486.3.1, http://zenodo.org/record/13210005