Anisopleura, Selys, 1853

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, Zootaxa 5497 (2), pp. 209-243 : 233

Anisopleura

This largely montane genus is confined to northern parts of the Oriental realm where eleven species are recognised from the eastern Himalayas, through northern Myanmar, Thailand and Indochina to southern China.

The first account of larvae the genus was provided by Needham (1911) who described and illustrated presumed Anisopleura comes Hagen , his identification being based on examination of the venation of the as yet unexpanded wing and is consistent with present knowledge. Details of the habitus and labial palp are figured and this information was largely repeated in Needham (1930). Fraser (1929a) figured the habitus and mask of A. subplatystyla Fraser , both apparently fairly accurately, but he unaccountably noted in the legend a lack of ventral abdominal gills, which is quite wrong. Kumar & Prasad (1977a) describe and figured the larva of A. lestoides Selys in detail and although the artwork is somewhat stylised it appears accurate in essentials. Keetapithchayakul et al. (2024) described and figured the rather atypical A. furcata Selys ( Fig. 60 ). This was the first modern, detailed description and depiction of a larva of the genus.

Larvae of the genus are distinguished by several characters; the antennae are relatively short, being shorter than the length of the head from the occipital margin to the base of the labrum ( Fig. 63 ); the labrum, frons and vertex typically bear numerous small low tubercles, sparse or absent in other Euphaea and Bayadera , which, in A. furcata are elongated giving the head a strongly warty appearance. Similar but differently arranged structures are also present on a larva suspected to be A. bipugio Hämäläinen & Karube , the probable nearest relative of A. furcata , but otherwise the tubercles in this species show a degree of development unique in the genus as far as is known. In known species the outer edge of the mandibles bears one or two long spurs, as opposed to more numerous groups of smaller teeth in Euphaea and Bayadera . The inner apical process on the labial palp is short and adpressed or strongly reduced ( Fig. 74 ), a condition rare in other genera. The postocular lobes are shallow and the habitus is comparatively slender, tapering caudad ( Fig. 63 ). There are 2–4 strong spines on the genae below the eye margin. The caudal gills are elongate and evenly tapered to a long filament (a condition not known in Bayadera ). Male genital apophyses (known in detail only in A. furcata ) are moderately well developed, serrate ventrally and just overlying S10, but larger than in Euphaea and not large and sausage like as in known Bayadera .

Larvae of Anisopleura have been found in a variety of small stream habitats from 900–1600m in Bhutan ( Rasaily et al. 2021) including open, disturbed places with dense ground vegetation; those of A. furcata were collected from under stones at the headwaters of clear streams with forest cover from 1100–1200m. They occurred in places of torrential flow and lower gradient trickles Keetapithchayakul et al. (2024), including sites where Cryptophaea saukra Hämäläinen occurs. Similarly Kumar & Prasad (1977a) report the larvae of A. lestoides in rocky hill streams with swift water, sometimes together with Bayadera sp. Keetapithchayakul et al. (2024) report low level infestations by phoretic chironomid larvae on A. furcata (see Boonsoong 2016).

Figures

FIGURES 57–60. 57. Dysphaea gloriosa, habitus (drawn from Nguyen et al. 2024). 58. Bayadera strigata, habitus (drawn from Yang & Orr 2024). 59. Euphaea decorata, habitus. (drawn from Xu 2017). 60. Anisopleura furcata, habitus (drawn from Keetapithchayakul et al. 2024).

FIGURES 61–66. 61. Dysphaea gloriosa: detail of spines on genae and postocular lobe; underside (left), upperside (right) (modified from Nguyen et al. 2024). 62. Heterophaea barbata: dorsal view of head, showing (a) outer mandibular spines (b) genal spines partially visible and (c) right antenna (from Orr & Hämäläinen 2024). 63. Anisopleura subplatystyla, dorsal view of head (original drawing). 64. Bayadera strigata, dorsal view of head (drawn from Yang & Orr 2024). 65. Euphaea decorata, dorsal view of head. (drawn from Xu 2017). 66. Bayadera strigata, left labial palp with detail showing wavy outer margin of outer process of palpal lobe (arrowed), (drawn from Yang & Orr 2024).

FIGURES 67–74. 67. Anisopleura subplatystyla, caudal gills dorsal view (original drawing). 68. Bayadera strigata, caudal gills dorsal view, (drawn from Yang & Orr 2024). 69. Euphaea decorata, caudal gills dorsal view (drawn from Xu 2017). 70. Euphaea superba, caudal gills dorsal view (redrawn from Wu et al. 2017). 71. Bayadera strigata: male genital apophyses; ventral (left), right lateral (right), (drawn from Yang & Orr 2024). 72. Euphaea decorata, male genital apophyses; ventral view (drawn from Xu 2017). 73. Euphaea superba, terminal processes of palpal lobe ventral view (movable hook truncated), (redrawn from Wu et al. 2017). 74. Anisopleura furcata, left labial palp showing terminal processes of palpal lobe, dorsal view (redrawn from Keetapithchayakul et al. 2024).