Calopterygidae, Selys, 1850

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 : 223-228

Family Calopterygidae

The larvae of 11 of the 12 genera present in the region have been described and approximately one third of the 68 species are known but not necessarily described. The larvae of Neurobasis (Sinobasis) anderssoni Sjöstedt from China is unknown and likely to be distinctive. All species are long legged and elongate, but some genera are stouter; in all species the first antennal segment (scape) is greatly enlarged, broad at the base and longer than or as long as the remaining six segments and often longer than the head is wide; intergeneric variation occurs mainly in the form of the prementum and of the caudal gills, which vary greatly in relative length and in structure. We can mostly be confident of generic level classification, but too few species of the pairs of similar genera Atrocalopteryx / Matrona and Vestalis / Vestalaria are known to be sure the keys accurately resolve all species. A distinctive form with strongly angulated postocular lobes described by Fraser (1943) as Caliphaea confusa Hagen may in fact be Echo margarita Selys and another enigmatic larva collected in Nepal cannot at present be assigned to a genus ( Orr & Butler 2024). Almost all species in the family inhabit clear free flowing streams, typically in forest towards the equator and at lower elevations. Measurements (A, B, C, D) used in subsequent key descriptions are indicated in Fig. 27 .

Larva unknown: Noguchiphaea (3 spp.)

Key to genera

1 Premental cleft deep, diamond shaped or ovoid, ratio A/B at least 0.5 ( Figs 28, 29, 30, 31 ); thinly built long legged species; lateral caudal gills at least half length of remainder of body ( Figs 54, 55 )......................................... 2

1’ Premental cleft, ratio A/B: 0.25–0.33 and tear-drop shaped ( Figs 32, 33, 34 , 35, 36, 37 ), or cleft narrow and open anteriorly ( Fig. 38 ); often moderately heavy in build; lateral caudal gills rarely more than half length of remainder of body............... 5

2 (1) Prementum very long and narrow, ratio B/D: 2.2–2.8 and premental cleft deep, ratio A/B: ca 0.6 ( Figs 28, 29 ); single strong seta on each lobe of prementum.............................................................................. 3

2’ Prementum broader and shorter, ratio B/D: 1.6-2 and premental cleft depth ratio A/B ca. 0.5 ( Figs 30, 31 ); two strong setae on each lobe of prementum................................................................................ 4

3 Lateral caudal gills about half length of rest of body; middle gill less than half length of laterals; hindlegs extended just reaching tip of S10. large species (body length excluding antennae and caudal gills 37 mm)............. Matronoides cyaneipennis [endemic to North Borneo over 900m]

3’ Lateral gills about 0.7 length of rest of body; middle gill more than half length of laterals; very slender in build with long spindly legs; hindlegs extended reaching well beyond S10 of abdomen ( Fig. 54 ); widespread in clear streams throughout the region....................................................................................... Neurobasis

4 (2’) Prementum ( Fig. 30 ) elongate, ratio B/D: 1.8–1.9 and cleft boad, ratio C/D: 0.3; anterior lobes of prementum long and narrow (total length from base: width at midpoint = 9.5); abdomen moderately broad; hind femur reaching S6; lateral caudal gill about half length of remainder of body ( Figs 48 , 55 )......................................................... Matrona

4’ Prementum ( Fig. 31 ) shorter (ratio B/D: 1.65) and more solid; cleft narrow, ratio C/D: 0.24 anterior lobes of prementum shorter and broader (total length from base: width at midpoint = 5.6); hind femur at most reaching S5; lateral caudal gill about 0.6 length of remainder of body.................................................................. Atrocalopteryx

5 (1’) Lateral caudal gills, long, narrow, clearly triquetral, slightly more than half length of remainder of body and armed with wellspaced tubercles along margins, with posterior tubercles long and finger-like ( Fig. 42 ); premental cleft short (A/B: 0.24); no inner strong setae on relatively short lobes of prementum ( Fig. 35 )....................................... Archineura

5’ Lateral caudal gills without tubercles, or if tubercles present then less than one third length of remainder of body.......... 6

6 (5’) Lateral caudal gills laminate, foliate and at least one third length of remainder of body ( Fig. 50 ); prementum ratio B/D: 1.37– 1.6. ( Figs 36, 37 )..................................................................................... 7

6’ Lateral caudal gills less than one third length of remainder of body; prementum ratio B/D: 1.1–1.3...................... 8

7 (6) Two strong spines on each lobe of prementum ( Fig. 36 ); depth of premental cleft ratio A/B 0.33 or greater; prementum abruptly expanded anteriorly; lateral gills 0.33–0.36 length of remainder of body ( Fig. 53 ); antennal scape ca 0.8 width of head; antenna with very short segment between pedicel and scape, 8 segmented ( Fig. 36 ).................................. Vestalis [widespread west of Wallace’s line]

7’ One strong spine on each lobe of prementum ( Fig. 37 ); premental cleft ratio A/B less than 0.33; prementum gradually expanded anteriorly; lateral gills 0.46–0.5 length remainder of body; antennal scape ca width of head or longer, antenna lacking short segment between pedicel and scape, 7 segmented..................................................... Vestalaria

8 (6’) Premental cleft long and narrow, lobes of prementum not meeting anteriorly; ratio A/B: 0.33 ( Fig. 38 ); lateral caudal gills very short, no more than 0.25 length of remainder of body ( Fig. 52 ); ovoid, margins smooth, with outer central rib bearing 5–7 well defined denticles ( Fig. 47 ); antennal scape about half total length of antenna ( Fig. 38 )........................ Caliphaea

8’ Premental cleft narrow, pear-drop outline, tips of lobes of prementum touching or overlapping cleft, relatively short, ratio A/B:0.25–0.30 ( Figs 32–34 ); lateral caudal gills ranging from 0.25–0.33 total length of remainder of body.................. 9

9 (8’) Lateral gills smooth, without denticles, elongate ovoid ( Fig. 45 ) or broadly sickle-shaped, about one third length of remainder of body; postocular lobes shallow in outline; one strong setae on lobes of prementum ( Fig. 32 ).................... Mnais

9’ Lateral gills bearing denticles on central outer rib and sometimes on margins..................................... 10

10 (9’) Postocular lobe shallow in outline with small tubercle ( Fig. 56 ) (but see note on Fraser 1924); lateral caudal gills about three times as long as broad with denticles along dorsal and ventral margins and small tubercles on outer central rib ( Fig. 43 ). Echo [Sumatra, Peninsular Malaysia, eastern Himalayas, Myanmar, Thailand and southern China]

10’ Postocular lobe well rounded in outline with small tubercle; lateral gills ca 0.33 times length of rest of body only outer central rib of lateral gills with very strong denticles; margins smooth ( Fig. 44 )................................. Psolodesmus [ Taiwan and nearby islands]

Figures

FIGURES 27–34. 27. Prementum of Calopterygidae showing measurements used in family key (based on Calopteryx japonica, redrawn from Miyakawa 1983). 28. Neurobasis chinensis, prementum and left labial palp (redrawn from Lieftinck 1965). 29. Matronoides cyaneipennis, prementum and labial palps (ventral view). 30. Matrona basilaris, prementum (dorsal view, drawn from Wang et al. 2017). 31. Atrocalopteryx atrata, prementum (dorsal view, redrawn from Miyakawa 1983). 32. Mnais tenuis, prementum (dorsal view, redrawn from Matsuki & Lien 1977). 33. Echo uniformis, prementum and left labial palp dorsal view (redrawn from Lieftinck 1965). 34. Psolodesmus mandarinus, prementum (dorsal view, redrawn from Matsuki & Lien 1978).

FIGURES 52–56. 52. Caliphaea angka, habitus (based on Yang et al. 2021). 53. Vestalis gracilis, habitus (redrawn from Rattanachan et al. 2022). 54. Neurobasis chinensis, habitus (original drawing). 55. Matrona basilaris, habitus (drawn from Wang et al. 2017). 56. Echo uniformis, habitus (redrawn from Lieftinck 1965).

FIGURES 35–41. 35. Archineura incarnata, prementum (dorsal view, drawn from Yang et al. 2022). 36. Vestalis gracilis, prementum (dorsal view) and right antenna with supplementary antennomere between pedicel and scape (a) arrowed (redrawn from Rattanachan et al. 2022). 37. Vestalaria venusta: prementum (dorsal view) and right antenna (drawn from Wang et al. 2017). 38. Caliphaea angka: prementum (dorsal view) and right antenna (drawn from Yang et al. 2021). 39. Heliocypha biseriata, frontal view of labrum showing dorsal and ventral sections and ‘moustache’ of long, heavy setae on the latter (from Orr et al. 2024). 40. Heliocypha biseriata: details of labial palp in relation to prementum (a) dorsal view—base of movable hook dashed to reveal palpal lobe beneath and open base of premental median cleft arrowed, (b) frontal view, (c) inner view (from Orr et al. 2024). 41. Heliocypha biseriata, detail of fore tarsus with pectinate setae magnified (from Orr et al. 2024).

FIGURES 42–51. 42. Archineura incarnata: caudal gills; left lateral above, median below (drawn from Yang et al. 2022). 43. Echo modesta: caudal gills; left lateral above, median below, with baso-dorsal shield arrowed (original illustration). 44. Psolodesmus mandarinus, dorsal view of caudal gills, with baso-dorsal shield of median gill arrowed (redrawn from Matsuki & Lien 1978). 45. Mnais andersoni, left lateral caudal gill with upper margin of median gill visible; baso-dorsal shield of median gill arrowed (original illustration). 46. Mnais gregoryi: caudal gills; left lateral above, median below, with baso-dorsal shield arrowed (drawn from Yang et al. 2021). 47. Caliphaea angka: caudal gills; left lateral above, median below (drawn from Yang et al. 2021). 48. Matrona basilaris: caudal gills; left lateral above, median below (drawn from Wang et al. 2017). 49. Vestalaria venusta: caudal gills; left lateral above, median below (drawn from Wang et al. 2017). 50. Vestalis amoena group: caudal gills; left lateral above, median below (redrawn from Lieftinck 1965). 51. Vestalis melania: caudal gills; left lateral above, median below (redrawn from Guadalquiver et al. 2022).