Psolodesmus, McLachlan, 1870

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 : 226

Psolodesmus

Just two closely related species belong to this genus: one, Psolodesmus mandarinus McLachlan is restricted to Taiwan and the other, P. kuroiwae Oguma to the southern Japanese Yaeyama Islands. The larva of P. mandarinus dorothea Williamson was described in detail by Matsuki & Lien (1978), who also figure details of the prementum of P. mandarinus mandarinus , claiming that small differences in the premental cleft distinguish larvae of the two subspecies. Otherwise there is little difference between them, but those of P. m. mandarinus are described as inhabiting low hills “living in fountain head and upper section of slow streams, but occasionally breeding in artificially made ditches”. The larva of P. kuroiwae was described and illustrated by Watanabe (1984), Ishida & Ishida (1985) and Ishida (1996) and differs very little from P. mandarinus . In all cases the prementum is very broad anteriorly with the anterior processes flanking the central narrow tear-drop cleft touching apically or overlapping, and bearing a single pair of strong setae near the base ( Fig. 34 ). The overall build of the larva is heavy and the short lateral caudal lamellae have a strong row of teeth along the central outer ridge ( Fig. 44 ), with the dorsal and ventral margins smooth (cf Echo ). The central lamella is significantly shorter than the lateral ones and has a long thin, narrowly triangular dorsal guard (also slightly different from Echo in both respects).

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 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).