Caliprobola speciosa (Rossi, 1790):285

C. speciosa is classified as endangered and is known from a few sites in southern England (Shirt, 1987). This species is also regarded as endangered in Spain (Marcos-Garcia, 2006).

Caliprobola speciosa (Rossi, 1790).

Rossi, P. (1790) Fauna Etrusca. Sistens insecta quae in provinciis Florentina et Pisana praesertim collegit. Vol. 1, 272 pp.; vol. 2, 348 pp., 10 pls. Masi, Liburni [=Livorno].

Flowers visited by adults: white umbellifers; Caltha, Crataegus, Rorippa, Rubus, Sorbus aucuparia, Tamarix (Speight 2010).

The flight period of this species is from May to mid July, with peak at beginning June (Speight 2010).

C. speciosa ranges from Denmark and Poland south to the Pyrenees and northern Spain; Britain (southern England) east through central Europe (plus northern Italy and northern parts of the former Yugoslavia) into Turkey and European parts of Russia and on into Asia as far as Eastern Siberia (Speight, 2010).

Males fly around, hover between and settle close to, the roots of senescent Castanea, Fagus or Quercus in the sun, settling on bare ground, on the sawdust of cut stumps, or on vegetation (e.g. Pteridium) in the vicinity. Both sexes visit the flowers of small trees and low-growing plants. Can be found away from forests, feeding at flowers growing on exposed riverbed gravels or in adjacent fields, along large rivers with galley forest, in situations with either alluvial softwood, such as Salix alba or Populus, or with hardwood such as Fraxinus/Carpinus/Quercus. The species appears to use these riverine biotopes as corridors to move between forests. An alternative explanation would be that one or more of these trees provides an alternative host for the larvae, but there is so far no evidence for this and the adults cannot be found investigating trunk bases of these trees as they do Castanea and Fagus. C. speciosa visits the damp mud of drying stream beds or drying puddles on tracks, usually in the shade, on hot afternoons, to drink (Speight 2010).

Preferred environment: forest; deciduous forest (Castanea, Fagus, Quercus pedunculata, Q. pubescens) and evergreen oak forest (especially Q. suber forest maintained for cork production) with overmature and senescent trees (Speight 2010).

Larva of C. speciosa was described and figured by Rotheray (1991) and illustrated in colour by Rotheray (1993), from larvae collected from wet, decaying roots of Fagus stumps. It has also been reared from larvae collected from Fagus and Quercus pedunculata stumps/roots/rot-holes by other authors. For instance, Dussaix (2005a) reared the species from material in a moist, trunk-base cavity in Quercus. Distinguished from larvae of related genera in the keys provided by Rotheray (1993).

Third instar larva (from Rotheray 1991).

Overall appearance. Larva with internal mouthparts, lacking hooks on the thorax and having an anal segment with a non-retractile section between lappet pairs 2 and 3 of about 75% of the length of the thorax and abdomen minus the anal segment.

Length. 20 mm + 14 mm for anal segment; width: 4.5 mm; subcylindrical, truncate anteriorly, elongate and tapering posteriorly; mandibles and mandibular lobes internal; base of lateral lips with broad setae, tip with fine setae; vestiture of short (up to 0-06 mm) fine setae, setae becoming longer (0-08 mm) towards posterior of larva; long setae (0-2 mm) in two dorso-lateral rows encompassing sensilla 7-8; anterior fold of prothorax with broad (>75% of anterior fold) spicule band comprising >5 rows; spicules extending posteriorly onto folds between sensilla 4-5, 6-7 and 8; mesothorax with two groups of spicules anterior to sensilla 4 and 5, anterior spiracles present, antero-ventral margin of metathorax with two groups of spicules; prolegs present on mesothorax and first six abdominal segments; crochets multiserial, six-eight large primary crochets; crochet arrangement gradually changing from posterior penellipse (i.e. crochets complete around posterior margin of the proleg) on abdominal segment one to lateral penellipse (i.e. crochets complete on the outer margin) on abdominal segment 6; dorsal section abdominal segment 7 extending over anal segment with sensilla 2, 3 and 4 above anal opening; anal segment extended to about 75% length of thorax and first seven abdominal segments; three pairs of lappets with section between lappet 3 and 2 longest (about six times as long as section between lappets one and two; third pair of lappets about twice as long as first two pairs (0-24 mm); prp: length: 0-76 mm; width: at base 0.16 mm, at tip, 0-22 mm; pale brown and shining; three pairs of spiracular slits.

Material examined. Denny Wood, New Forest, Hampshire: 16 May 1989, two puparia (bred); 18 May 1989, four larvae; 10 March 1990, six puparia (bred), all collected as larvae from wet, decaying roots of Fagus stumps.

The larva of C. speciosa has apparently not been described previously. However, Girschner (1884) briefy described the puparium from larvae collected in the rotten wood of a Fagus stump. Like the Criorhina larvae described here, the larva of C. speciosa was also found underground in wet, decaying roots of Fagus stumps around which males frequently patrolled and on which females were
seen to alight. The larva of C. speciosa can be separated from other syrphid larvae having internal mouthparts, by the absence of hooks on the prothorax and the long extension between lappet pairs 2 and 3 on the anal segment.