Winnertzia discreta, Mohrig & Mamaev, 1970

Jaschhof, Mathias & Jaschhof, Catrin, 2020, Reevaluation of species richness in Winnertzia (Diptera, Cecidomyiidae, Winnertziinae), with descriptions of 37 new species from Sweden, Peru and Australia, Zootaxa 4829 (1), pp. 1-72 : 9

Winnertzia discreta group

Diagnosis. Species of the discreta group are distinguished from other Winnertzia in lacking a pectinate claw at the gonostylar apex. The area supposed to bear the claw is extensively covered with microtrichia appreciably larger and denser than ordinary pubescence. Although some of those microtrichia may be almost as large as the individual spines involved in claw formation, they are, as a rule, randomly scattered, not aligned or otherwise clustered. Deviations from this pattern are W. angustistylus and W. rickebasta , in which most of the microtrichia are dispersed while some tend to form small tufts ( Figs 2 , 17 ), or W. pectinulata , in which several particularly thick microtrichia form a sparse row (unpublished observation).

Phylogeny. Both microtrichia and spines are outgrowths of the cuticle without sensory function, so may be regarded as homologous structures whose principal difference is size. Microtrichia are, as the name suggests, very small hairs that form the basal pubescence, while spines, as used here, are the extra-large, stiff components that form the pectinate claws. Since microtrichia and spines differ merely gradually, we do not think there is a fundamental difference between claw-bearing and clawless gonostyli. Hence it is merely a matter of convention whether W. pectinulata is classified either with the discreta group (by arguing that the thick, aligned microtrichia at the gonostylar apex do not qualify as a pectinate claw) or with the solidaginis group (by arguing that the pectinate claw is made of unusually thin, sparse spines). Therefore, we conclude that absence of the gonostylar claw should not be used as an argument for justifying the monophyly of the discreta group. We think it more reasonable to assume that the enlargement of microtrichia on the gonostylar apex is a feature belonging to the ground plan of Winnertzia , for this is the condition found in most other Winnertziini . With that being the plesiomorphous state, pectinate claws probably evolved, and subsequently got lost again, several times independently in Winnertzia .

Species included. The discreta group contains 11 Palearctic species named in the past (asterisks mark species occurring in Sweden): W. amoena Mamaev , W. brachypalpa Mamaev , W. centralis Mamaev , W. discreta Mohrig & Mamaev , * W. discretella Spungis , W. invisibilis Mamaev , W. palpina Mamaev , W. pectinulata Mamaev , W. peramoena Mamaev , * W. rotundata Spungis , and W. triangulifera Mamaev. In addition to this, six new species are described here from Sweden. Extra-Palearctic species belonging to this group are the North American W. rubida Felt (discussed by Jaschhof & Jaschhof (2013: 77) under W. discretella ) and W. warraensis , the first Winnertzia described here from Australia.

Figures

FIGURES 1–6. Male morphology of Winnertzia angustistylus. 1: Genitalia, ventral, holotype. 2: Gonostylus, ventral, paratype. 3: Fourth flagellomere, lateral, holotype. 4: Ditto, medial. 5: Palpus, lateral, paratype. 6: Wing, dorsal, specimen from Södermanland. Scales for 1, 3 and 4, 0.05 mm; for 2 and 5, 0.025 mm; for 6, 0.50 mm. Arrows refer to characters described in the diagnosis.

FIGURES 14–19. Male morphology of Winnertzia pilosistylus (14–16) and Winnertzia rickebasta (17–19). 14: Fourth flagellomere, lateral, paratype. 15: Ditto, medial. 16: Genitalia, ventral, holotype. 17: Ditto. 18: Fourth flagellomere, lateral, holotype. 19: Ditto, medial. Scales 0.05 mm. Arrows refer to characters described in the diagnoses.