Dicranomyia (Dicranomyia) lutea ( Meigen, 1804 )

Starý, Jaroslav & Stubbs, Alan E., 2015, Five species under Dicranomyia (Dicranomyia) mitis (Meigen, 1830) (Diptera, Limoniidae), Zootaxa 3964 (3), pp. 321-334 : 330-332

Dicranomyia (Dicranomyia) lutea ( Meigen, 1804)

Figs 4 , 9 , 14 , 19

Limonia lutea Meigen 1804: 55 (description).

Limonia (Dicranomyia) mitis var. lutea: Edwards 1938: 37 (diagnosis). Dicranomyia lutea: Stubbs 1998a: 23 (key), Fig. (male terminalia).

Diagnosis. Small species. Body colouration yellow to ochreous. Wing clear, with only sometimes feebly indicated pterostigma. Sc1 without any macrotrichia. Two last male tarsomeres long, parallel-sided; tarsal claws with only one tooth fairly distinct. Male terminalia with rostral prolongation of ventral gonostylus truncate close beyond medial spine; rostral spines gently curved, separated at base by less than their own breadth. Female terminalia with cercus shorter than in other species, about two thirds length of tergite 10; space between cerci subequal in width to cercus breadth at base. Wing length 5.5–8.0 mm.

Redescription. Male. Head with grey pruinosity on frons and vertex, yellowed at base, rostrum yellowishbrown. Antenna dark brown, reaching to about anterior margin of prescutum, with flagellomere 1 yellowed proximally. Flagellomeres short-ovoid, gradually narrowed towards apex of antenna, with verticils shorter than respective segments. Palpus yellowish-brown on palpomere 1, otherwise dark brown.

Thorax generally yellow to ochreous. Pronotum ochreous. Prescutum ochreous, sometimes darker medially and yellowed laterally, with thin pale grey pruinosity, scutal lobes darker medially; scutellum paler, mediotergite usually dark brown. Pleuron concolorous with prescutum, darker on katepisternum and paler on dorsopleural membrane. Wing clear except for at most feebly indicated pterostigma (Fig. 19). Sc1 without any macrotrichia. Halter with slightly infuscated knob. Legs with coxae and trochanters yellow. Femora yellow, with slightly darker apical ring. Tibiae yellow, darker on both ends, tarsi darker. Two last tarsomeres rather long, former slightly longer than latter, both straight, parallel-sided, rod-like; tarsomere 4 with longitudinal row of stiff, short, suberect setae on distal half ventrally; setae indistinctly hooked at tip. Tarsal claws shorter than those in D. (D.) mitis and D. (D.) affinis , less than one third length of tarsomere 5, with one well-developed tooth proximal to mid-length, other teeth little-distinct ( Fig. 4 ).

Abdomen brown dorsally, paler ventrally. Male terminalia ( Fig. 9 ): Tergite 9 short, about three times as broad as long, with shallow, rather U-shaped, median emargination at posterior margin and incomplete median suture. Gonocoxite moderately long, about half length of ventral gonostylus. The latter long-ovoid, about twice as long as broad. Rostral prolongation of ventral gonostylus truncate close beyond medial spine. Rostral spines gently curved, close together, separated at base by less than their own breadth.

Female. Resembling male in general appearance, including structure of tarsi and tarsal claws. Female terminalia ( Fig. 14 ): Cercus gently upturned, shorter than in other species treated here, about two thirds length of tergite 10. Space between cerci subequal in width to cercus breadth at base. Genital fork (vaginal apodeme) generally triangular, not reaching to posterior margin of tergite 10. Sternum 9 short, about one third length of tergite 10.

Material examined (33 ♂, 24 ♀). Czech Republic: Moravia: Hrubý Jeseník Mts, Rejvíz (700 m), 17. v.2000, 1 ♀; Horní Údolí nr. Zlaté Hory, 9. vii.1991, 1 ♀; Hrubý Jeseník Mts, Karlova Studánka (900 m), 13. v.1999, 1 ♂, 25. v.1999, 1 ♂, 2 ♀; Hrubá Voda nr. Olomouc, 25. vi.1992, 1 ♀; Grygov, quarries, 16. vi.1994, 2 ♂, 1 ♀; Moravskoslezské Beskydy Mts, Pustevny (1000 m), 26. vi.1985, 1 ♂; Moravskoslezské Beskydy Mts, “Malinová” (700–800 m), 19. vii.1990, 1 ♀, 24. vii.1990, 1 ♀, 22. v.1991, 1 ♂, 24. vi.1993, 1 ♂; Moravskoslezské Beskydy Mts, Prostřední Bečva (500–600 m), 4. vi.1992, 1 ♂, 30. vii.1992, 1 ♀, 18. vi.1993, 1 ♂, 1 ♀, 23. vi.1993, 3 ♂, 10. v.1994, 5 ♂, 1 ♀, 1. vi.1994, 2 ♂, 7. vi.1994, 1 ♂; Moravskoslezské Beskydy Mts, Horní Bečva, “Kladnatá“, 14. vi.1989, 1 ♀; Hostýnské vrchy [hills], “Bernardka” (500 m), 12. vi.1992, 1 ♂; Mohelno, 10. vi.1972, 1 ♂ (all J. Starý leg., all JSO). Great Britain: England: Staffordshire, Alton Towers, 23. vi.1911, 1 ♀; Hertfordshire, Baldock, vi.1918, 1 ♀; Hertfordshire, Letchworth, 8. vi.1928, 1 ♀; Bedfordshire, Barton, 8.–9. vii.1928, 1 ♀ (all F.W. Edwards leg.); Avon Gorge, 18. vi.1908, 2 ♀ (J.J.F.X. King leg.); East Sussex, Frant, 16. vi.1886, 1 ♂; East Sussex, Laughton, 5. vi.1888, 1 ♂, 2 ♀ (all G.H. Verrall leg.); South Devon, Dartmouth, 28.–31. v.1920, 1 ♂, 1 ♀ (F.W. Edwards leg.) (all BMNH). Wales: Flintshire, Ffrith, 7.–9. vi.1919, 1 ♀; Denbighshire, Llangollen, 30. vi.1914, 1 ♀ (all F.W. Edwards leg., all BMNH). Slovakia: Malá Fatra Mts, Biela (700 m), 28. v.1992, 2 ♂; Bielanske Tatry Mts, Tatranská Kotlina, Biela valley (750 m), 26. vi.1977, 1 ♂; Poľana Mts, Kyslinky, “Majerová” (850 m), 18. vi.2003, 1 ♀; Slovenský kras, Zádiel, 12. vi.1982, 1 ♂ (at light); Nová Sedlica env., 10. vi.1996, 1 ♂, 13. vi.1996, 3 ♂ (all J. Starý leg., all JSO).

Discussion. Both D. (D.) lutea and D. (D.) imbecilla are rather similar to each other in their small size and rather pale general appearance. They have overall body colouration mostly yellow to ochreous (pale green to greenish yellow in teneral specimens), restrictedly darker in dry-mounted material, and the wings clear, with at most feebly indicated pterostigma. The males of the two species are best separated on the structure of the tarsomeres and tarsal claws. In D. (D.) lutea the two last tarsomeres are rod-like (much as in the other species except for D. (D.) imbecilla ) and the tarsal claws less than one third the length of tarsomere 5 (as in D. (D.) quadra ), with one well-developed tooth. In D. (D.) imbecilla , these characters are quite different from those of the other species treated here; tarsomere 5 is distinctly shorter than tarsomere 4, somewhat flattened and with a pair of long, unusually stout setae ventrally, and the tarsal claws are about half the length of tarsomere 5, with a single well-developed tooth at base (cf. Figs 4 and 5 ). Male terminalia of D. (D.) lutea have tergite 9 short, about three times as broad as long, and the rostral spines close together, separated at base by less than their own breadth. In D. (D.) imbecilla , on the contrary, tergite 9 is longer, about twice as broad as long, and the rostral spines are separated at base by more than their own breadth (cf. Figs 9 and 10 ). In the female terminalia of D. (D.) lutea , the cerci are shorter than in the other species, about two thirds the length of tergite 10, the genital fork does not reach to the posterior margin of tergite 10, which also is a feature not seen in the other species, and sternum 9 is short, about one third the length of tergite 10. In the female terminalia of D. (D.) imbecilla , the cerci are longer than in D. (D.) lutea , subequal in length to tergite 10, the genital fork extends beyond the posterior margin of tergite 10, which is unique within the species treated here, and sternum 9 is long, more than half the length of tergite 10 (cf. Figs 14 and 15 ).

Ecology. In Great Britain, the species is common in the southern half of England, mainly on well-drained calcareous clay or limestone soils, preferring scrub edges associated with calcareous grassland. A widespread distribution extends over much of Great Britain where non-acid soils are present. Both D. (D.) lutea and D. (D.) mitis can be found together, but the former species is the less restricted one. D. (D.) lutea can occur within woodland, but rarely in numbers, and notably it can occur by shaded streams where D. (D.) quadra also lives. D. (D.) lutea flies from late April to June, and its peak of occurrence is in common with D. (D.) mitis , but D. (D.) lutea may extend into July ( AS).

Distribution. Austria, Germany, Great Britain, Ireland ( Oosterbroek 2014). It should be noted that this species has so far been interpreted as described by Meigen (1818). It is here recorded for the first time for the Czech Republic and Slovakia, but it seems to be widespread throughout Europe.

Figures

FIGURES 1 – 5. T wo distal tarsomeres and tarsal claw (with details of tarsal claw). 1 — D. (D.) mitis (Czech Republic: Bohemia: Šumava Mts). 2 — D. (D.) affinis (Morocco: Rif Mts). 3 — D. (D.) quadra (Czech Republic: Moravia: Hrubý Jeseník Mts). 4 — D. (D.) lutea (Czech Republic: Moravia: Moravskoslezské Beskydy Mts). 5 — D. (D.) imbecilla (Czech Republic: Moravia: Hrubý Jeseník Mts). Scale bar 0.25 mm.

FIGURES 6 – 10. Male terminalia, general view, dorsal (with details of rostral prologation of ventral gonostylus). 6 — D. (D.) mitis (Czech Republic: Bohemia: Šumava Mts). 7 — D. (D.) affinis (Morocco: Rif Mts). 8 — D. (D.) quadra (Czech Republic: Moravia: Hrubý Jeseník Mts). 9 — D. (D.) lutea (Czech Republic: Moravia: Moravskoslezské Beskydy Mts). 10 — D. (D.) imbecilla (Czech Republic: Moravia: Hrubý Jeseník Mts). Scale bar 0.5 mm.

FIGURES 11 – 15. Female terminalia, internal structures, ventral. 11 — D. (D.) mitis (Czech Republic: Moravia: Moravskoslezské Beskydy Mts). 12 — D. (D.) affinis (Morocco: Rif Mts). 13 — D. (D.) quadra (Czech Republic: Moravia: Hrubý Jeseník Mts). 14 — D. (D.) lutea (Czech Republic: Moravia: Moravskoslezské Beskydy Mts). 15 — D. (D.) imbecilla (Czech Republic: Moravia: Hrubý Jeseník Mts). Scale bar 0.5 mm. ce—cerci; gf—genital fork (vaginal apodeme); ifp—infraanal plate; s 9 — sternum 9; t 10 — tergite 10.