Scolioneura vaccinii Smith & Eiseman, 2015

Smith, David R., Eiseman, Charles S., Charney, Noah D. & Record, Sydne, 2015, A new Nearctic Scolioneura (Hymenoptera, Tenthredinidae) mining leaves of Vaccinium (Ericaceae), Journal of Hymenoptera Research 43, pp. 1-8 : 3-6

Scolioneura vaccinii Smith & Eiseman sp. n.

Figs 1-7 , 8-9

Description.

Female: Length, 3.0 mm. Antenna black; ventral surface, especially antennomeres 3-5 paler, dark orange. Head black; mandible reddish brown with apex black; palpi whitish. Thorax black. Legs yellowish with coxae and fore- and midtrochanters black; hind trochanter yellowish apically. Abdomen reddish brown with segments 1-3 and 9 black, tergite 4 slightly darker than 5-8; sheath black. Wings uniformly hyaline, veins and stigma black. Head and body smooth, shiny, without sculpture except for a few punctures at apex of mesoscutellum and very fine meshlike microsculpture on mesonotal lateral lobes. Head and thorax with short, fine white pubescence.

Antennal length 1.3 × head width; 3rd antennomere 1.5 × length of 4th antennomere and 3.5 × longer than apical width; 4th antennomere 2 × longer than apical width (Fig. 3 ). Eyes slightly converging below; lower interocular distance about 1.2 × eye height (Fig. 4 ). Distances between eye and hind ocellus, between hind ocelli, and between hind ocellus and posterior margin of head as 1.0: 0.9: 0.7. Postocellar area about 2 × broader than long. Genal carina present. Forewing with first cubital crossvein absent, vein 2A+3A turned up at apex, almost meeting 1A; hind wing with cell R closed, anal cell present, cells Rs and M absent. Cenchri about as far apart as breadth of one. Hind basitarsomere subequal to length of remaining tarsomeres combined. Tarsal claw without inner tooth, with large, acute basal lobe. Tarsal pulvilli absent on hind tarsomeres 1 and 2, present only on hind tarsomeres 3 and 4 (Fig. 6 ). Sheath in lateral view straight above, rounded below, with long curved hairs (Fig. 7 ); from above broad, parallel sided and rounded at apex. Entire lancet not examined; apex protruding from sheath (Fig. 7 ) with rather deep, rounded serrulae.

Male: Unknown.

Prepupa: White to yellowish with slightly darker head and lateral and dorsal lines; eyespot and apex of mandible black (Fig. 8 ). Abdominal segments apparently with 3 dorsal annulets; apical tergum rounded at apex.

Holotype.

Female, labeled "Washington, Pierce Co., Tacoma, Point Defiance, 13.VIII.2013, em. 22.IV.2014, C. S. Eiseman, ex Vaccinium parvifolium , #CSE 1092." Altitude ~60 m. Deposited in the National Museum of Natural History, Smithsonian Institution, Washington, DC.

Other specimens.

Three specimens were examined that appear identical to S. vaccinii , but all have a black abdomen. The color could vary, especially in the western mountains where melanic forms of some species occur, e.g., Paracharactus montivagus (Cresson, 1880) and Lagonis nevadensis (Cresson, 1880) ( Smith 1969). However, we prefer to base the species on the reared specimen and, because of some doubts, not include the darker specimens in the type series. The data are as follows: WASHINGTON: Whatcom Co., Mt. Baker Ski area, VIII.2.1972, W. J. Turner,W. B. Garnett, collectors (altitude ~1,100-1,550 m) (1 ♂), same but additional label "dry ice Malaise Trap" (1 ♂); Skam. Co., 42 mi S.E. Randle, USFS Rt. N84, VII.29.1972, dry ice Malaise trap, W. J. Turner, W. B. Garnett collectors (altitude ~1,400 m) (1♀). All from the Washington State University collection, Pullman, Washington. The males are similar in color and structure to the female.

Host.

Adult reared from leaf mine in red huckleberry, Vaccinium parvifolium Sm. ( Ericaceae ). Sawfly larvae, probably also this species, found in leaf mines of V. membranaceum Douglas ex Torr.

Etymology.

Based on the genus name of the host plant, Vaccinium .

Discussion.

This species is characterized by the short antennae, about 1.3 × the head width; lower interocular distance slightly longer than eye height; mostly reddish-brown abdomen; absence of the first cubital crossvein in the forewing; presence of pulvilli on only hind tarsomeres 3 and 4; and smooth, shiny mesoscutellum with only a few punctures on the posterior margin.

Liston (2007) separated S. tirolensis from S. betuleti and S. vicina as follows: In S. tirolensis the leg color tends to be darker (but highly variable); first cubital crossvein present, though faint; shorter antenna, about 1.5 × head width; third antennomere 3.5 × as long as apical width; third antennomere about 1.5 × as long as fourth. In S. betuleti and S. vicina , the leg color is lighter; first cubital crossvein absent; antennae longer, 2 × the head width; and the third antennomere is 5-6 × as long as its apical width and only slightly longer than the fourth. Scolioneura vaccinii is closer to S. tirolensis , sharing the short antennae, but S. vaccinii differs by the absence of the first cubital crossvein, even shorter antennae, presence of pulvilli only on hind basitarsomeres 3 and 4, the smooth, shiny mesoscutellum, and the mostly reddish-brown abdomen. In S. tirolensis , the first cubital crossvein is present, pulvilli are present on hind basitarsomeres 1-4, the mesoscutellum is densely punctate with punctures more numerous on the posterior half, and the abdomen is usually black.

Scolioneura hyrcana was not examined, but Benson (1968) separated it from the European species by the enlarged eyes, which are strongly converging below with the lower interocular distance much less than the eye height, and by the presence of tarsal pulvilli only on the two apical tarsomeres. Scolioneura vaccinii shares the presence of pulvilli only on hind basitarsomeres 3 and 4, but differs by the smaller eyes which are farther apart than the eye height.

Life history notes.

Larvae are solitary and form simple, more or less full-depth blotch mines (Fig. 9 ), each completing development within a single leaf as is typical of Fenusini . Completed mines occupy 3.5 to 8.5 cm2, with smaller leaves being entirely mined out. Frass is in the form of discrete, elongate fecal pellets, up to about 0.4 mm by 0.2 mm, which are scattered through the mine at random. When mature, the ~7.0 mm larvae exit their mines and burrow into the ground to overwinter.

Leaf mines on Vaccinium parvifolium and V. membranaceum containing sawfly larvae were first noted from 4 to 10 October 2012, to the south of Mount Rainier (Pierce Co.) and at several locations on the Olympic Peninsula (Clallam, Jefferson, and Grays Harbor counties). The type specimen was reared from a larva found mining a V. parvifolium leaf on 13 August 2013. Since all collected larvae overwintered in soil, there is currently no indication of more than one generation per year. The April emergence date for the type specimen is undoubtedly abnormally early, due to the prepupa having been exposed to artificially warm temperatures. The other known specimens were trapped as adults between 29 July and 2 August, consistent with a single generation emerging in early summer and giving rise to larvae that mine from August to October.

Vaccinium plants were searched in northern Idaho in late September 2012 and in northern California in October 2012, but no leaf mines were found. Similar mines found on Rhododendron menziesii Craven ( Ericaceae ) along Boulder Creek in Bonners Ferry, Idaho on 28 September 2012 possibly were made by the same or a related species. Only a few examples were found, and all were empty.

The 2012 collections yielded four braconid wasps, which emerged 18-27 November 2012 and 4-8 May 2013. The 2013 collection yielded one more, which emerged on 7 September. All had spun elongate, pale brown cocoons, 5 mm long by 1 mm wide, inside the leaf mines (Fig. 10 ). All five braconids belonged in the genus Shawiana van Achterberg (Fig. 11 ). Two described species in this genus are known from the Nearctic, both in the eastern United States. Shawiana metalli (Muesebeck) is a parasitoid of Metallus rohweri MacGillivray; S. phyllotomae (Muesebeck) was introduced from Europe to control Heterarthrus nemoratus ( Fallén), and is also recorded from Fenusa pumila Leach ( Muesebeck 1932, Marsh 1979). All of these hosts, like those of most Palearctic species, are leaf-mining sawflies ( Achterberg 1983). Three of our Shawiana specimens are deposited in the Canadian National Collection of Insects, Arachnids and Nematodes, Ottawa, Ontario.

Figures

Figures 1 - 7. Scolioneura vaccinii. 1 Dorsal 2 Lateral 3 Antenna 4 Head front 5 Head dorsal 6 Hind tarsus 7 Sheath, lateral.

Figures 8 - 11. 8 Scolioneura vaccinii, prepupa 9 Leaf mine of S. vaccinii 10 Cocoon of Shawiana sp. in leaf mine of S. vaccinii 11 Shawiana sp., lateral.