Essigella sorenseni, Thery, Thomas, Kanturski, Mariusz & Favret, Colin, 2018

Thery, Thomas, Kanturski, Mariusz & Favret, Colin, 2018, Molecular data and species diagnosis in Essigella Del Guercio, 1909 (Sternorrhyncha, Aphididae, Lachninae), ZooKeys 765, pp. 103-122 : 107-109

Essigella sorenseni sp. n. Figs 1f, 3a

Holotype.

viviparous aptera, USA, California, Sonoma Co., 38.534°N 123.276°W, 02.vii.2013, on Pinus muricata , T. Théry & C. Favret leg. (QMOR). Paratypes. 14 viviparous apterae, same data than holotype, specimens on 14 slides (QMOR, CTT); 3 viviparous apterae, California, Mendocino Co., 38.984°N 123.696°W, 03.vii.2013, on Pinus muricata , T. Théry & C. Favret leg., specimens on 3 slides (QMOR, CTT); 6 viviparous apterae, California, Mendocino Co., HWY 1, 5 km of Albion, Little River Road, 23.vii.1977, on Pinus muricata , 77G52, J. T. Sorensen leg., specimens on 3 slides (2 + 2 + 2) EMEC); 13 viviparous apterae, California, Humbodlt Co., nr Little River State Beach, 17 km N Arcata, HWY 101, 04.vii.1978, on Pinus muricata , 78G3, J. T. Sorensen leg., specimens on 4 slides (4 + 4 + 4 + 1) (EMEC).

Diagnosis.

Like species of the E. californica complex and E. pini , E. sorenseni sp. n. has its 3rd and 4th abdominal dorsal terga usually bearing six setae. It can be distinguished from E. patchae by the presence of spinules on the URS (absent or faint in E. patchae ; Fig. 2b, d); from E. pini by a relatively elongate URS with subparallel lateral margins (URS with margins rounded and convergent at base in E. pini ; Fig. 2a, c); from E. domenechi sp. n. and E. gagnonae sp. n. with the following characters: usually pro- and metatibiae conspicuously darkened with mesotibiae always lighter, metafemora darkened (tibiae concolorous, metafemora pale in E. domenechi sp. n., concolorous or with pro- and metatibiae slightly darkened with mesotibiae lighter, metafemora pale in E. gagnonae sp. n.); width of head between eyes = 353.6 ± 15.3 (300.7 ± 14.2 for E. domenechi sp. n., and 289.0 ± 13.3 for E. gagnonae sp. n.); ratio of 3rd / 5th antennal segments> 1.6 (<1.6 for E. domenechi sp. n. and E. gagnonae sp. n.); overall pubescence medium-sized to long with average length of the longest dorsal setae of metafemora = 51.2 ± 10.7 (29.7 ± 4.2 for E. domenechi sp. n., and 59.8 ± 9.8 for E. gagnonae sp. n.); average length of the longest ventral seta of metafemora = 54.4 ± 5.6 (32.6 ± 4.5 for E. domenechi sp. n., and for 43.1 ± 5.4 for E. gagnonae sp. n.); average length of the longest dorsal seta of metatibiae = 76.4 ± 15.8 (44.0 ± 8.1 for E. domenechi sp. n., and 85.7 ± 10.8 for E. gagnonae sp. n.); average length of the longest ventral seta of metatibiae = 67.7 ± 12.0 (37.5 ± 7.0 for E. domenechi sp. n., and 49.4 ± 9.5 for E. gagnonae sp. n.); average length of the longest frontal setae = 53.4 ± 11.9 (32.6 ± 7.5 for E. domenechi sp. n., and for 58.7 ± 8.3 E. gagnonae sp. n.); average number of setae of the genital plate = 31.6 ± 1.7 (22.0 ± 2.1 for E. domenechi sp. n., and 23.6 ± 2.1 for E. gagnonae sp. n.). Essigella sorenseni sp. n. is for now morphologically not distinguishable from E. californica , the latter being highly variable, nor from E. hoerneri . E. sorenseni sp. n. can be separated from E. californica , E. domenechi sp. n., E. gagnonae sp. n., and E. hoerneri with the DNA characters shown in Table 3.

Description.

Viviparous apterae (prepared specimens): body with a yellowish tegument more or less darkened at joints depending on the specimens, with conspicuous and pigmented scleroites. Legs usually with pro- and metatibiae conspicuously darkened, much darker than body and mesotibiae. Antennae pale, the 5th, the 4th and the apical third part of the 3rd segment darkened. URS elongated, with lateral margins subparallel, bearing rows of spinules. Overall pubescence medium-sized to long, dorsal setae of appendages incrassate, ventral ones acute, in specimens with very long dorsal setae on metafemora and metatibiae (> 100 µm), these setae not acute or seemingly acute but still incrassate (Fig. 3a), the setae sometimes curved at base. Terga of abdominal segments 3 and 4 with six dorsal setae. Genital plate with 29-34 setae (31.6 ± 1.7) (n = 10). Cauda obvious but not protruding, apically rounded, slightly turned upward. BL: 1900-2300 (2200 ± 110) (n = 21). HWE: 322.3-376.1 (353,6 ± 15.3) (n = 17), LAIII: 207.5-256.3 (233.6 ± 12.8) (n = 25), LAIV: 98.3-130.0 (112.2 ± 7.1) (n = 34), LAV: 120.1-139.8 (127.9 ± 4.7) (n = 23), LPRIV: 19.9-27.8 (24.1 ± 1.8) (n = 28), LPRV: 17.4-23.4 (19.5 ± 1.5) (n = 21), LPT: 11.6-15.7 (13.8 ± 1.4) (n = 21), LURS: 74.1-86.4 (80.5 ± 3.2) (n = 21), LMF: 702.3-927.8 (810.8 ± 58.9) (n = 26), WMF: 87.5-128.9 (103.1 ± 11.3) (n = 36), LMT: 1064.2-1450.4 (1233.4 ± 95.1) (n = 26), WMT: 49.5-76.0 (55.1 ± 5.1) (n = 37), WS: 39.0-44.6 (41.4 ± 1.7) (n = 22), LMB: 118.5-140.3 (130.3 ± 6.4) (n = 38), LMD: 183.4-212.5 (198.1 ± 7.9) (n = 34), LFS: 31.9-82.7 (53.4 ± 11.9) (n = 25), LDMFS: 34.2-79.4 (51.2 ± 10.7) (n = 45), LVMFS: 43.4-66.0 (54.4 ± 5.6) (n = 44), LDMTS: 47.7-113.8 (76.4 ± 15.8) (n = 46), LVMTS: 45.9-92.2 (67.7 ± 12.0) (n = 45).

Comments.

USA, California, on Pinus muricata D. Don, known from Humboldt, Mendocino, and Sonoma counties (type series), but probably present everywhere on the coastal range in California where P. muricata occurs. This species corresponds to the E. californica population living on P. muricata (cluster H1) shown in Théry et al. (in press).

Etymology.

This species is dedicated to John T. Sorensen, aphid specialist who eminently revised the genus Essigella in 1994, for his advice and hospitality accorded to the authors (TT and CF) in California.