Eulachnus blackmani, Kanturski & Qiao & Favret, 2022

Kanturski, Mariusz, Qiao, Ge-Xia & Favret, Colin, 2022, A new species of Eulachnus Del Guercio from China (Hemiptera: Aphididae Lachninae), Zootaxa 5183 (1), pp. 380-389 : 381-387

publication ID	https://doi.org/ 10.11646/zootaxa.5183.1.28
publication LSID	lsid:zoobank.org:pub:CCA2883B-62A2-4001-AD06-E782B2B2E8B4
DOI	https://doi.org/10.5281/zenodo.7074961
persistent identifier	https://treatment.plazi.org/id/9E2D87F6-6270-B44D-FF74-1E117DCC90EF
treatment provided by	Plazi
scientific name	Eulachnus blackmani
status	sp. nov.

Treatment

Eulachnus blackmani sp. nov.

Eulachnus nigricola Pašek View in CoL : Zhang et al. 1999a: 184, Zhang et al. 1999b: 563, Qiao et al. 2002: 104, Fang et al. 2011: 159 ( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 ; Tables 1 View TABLE 1 , 2 View TABLE 2 )

The main morphological characters of the genus Eulachnus (e.g., body shape, antennal segments, URS and tarsi) were detailed by Kanturski et al. (2017), so we here focus only on the most important features of the new species.

Apterous viviparous female – description (n=8)

( Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 ; Tables 1 View TABLE 1 , 2 View TABLE 2 )

Color in life unknown. Pigmentation on slide: head and thorax sclerotized light yellow; ANT yellow except ANT II and basal part of ANT III which are paler; coxae yellow to light brown; femora yellow to light brown with paler proximal and distal parts; fore and middle tibiae yellow with slightly darker proximal and distal parts, III TIBIAE light brown with yellow distal halves; tarsi yellow; dorsal abdominal scleroites and SIPH sclerites yellow; cauda, anal and genital plate yellow ( Figs 1 View FIGURE 1 , 2 View FIGURE 2 ). Morphometric characters: Head with 5–6 pairs of long to very long, thick and stiff dorsal setae with expanded apices, 0.035 –0.100 mm long ( Fig. 2a, b, c View FIGURE 2 ); ratios HW:ANT 0.48–0.56, ANT:BL 0.40–0.41, PT:BASE 0.25–0.32, VI:III 0.78–0.89, V:III 0.57–0.68, IV:III 0.38–0.52. ANT bearing short to medium, thick, rigid setae with expanded and blunt apices. ANT III setae 0.015 –0.040 mm long, LS ANT III: BD III 1.50–2.66. ANT I with 4–5, ANT II with 3–5, ANT III with 7–10 ( Fig. 3a View FIGURE 3 ), ANT IV with 4–6, ANT V with 5–6 setae ( Fig. 3b View FIGURE 3 ). ANT VI with 4 basal, 2 apical and 4 subapical setae ( Fig. 3c View FIGURE 3 ). Rostrum reaching end of hind coxae. URS 0.33–0.36 × ANT III, 0.41– 0.42 × ANT VI, 1.75–2.00 × PT, 0.51–0.56 × BASE and 0.45–0.46 × HT II, without accessory setae ( Fig. 3d View FIGURE 3 ). III FEMORA with 0.027 –0.090 mm long, thick, rigid setae with blunt and expanded apices. III TIBIAE have 0.025 –0.115 mm long, thick, rigid setae with expanded apices. Few setae in the distal part of III TIBIAE always longer than others ( Fig. 3e, f View FIGURE 3 ). HT I with 8–9 ventral setae, HT 0.71–0.81 × ANT III, 0.88–0.93 × ANT VI and 1.11–1.20 × BASE with two very long dorsal setae ( Fig. 3g View FIGURE 3 ). Abdomen membranous, with mostly irregular scleroites of which the spinal ones are bigger and often fused to form larger sclerites ( Figs 1 View FIGURE 1 , 4 a, c View FIGURE 4 ). Setae arising from scleroites short and rather pointed or blunt in the spinal area and longer and with expanded apices in marginal area ( Fig. 2d, e View FIGURE 2 ). Setae are 0.020 –0.050 mm long on ABD TERG I–V and 0.020 –0.080 mm long on ABD TERG VI–VIII. SIPH poriforme with very small sclerite ( Fig. 4b View FIGURE 4 ). ABD VIII with two separate dorsal sclerites, together with 6–8 setae ( Fig. 4c View FIGURE 4 ). Genital plate heart-shaped with 5–8 anterior, 6–8 median and 6–7 posterior setae ( Fig. 4d View FIGURE 4 ).

Alate viviparous female – description (n=2)

( Fig 5 View FIGURE 5 ; Tables 1 View TABLE 1 , 2 View TABLE 2 )

Color in life unknown. Pigmentation on slide: head and thorax sclerotized brown; ANT light brown except basal part of ANT III which are paler; coxae light brown; femora light brown with paler proximal and distal parts; fore and middle tibiae yellow with slightly darker proximal parts, III TIBIAE light brown; dorsal abdominal scleroites and SIPH sclerites brown; cauda, anal and genital plate yellow ( Fig 5a View FIGURE 5 ). Morphometric characters: Head with 6–8 pairs of long and very long, thick and stiff dorsal setae with expanded apices, 0.050 –0.110 mm long; ratios: HW:ANT 0.42–0.48, ANT:BL 0.47–0.48, PT:BASE 0.23–0.30, VI:III 0.60–0.69, V:III 0.50–0.65, IV:III 0.52–0.46; ANT III with 2–3 small and rounded secondary rhinaria in the distal half ( Fig. 5a, b View FIGURE 5 ), ANT IV with one secondary rhinarium; ANT bearing short and rigid setae with expanded and blunt apices. ANT III setae 0.015 –0.030 mm long, LS ANT III:BD III 1.00–2.00.ANT I with 4–5, ANT II with 4–5, ANT III with 7–8, ANT IV with 4–5,ANT V with 3–4 setae. ANT VI with 4 basal, 2 apical and 4–5 subapical setae. Rostrum reaching hind coxae. URS 0.25–0.32 × ANT III, 0.41– 0.46 × ANT VI, 1.75–2.25 × PT and 0.53–0.57 × BASE, without accessory setae. III FEMORA with 0.022 – 0.080 mm long, thick, rigid setae with blunt and expanded apices. III TIBIAE with 0.020 –0.100 mm long, thick, rigid setae with expanded apices. Some outer setae in the middle and distal part of III TIBIAE always longer than others. HT I with 8–10 ventral setae. Abdomen membranous, with mostly irregular scleroites of which the spinal ones are bigger ( Fig. 5d View FIGURE 5 ). Setae arising from scleroites are short and rather pointed or blunt in the spinal area and longer and with expanded apices in marginal area. Setae 0.025 –0.030 mm long on ABD TERG I–V and 0.030 –0.060 mm on ABD TERG VI–VIII. SIPH poriforme with very small sclerite ( Fig. 4b View FIGURE 4 ). ABD VIII with two separate dorsal sclerites, together with 8–10 setae. Genital plate heart-shaped with 20–25 setae over the whole area.

Diagnosis: The new species can be distinguished from all others by the combination of three characters:

• Spinal scleroites larger, often fused, and more irregular than pleural and marginal scleroites;

• Some distal (in alate viviparous females moreover the middle) setae on hind tibiae much longer than others;

• Second segment of hind tarsi with two long dorsal setae, much longer than other tarsal setae;

• Ultimate rostral segments without accessory setae.

Etymology: We are pleased to name the new species in memory of Roger Laurence Blackman, an outstanding aphidologist for many years specialist at the Natural History Museum, London, and one of the collectors of the holotype.

Biology and distribution: Eulachnus blackmani n. sp. is known from China (Hebei, Gansu and Qinghai), but probably is widely distributed, lives on Pinus tabuliformis Carrière and possibly other Pinus species. Sexual morphs are so far unknown. According to the information on the slide, chromosome number is 2n=10.

Material examined: HOLOTYPE. Apterous viviparous female, marked with black circle and indicated with the letter “H” CHINA, Ming Tombs, 31.V.1985, on Pinus sp. , Victor Francis Eastop & Roger Laurence Blackman leg., BM-VFE18193b , RLB3627 (1), NHM PARATYPES. 3 apterous viviparous females, BM-VFE18193b, RLB3627(2). other data as in the holotype, DZUS; 3 apterous viviparous females, Lazikou, Min County, Gansu, 18.VII.1986, on conifer, Zhang Guang-Xue, Zhong Tie-Sen leg., 8488-1(-1-1), NZMC; 1 apterous viviparous, 2 alate viviparous females, Xining City, Qinghai, 12.VIII.1986, on Pinus tabuliformis ( P. tabulaeformis on the slide), Zhang Guang-Xue, Zhong Tie-Sen leg., 8668-1(-1-3), NZMC.

Taxonomic comments

Species of Eulachnus in the Palearctic may be divided into two general groups: the European species (restricted mostly to Europe and the Middle East) and the Asian species common in eastern and south-eastern Asia ( Kanturski et al. 2017). Along with their geographic distribution, they can be recognized by the ultimate rostral segments: the URS in the European species are always without accessory setae, whereas there are two in Asian species. This feature was a key basis for distinguishing E. cembrae from E. pumilae Inouye (Remaudière & Remaudière 1997, Kanturski & Wieczorek 2014). Besides E. pumilae , the two URS accessory setae can also be found in E. dracontos Zhang & Qiao , E. isensis Sorin , E. pinisuctus Zhang, Chen, Zhong & Li , E. piniarmandifoliae Zhang , E. pinitabulaeformis Zhang , E. thunbergi Wilson and E. similialticola Zhang (additionally, E. pumilae and E. piniarmandifoliae are characterized by the lack of dorsal scleroites, as in the European E. cembrae ). In this context, E. blackmani stands out for the absence of accessory setae on the URS, making it more similar to species from the Western Palearctic. European and Asian Eulachnus species may also be distinguished by the pattern of dorsal abdominal scleroites (when present). The European species have two longitudinal rows of scleroites on each of the spinal, pleural and marginal areas, but a reduced number of scleroites on at least one abdominal segment, usually a distal one. Eulachnus nigricola has an especially reduced number of scleroites, those of the spinal area consisting of a single row. The typical Asian species, on the other hand, do not show any reduction, with all rows of scleroites with a similar (and often even larger) number of scleroites. In this context, E. blackmani , with the larger spinal scleroites, seems to be more similar to the European species whose proximal row has fewer scleroites. Additional and detailed morphological differences between E. blackmani and E. nigricola are given in Table 2 View TABLE 2 . Among the European species, E. brevipilosus Börner and E. nigricola are much smaller and have shorter legs than the rest of the species of the so called “ agilis ” group ( Kanturski et al. 2015). The new species also has a shorter body length and shorter legs, distinguishing it from other Asian Eulachnus species, and placing it closer to the species from the European “ brevipilosus ” group. Due to these three morphological features (URS, scleroite pattern and size), it is unsurprising that the Asian E. blackmani was for so long confused for the European E. nigricola .