Cacopsylla borealis S. Nokkala & Ch. Nokkala

Nokkala, Christina, Kuznetsova, Valentina G., Rinne, Veikko & Nokkala, Seppo, 2019, Description of two new species of the genus Cacopsylla Ossiannilsson, 1970 (Hemiptera, Psylloidea) from northern Fennoscandia recognized by morphology, cytogenetic characters and COI barcode sequence, Comparative Cytogenetics 13 (4), pp. 367-382 : 367

Cacopsylla borealis S. Nokkala & Ch. Nokkala sp. nov.

Type material.

Holotype: Female; Finland, Salla, Tuntsa; 67°18'11"N, 29°16'18"E; 01. Aug. 2019; Seppo & Christina Nokkala leg.; host Ledum palustre ; http://mus.utu.fi/ZMUT.TYPE798. Paratypes: 10 females; Finland, Salla, Tuntsa; 67°18'11"N, 29°16'18"E; 01. Aug. 2019; Seppo & Christina Nokkala leg.; host Ledum palustre ; http://mus.utu.fi/ZMUT.TYPE799. 5 females; Russia, Baikal; 51°54'25"N, 105°04'14"E; July 2007; E. Labina leg.; host Ledum palustre ; http://mus.utu.fi/ZMUT.TYPE800. 6 females; Russia, Vorkuta; 67°30'00"N, 64°02'00"E; 6 Aug. 2013; N. Khabasova leg.; host Ledum palustre ; http://mus.utu.fi/ZMUT.TYPE801. The holotype and paratypes are deposited at the Zoological Museum, University of Turku, Finland.

Description.

Adult coloration resembles C. ledi , but is more brownish with dark markings. Wings are yellowish and transparent with yellowish veins. Males are unknown. Overall length of females is similar to that of C. ledi (2.53-3.04 mm, N = 5).

Diagnosis.

The distribution of the surface spinules in the c+sc cell of forewing in C. borealis ( Fig. 5b ) is similar to spinule distribution in C. ledi . However, C. borealis and C. ledi can be indentified reliably by differences in their external morphology ( Figs 8 - 10 ). A conspicuous difference is found in the forewings, where in clavus, apex and basal wing margin are dark brown in C. borealis ( Fig. 8 ). Typically, on mesoscutum there are four highly pigmented longitudinal stripes in C. borealis , that are completely absent in C. ledi ( Fig. 9 a–b ).

In female terminalia in dorsal view, the circumanal pore ring complex is wider in C. borealis than in C. ledi ( Fig. 9 c–d ). The ventral subgenital plate seen from below narrows evenly towards the rounded apex in C. borealis while in C. ledi the structure is more slender and narrows strongly at first and then more evenly towards the apex ( Fig. 9 e–f ). In C. borealis , the structure of the female terminalia in side view resembles that found in C. myrtilli and is quite different from that found in C. ledi ( Fig. 9 g–h ). The antennae in C. borealis are thicker and shorter than in C. ledi ( Fig. 10 ). Antennae are shortest in C. lapponica and thickness is similar compared to that of C. borealis , while the antennae have equal length in C. myrtilli and C. ledi .

Distribution.

C. borealis forms dense populations in northern Fennoscandia down to latitude 66° (Table 1 .) It is also not uncommon to find mixed populations with C. ledi . It is easily understood as they are both parthenogenetic and live in those populations strictly reproductively isolated from each other. On the other hand, the wide distribution of C. borealis from Western Europe to Lake Baikal in the east suggests that C. borealis is of old origin. In some locations, most specimens in mixed populations living on L. palustre are C. borealis , as in Utsjoki, Ailigas (320 m), while in another location, in Utsjoki, Utsjoki Hietala near the sea level, the proportion of C. ledi is close to 20%. However, in several locations, as in Salla, Tuntsa and Salla, Niemelä, as well as in Kuusamo, Kantojoki and Kuusamo, Sakkojoki all individuals collected were C. borealis . The species C. borealis was found to be quite common in northern Finland. However, the hitherto known distribution of the species in Fennoscandia is restricted to north of latitude 63°.

Etymology.

The name “borealis” which means “north” or “northern” in Latin was given because of the wide Palearctic distribution of the species.

Figures

Figure 5. The distribution of surface spinules in the s + cs cell in the forewing a C. lapponica sp. nov. The distribution of spinules is similar to that of C. myrtilli b C. borealis sp. nov. The distribution of spinules is similar to that of C. ledi.

Figure 8. Comparison of forewing coloration in C. borealis sp. nov. and C. ledi a C. borealis sp. nov., dark brown apex and basal wing margin in clavus b C. ledi, clavus without dark brown markings.

Figure 9. Comparison of morphological details between C. borealis sp. nov. (a, c, e, g) and C. ledi (b, d, f, h). Mesoscutum (a-b) dorsal plate (proctiger) (c-d) subgenital plate, ventral view (e-f) female terminalia in side view (g-h).

Figure 10. Antennae in C. borealis sp. nov., C. lapponica sp. nov., C. ledi and C. myrtilli.