Cacopsylla lapponica 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

publication ID	https://dx.doi.org/10.3897/CompCytogen.v13i4.47395
publication LSID	lsid:zoobank.org:pub:32E091B4-4FDF-4FCA-8937-3A83AA387DFB
persistent identifier	https://treatment.plazi.org/id/852BE45B-EDBF-503A-BA01-EF4CAC31553F
treatment provided by	Comparative Cytogenetics by Pensoft
scientific name	Cacopsylla lapponica S. Nokkala & Ch. Nokkala
status	sp. nov.

Treatment

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

Type material.

Holotype: Female; Finland, Utsjoki Ailigas; 69°53'51 ’’ N, 27°03'32 ’’ E; 320 m; 05 Aug 2016; Seppo & Christina Nokkala leg.; above tree line, host Vaccinium uliginosum ; http://mus.utu.fi/ZMUT.TYPE794. Paratypes: 9 females,1male; Finland, Utsjoki Ailigas; 69°53'51 ’’ N, 27°03'32 ’’ E; 320 m; 05 Aug 2016; Seppo & Christina Nokkala leg.; above tree line, host Vaccinium uliginosum ; http://mus.utu.fi/ZMUT.TYPE795 - http://mus.utu.fi/ZMUT.TYPE797. The holotype and paratypes are deposited at the Zoological Museum, University of Turku, Finland.

Description.

Adult coloration resembles that of cohabitating C. myrtilli , but is much paler with dark markings. Wings are very pale yellow and transparent with dark veins ( Fig. 3 View Figure 3 ). Adults are clearly smaller in size ( Fig. 3 View Figure 3 ), the overall length of males being 1.9-2.1 mm (N = 8) and females 2.3-2.5 mm (N = 10) compared to 2.75-3.25 mm of C. myrtilli females ( Ossiannilsson 1992).

Diagnosis.

The most conspicuous difference in external morphology between C. myrtilli and C. lapponica is the length of wings. In C. lapponica , the wing is much shorter than in C. myrtilli ( Fig. 4 View Figure 4 ). In C. lapponica , the wings are just slightly longer than the abdomen, while in C. myrtilli the wings are almost twice as long as the abdomen.

According to the species identification key, the distribution of surface spinules in the s+cs cell in the forewing has been used to separate the closely related species of C. myrtilli and C. ledi (Ossialnnilsson, 1992). In C. myrtilli surface spinules cover the s+cs cell entirely, while in C. ledi the spinules are absent in the apical third of the cell. In C. lapponica ( Fig. 5a View Figure 5 ), the distribution of spinules is similar to that found in C. myrtilli .

Males can also be differentiated by their paramere structure ( Fig. 6 View Figure 6 ). In males of C. lapponica , the thickest region is in the middle of paramere viewed from behind ( Fig. 6a View Figure 6 ), and a similar region is seen in the apical part of paramere in C. myrtilli ( Fig. 6b View Figure 6 ).

Female C. lapponica are easily distinguished from C. myrtilli females by differences in their terminalia structures ( Fig. 7 View Figure 7 ). In C. lapponica , the circumanal pore ring complex is symmetric, oval-shaped, and proctiger is sharply pointed ( Fig. 7a View Figure 7 ), whereas in C. myrtilli , the same structure is clearly asymmetric and the apical part of proctiger is more rounded ( Fig. 7b View Figure 7 ). As shown below, the subgenital plate evenly decreases in width towards the apex in C. lapponica ( Fig. 7c View Figure 7 ), while the width strongly decreased halfway of the plate in C. myrtilli ( Fig. 7d View Figure 7 ). In the side view the subgenital plate differs clearly between the species. In C. lapponica , the upper edge runs quite straight and is curved only near the apex ( Fig. 7e View Figure 7 ), while in C. myrtilli , there is a strong curve already near the middle of the plate ( Fig. 7f View Figure 7 ).

Distribution.

Specimens of C. lapponica were found in three locations at high altitude above the tree line in northern Sweden and Finland (Table 1 View Table ). In all these locations, C. lapponica coexists with C. myrtilli on low growing V. uliginosum plants in low numbers. As an example, in a sample collected on 6.8.2016 in Utsojki, Ailigas at 320 m altitude, there were 252 specimens of C. myrtilli and among them 15 specimens (8 females and 7 males) of C. lapponica , the proportion of C. lapponica being 5.6% of the total. It is obvious, that C. lapponica is a rare alpine species restricted to a high-altitude open habitat.

Etymology.

The name “lapponica” in Latin means "from Lapponia" or “Lapponian” reflecting the restricted distribution of the species to northern Fennoscandia in locations above the tree line.