On some Ctenarytaina species (Hemiptera, Psylloidea) from Gunung Kinabalu (Malaysia, Sabah)

Gunung Kinabalu is famous for its exceptionally diverse fauna and flora, rich in endemism. An example is the psyllid genus Ctenarytaina that is represented by four, apparently endemic species. Here two new Ctenarytaina species, C. lienhardi sp. nov. and C. smetanai sp. nov., are described from Gunung Kinabalu. The new taxa are diagnosed, illustrated and their relationships to other species in the genus are discussed. Ctenarytaina daleae Burckhardt is redescribed. The species develops on Leptospermum species (Myrtaceae) and not Syzygium as previously suggested.


Introduction
Gunung (=Mount) Kinabalu, with an elevation of around 4100 m, is the highest mountain between the peaks of the eastern flank of the Himalaya in Burma and Mount Wilhelm in Papua New Guinea. It is famous for its exceptionally diverse flora, rich in endemism. The lower slopes were originally covered in lowland dipterocarp forest, most of which has disappeared through human activities. The lowland and montane forests up to about 2500 m altitude are characterised by Oriental floral elements. At altitudes above 2500 m, plant taxa shared with the Himalayan (e.g. Ericaceae) and Australian floras (e.g. Myrtaceae) become more dominant (Cockburn 1978;Corner 1978;Beaman and Beaman 1990). Similar but less well-documented relationships can also be found in phytophagous insects such as the phloem feeding, generally host specific psyllids. This group of Sternorrhyncha includes over 4000 described species worldwide. It is most species-rich in the tropics and south temperate regions .
Fifteen psyllid species have been reported from Gunung Kinabalu. Four Paurocephala species (Liviidae, Liviinae) are associated with species of Pterospermum (Malvaceae), Artocarpus and Ficus (Moraceae) (Mifsud and Burckhardt 2002). They are characteristic Oriental taxa. The other 11 species are members of the subfamily Spondyliaspidinae (Aphalaridae) and are associated with Myrtaceae. They belong to the genera Boreioglycaspis (7 spp. on Syzygium and Tristaniopsis) (Burckhardt 1991) and Ctenarytaina (4 spp. presumed to be associated with Syzygium) . As their hosts, these psyllids represent Australian biogeographical elements.
The Spondyliaspidinae is a species-rich subfamily of 23 recognised genera ) mostly restricted to the Australian biogeographical realm and associated with hosts in the Myrtaceae (Burckhardt 1991). Boreioglycaspis and Ctenarytaina are exceptional in that they occur also outside the Australian region. Ctenarytaina comprises 29 described species originating from tropical Asia (12 spp.), Australia (9 spp.), Oceania (6 spp.) and Africa (2 spp.) . Two Australian species, C. eucalypti (Ferris & Klyver) and C. spatulata Taylor, are economically important invasive pests in eucalypt plantations in Africa, Europe and the Americas were they are adventive (Queiroz et al. 2012;Makunde et al. 2020). Host plants are mostly Myrtaceae, but one species each develops on Boronia (Rutaceae), Eurya (Theaceae) and Fuchsia (Onagraceae), respectively.
Apart from the four species allegedly associated with Syzygium , two undescribed Ctenarytaina species were collected on Gunung Kinabalu that are described in the present paper. The taxonomy of Ctenarytaina daleae Burckhardt is revised and its host relationships are discussed.

Taxonomy
Diagnosis. Genal processes 0.3 times as long as vertex along mid-line, irregularly rounded anteriorly. Forewing oblong oval, widest in the middle, 2.3-2.7 times as long as broad, broadly rounded apically; vein C+Sc mostly straight, weakly concave in proximal third, cell c+sc narrow. Surface spinules present in all cells, forming cellular pattern; in cell r 2 above bifurcation of vein M, the cells are irregularly hexagonal consisting of two indistinct rows of spinules. No extra pore fields developed on abdominal intersegmental membrane. Basal segment of proctiger weakly curved posteriorly, hind margin with a row of stout setae; apical segment 0.2-0.3 times as long as basal segment. Paramere digitiform. Distal segment of aedeagus cuneate. Female terminalia strongly narrowed medially, bearing each an apical process on proctiger and subgenital plate, female proctiger dorsally serrate.
Redescription. Adult. Colouration. Head and thorax light reddish brown. Vertex with dark brown dot in the middle of either half; genal processes dark brown at base, yellow apically. Antenna light orange brown at base, getting gradually darker from segment 6 to apex which is dark brown or black. Pronotum with each two submedian dark dots and mesopraescutum with each one submedian dark dot along fore margin on either side. Legs yellow; profemora light greyish brown. Forewings light ochreous or amber-coloured, slightly lighter along fore margin; veins concolourous with membrane. Abdomen yellow or orange; base of female proctiger light brown. Younger specimens with less extended dark colour.
Structure. Conforming to the generic description of Burckhardt et al. (2020). Body length ♂ 1.4-1.5 mm, ♀ 1.5-1.9 mm (6 ♂, 6 ♀). Head deflexed 45° from longitudinal axis of body. Vertex rhomboidal, weakly concave at base; preocular sclerite forming flat tubercule; genal processes 0.3 times as long as vertex along mid-line, irregularly rounded anteriorly, contiguous medially; eyes weakly 'stalked' (Fig. 1). Antenna 0.6-1.0 times as long as head width. Metatibia 0.5-0.7 times as long as head width, weakly widening to apex, with 5 irregularly spaced apical spurs. Forewing ( Fig. 4) oblong oval, widest in the middle, 2.3-3.0 times as long as head width, 2.3-2.7 times as long as broad, broadly rounded apically; pterostigma, at base narrower than adjacent part of cell r 1 , regularly narrowing to apex, ending at apical fifth of wing; vein C+Sc mostly straight, weakly concave in proximal third, cell c+sc narrow; vein Rs almost straight, vein M long, with short, weakly diverging branches, vein Cu 1a relatively straight, reaching the wing margin distinctly distal to bifurcation of vein M. Surface spinules present in all cells, forming cellular pattern; in cell r 2 above bifurcation of vein M, the cells are irregularly hexagonal consisting of two indistinct rows of spinules (Fig. 5). No extra pore fields developed on abdominal intersegmental membrane. Male terminalia as in Figs 10-12. Proctiger 0.4-0.6 times as long as head width; basal segment, in profile, weakly curved posteriorly, irregularly beset with fine setae, hind margin with a row of stout setae; apical segment tubular, 0.2-0.3 times as long as basal segment. Subgenital plate, in profile, triangular, with almost straight dorsal margin; sparsely beset with short setae. Paramere, in profile, digitiform, almost straight anteriorly, wavy posteriorly, broadly rounded apically; inner face densely coverd in moderately long bristles. Distal portion of aedeagus slender in basal half, widening towards apex which is rounded; sclerotised end tube of ductus ejaculatorius small, weakly curved. Female terminalia as in Fig. 13. Proctiger 0.8-1.0 times as long as head width, 2.3-3.7 times as long as circumanal ring, cuneate; strongly narrowed medially, bearing an apical process, apical third serrate dorsally, subacute apically; sparsely beset with short setae, with a longitudinal lateral row of slightly longer setae in apical third and 2 longitudinal rows of peg setae near ventral margin in apical half. Subgenital plate 0.7-0.8 times as long as proctiger, in profile, bearing narrow, apically pointed process. Valvulae dorsalis and ventralis straight (Fig. 14); valvula lateralis pointed apically.
Host plant, biology and habitat. Adults were collected in large numbers on Leptospermum javanicum Blume (= L. flavescens auct.) and L. recurvum Hook.f. (Myrtaceae) suggesting that these two species constitute hosts. Leptospermum javanicum is widely distributed from Burma and southern Thailand to the Philippines, Malucu and Lesser Sunda Islands, and L. recurvum, is endemic to Gunung Kinabalu (Thompson 1989). It has been suggested that L. recurvum has split from the former after the last Pleistocene glaciation (Lee and Lowry 1980). The species occurs as a tree and at high altitudes as prostrate shrub on an outcrop of ultra basic rocks. It is one of the main shrub species of the summit zone above 3200 m altitude (Cockburn 1978;Corner 1978). A singe male was collected also on Syzygium korthalsianum (Miq.) Miq. (Myrtaceae), which is an unlikely host contrary to the statement by Burckhardt et al. (2020).
Comments. Ctenarytaina daleae is most similar to C. insularis Martoni & Armstrong in the posteriorly weakly lobed male proctiger, the digitiform paramere, the female terminalia, which are strongly narrowed medially and bear each an apical process on the proctiger and subgenital plate as well as the dorsally serrate female proctiger. It differs from the latter in the surface spinules forming rings consisting of two rows of spinules, the distal aedeagal segment which is evenly widening to apex rather than with a slender stalk and inflated apical part, the dorsally less concave female proctiger and the host plant: Leptospermum versus Syzygium.
Ctenarytaina daleae was described based on the male holotype and two female paratypes . The examination of a long series of material from the summit region of Gunung Kinabalu collected on Leptospermum spp. shows that the holotype of C. daleae corresponds to the species from Leptospermum but not the females which belong to C. smetanai sp. nov. described below. Ctenarytaina daleae and C. smetanai sp. nov. are similar in the head and forewing structure (Figs 1, 3, 4, 8) but differ in the male and female terminalia (18)(19)(20)23,24). Diagnosis. Genal processes 0.3 times as long as vertex along mid-line, irregularly rounded anteriorly. Forewing oblong oval, widest in the middle, 2.3-2.5 times as long as broad, narrowly rounded apically; vein C+Sc mostly straight, cell c+sc narrow. Surface spinules present in all cells, forming cellular pattern; in cell r 2 above bifurcation of vein M, the cells are irregularly hexagonal consisting of one or two indistinct rows of spinules. Extra pore fields developed on abdominal intersegmental membrane. Basal segment of proctiger weakly curved posteriorly, hind margin with a row of stout setae; apical segment 0.2 times as long as basal segment. Paramere weakly cuneate; inner face densely beset with long bristles. Distal portion of aedeagus slender in basal half, weakly inflated in apical half. Female terminalia cuneate; proctiger blade-shaped distal to circumanal ring, smooth dorsally, blunt apically.
Description. Adult. Colouration. Head and thorax light reddish brown. Vertex with dark brown dot in the middle of either half; genal processes dark brown at base, yellow apically. Antenna light orange brown at base, getting gradually darker from segment 6 to apex which is dark brown or black. Pronotum with each two submedian dark dots and mesopraescutum with each one submedian dark dot along fore margin on either side. Legs yellow; profemora light greyish brown. Forewings light ochreous or amber-coloured, slightly lighter along fore margin; veins concolourous with membrane. Abdomen yellow or orange; base of female proctiger light brown. Younger specimens with less extended dark colour.
Structure. Conforming to the generic description of Burckhardt et al. (2020). Body length ♂ 2.0 mm, ♀ 2.4 mm (1 ♂, 1 ♀). Head deflexed 45° from longitudinal axis of body. Vertex rhomboidal, weakly concave at base; preocular sclerite forming small tubercule; genal processes 0.3 times as long as vertex along mid-line, irregularly rounded anteriorly, contiguous medially; eyes weakly 'stalked' (Fig. 2). Antenna 0.8 times as long as head width. Metatibia 0.5-0.6 times as long as head width, weakly widening to apex, with 5 irregularly spaced apical spurs. Forewing ( Fig. 6) oblong oval, widest in the middle, 2.3-2.5 times as long as head width, 2.5-2.6 times as long as broad, narrowly rounded apically; pterostigma, at base wider than adjacent part of cell r 1 , regularly narrowing to apex, ending at apical quarter of wing; vein C+Sc mostly straight, cell c+sc narrow; vein Rs almost straight, vein M long, with short, weakly diverging branches, vein Cu 1a relatively straight, reaching the wing margin at bifurcation of vein M. Surface spinules present in all cells, forming cellular pattern; in cell r 2 above bifurcation of vein M, the cells are irregularly hexagonal consisting of one or two rows of surface spinules (Fig. 7). Extra pore fields present on abdominal intersegmental membrane. Male terminalia as in Figs 15-17. Proctiger 0.5 times as long as head width; basal segment, in profile, weakly curved posteriorly; irregularly beset with fine setae, bearing a row of short bristles along hind margin; apical segment tubular, 0.2 times as long as basal segment. Subgenital plate, in profile, triangular, slightly elongate, with weakly concave dorsal margin; sparsely beset with short setae. Paramere, in profile, weakly cuneate, relatively straight, narrowly rounded apically; inner face densely beset with long bristles. Distal portion of aedeagus slender in basal half, weakly inflated in apical half; sclerotised end tube of ductus ejaculatorius small, almost straight. Female ter- minalia as in Fig. 21. Proctiger 1.0 times as long as head width, 2.7-2.8 times as long as circumanal ring, cuneate; dorsal margin of proctiger concave, blade-shaped distal to circumanal ring, smooth dorsally, blunt apically; sparsely beset with short setae, with a longitudinal lateral row of slightly longer setae in apical half and 3 longitudinal rows of peg setae near ventral margin in apical half. Subgenital plate 0.7-0.8 times as long as proctiger, in profile, forming narrow process in apical half, pointed apically. Valvulae dorsalis and ventralis weakly curved (Fig. 22); valvula lateralis narrowly rounded apically.
Fifth instar immature unknown. Etymology. Named after C. Lienhard, Genève, eminent specialist of Psocodea and collector of most of the type series.
Host plant, biology and habitat. Unknown; a single female was collected on Tristaniopsis (Myrtaceae).
Comments. Ctenarytaina lienhardi sp. nov. shares with C. daleae, C. insularis and C. taylori the narrow forewings and the posteriorly weakly curved male proctiger. It differs from the two former species in the blade-shaped, dorsally smooth female proctiger and from the latter in the lack of a dark brown basal patch on the forewing.
Diagnosis. Genal processes 0.5 times as long as vertex along mid-line, irregularly rounded anteriorly. Forewing oblong oval, widest in the middle, 1.9-2.8 times as long as broad, narrowly rounded apically; vein C+Sc mostly straight, weakly concave in proximal third, cell c+sc narrow. Surface spinules present in all cells, forming cellular pattern; in cell r 2 above bifurcation of vein M, the cells are irregularly hexagonal consisting of one row of spinules. No extra pore fields developed on abdominal intersegmental membrane. Basal segment trapezoidal, hind margin with subapical angle bearing 5 short peg setae; apical segment 0.2-0.3 times as long as basal segment. Paramere very long and slender. Distal portion of aedeagus slender, weakly inflated apically. Female terminalia cuneate; dorsal margin of proctiger angularly concave at caudal end of circumanal ring, from there to pointed apex weakly convex, smooth.
Description. Adult. Colouration. Head and thorax dark reddish brown to almost black. Genal processes lighter than vertex, ochreous to brown. Antennal segments 1 and 2 light brown, segments 3-5 and basal third of segment 6 yellow to ochreous, apical two thirds of segment 6 and segments 7-10 dark brown to almost black. Mesoscutum with a broader median and two narrower submedian reddish brown longitudinal stripes. Fore and mid legs brown, tarsi and hind legs, including metacoxae, dirty yellowish. Forewings amber-coloured or light brown; veins concolourous with membrane. Hindwings whitish. Abdomen reddish brown to almost black dorsally, black ventrally; male and female terminalia light brown.
Structure. Conforming to the generic description of Burckhardt et al. (2020). Body length ♂ 1.9 mm, ♀ 2.0-2.2 mm (1 ♂, 2 ♀). Head deflexed 45° from longitudinal axis of body. Vertex rhomboidal, concave at base; preocular sclerite forming small tubercule; genal processes 0.5 times as long as vertex along mid-line, irregularly rounded anteriorly, well separated medially; eyes moderately 'stalked' (Fig. 3). Antenna 0.9-1.1 times as long as head width. Metatibia 0.5 times as long as head width, weakly widening to apex, with 5 irregularly spaced apical spurs. Forewing (Fig. 8) oblong oval, widest in the middle, 2.3-2.4 times as long as head width, 1.9-2.8 times as long as broad, narrowly rounded apically; pterostigma, at base narrower than adjacent part of cell r 1 , regularly narrowing to apex, ending at apical third of wing; vein C+Sc mostly straight, weakly concave in proximal third, cell c+sc narrow; vein Rs almost straight, vein M long, with short, weakly diverging branches, vein Cu 1a relatively straight, reaching the wing margin distinctly distal to bifurcation of vein M. Surface spinules present in all cells, forming cellular pattern; in cell r 2 above bifurcation of vein M, the cells are irregularly hexagonal consisting of one row of spinules (Fig. 9). No extra pore fields developed on abdominal intersegmental membrane. Male terminalia as in Figs 18-20. Proctiger 0.7 times as long as head width; basal segment, in profile, trapezoidal; irregularly beset with setae along anterior and posterior margins, hind margin with subapical angle bearing 5 short peg setae; apical segment tubular, 0.3 times as long as basal segment. Subgenital plate, in profile, elongate, with wavy dorsal margin; sparsely beset with short setae. Paramere, in profile, very long and slender, slightly narrowed in apical third, narrowly rounded apically; inner face with moderately long bristles in apical third and with two rows of bristles in basal two thirds. Distal portion of aedeagus slender, weakly inflated apically; sclerotised end tube of ductus ejaculatorius small, relatively straight. Female terminalia as in Fig. 23. Proctiger 1.1 times as long as head width, 2.9 times as long as circumanal ring, cuneate; dorsal margin of proctiger angularly concave at caudal end of circumanal ring, from there to pointed apex weakly convex, smooth; weakly beset with short setae, with a longitudinal lateral row of long setae in apical third and 2-3 longitudinal rows of peg setae near ventral margin in apical half. Subgenital plate 0.7 times as long as proctiger, in profile, evenly narrowing to pointed apex. Valvulae dorsalis and ventralis curved (Fig. 24).
Fifth instar immature unknown. Etymology. Named after the late A. Smetana, Ottawa, eminent staphylinid specialist and collector of the holotype.
Host plant, biology and habitat. One female was swept from Syzygium punctilimbum (Merr.) Merr. & L.M.Perry (Myrtaceae), a possible host, in moss forest. One male and one female were collected in an interception trap and one female was taken by sweeping vegetation.
Comments. Ctenarytaina smetanai sp. nov. differs from other congeners in the basal segment of the male proctiger which is trapezoidal and bears 5 short peg setae on the subapical angle of hind margin (Fig. 18).

Discussion and conclusions
Within the subfamily Spondyliaspidinae, which is almost entirely restricted to Australia, Ctenarytaina is exceptional in that it occurs also in Asia, Africa and Oceania. In fact, more than a third of the known species are native to Asia and only slightly less than a third is Australian. Among the 12 species known from Asia, the following four are apparently endemic to Gunung Kinabalu: Ctenarytaina baliota Burckhardt (on Syzygium punctilimbum), C. daleae (on Leptospermum javanicum and L. recurvum), C. loebli Burckhardt (on Syzygium sp.) and C. taylori Burckhardt (on Syzygium sp.). Here another two species are added, viz. C. lienhardi sp. nov. and C. taylori smetanai sp. nov. (both without host records), reflecting the species richness of the fauna of Gunung Kinabalu. All six Ctenarytaina species from this mountain appear to be endemic, a feature that is relatively rare in psyllids (Burckhardt and Queiroz 2021).