The Trichadenotecnum corniculum species group from Thailand (Psocodea: Psocidae) El grupo de especies de Trichadenotecnum corniculum de Tailandia (Psocodea: Psocidae)

Five new species of the corniculum species group of the psocid genus Trichadenotecnum Enderlein, T. alfonsoi, T. lingens, T. palmula, T. afinifelix and T. separatum were described from Thailand. These species share a couple of male genital apomorphies with the other Oriental species of this species group recorded from China, Hong Kong, Malaysia, Singapore and Indonesia. The Japanese species of the corniculum group are considered to form a different clade placed as the sister to the rest of Oriental species.


Artículo
The corniculum species group of the psocid genus Trichadenotecnum was irst proposed by Yoshizawa (2003) for two Japanese species characterized by two male genital autapomorphies: the conical process on the paraproctal trichobothrial ield (trichobothrial process) and the denticulate or serrated hypandrial right corner. Subsequently, several species from China, Hong Kong, Malaysia, Singapore and Indonesia were assigned to this group (Yoshizawa & Lienhard 2004;Yoshizawa et al. 2014). The monophyly of this group and its deep divergence within the genus Trichadenotecnum were suggested by morphological data (Yoshizawa 2003), and later conirmed by extensive molecular phylogenetic analyses (Yoshizawa et al. 2016(Yoshizawa et al. , 2017. Through the TIGER project (Thailand Inventory Group for Entomological Research: http://sharkeylab.org/tiger [accessed on Feb 25, 2020]), many psocids (Psocodea: 'Psocoptera'), including about 50 species of the genus Trichadenotecnum, were collected and entrusted to the Geneva Natural History Museum. Of them, the alinguum and the marginatum species groups have already been studied (Yoshizawa & Lienhard 2015a, b). For this paper, we studied the corniculum species group from the TIGER material.

MATERIALS AND METHODS
All specimens examined in this study were collected through the TIGER project with Malaise traps; T-numbers are TIGER project sample numbers. The specimens were preserved in 80% ethanol. Type material will be deposited in the Queen Sirikit Botanical Gardens, Thailand.
As discussed below, all species described in this paper are supericially very similar to each other. Based on mor-phology, male-female association for separately collected specimens could not be established, and there were no samples in which possibly conspeciic males and females were collected simultaneously. Therefore, the following descriptions are exclusively based on male specimens.
Abbreviations used in the descriptions: BL = body length; FW = forewing length; HW = hindwing length; IO/D = shortest distance between compound eyes divided by longitudinal diameter of compound eye in dorsal view of head.

The corniculum group
See Yoshizawa (2003) and Yoshizawa & Lienhard (2004) for group diagnosis. In addition to the diagnostic characters mentioned by these authors, the following male genital features are present in all species examined here: paraproct with dorsal swelling at base of distal lobe; hypandrial median tongue well developed and thin; hypandrial right lateral corner densely covered by denticles; phallosome bifurcated apically. Thorax. Blackish brown except for white membranous region and white longitudinal line in middle of mesoscutum; metascutum with small white spot on posterior end of each scutum lobe.
Female. Unknown. Etymology. The species epithet honors our friend and colleague, Alfonso Neri García Aldrete, for his eminent contributions to the study of psocopterans.
Remarks. This species resembles T. pycnacanthum (Li, 2002) by the epiproctal and hypandrial structures but can be distinguished from it by the smaller body size, lack of the trichobothrial process, and by the apical shape of the phallosome.  3A) with tubercular trichobothrial process covered with denticles; with weak dorsal swelling at base of distal lobe; distal process slender. Hypandrium ( Fig. 3C) with well-developed left process; median tongue elongated, apically broadened, posterointernal margin serrated; right corner with posterolateral projection. Phallosome (Fig. 3D) with broad and medially concave distal process, its posterolateral corners denticulate.
Female. Unknown. Etymology. Named after the strongly extended hypandrial median tongue; lingens means licking in Latin (present participle of the verb lingere = to lick).
Remarks. This species can be distinguished from all other species of the corniculum group by its unique, strongly extended hypandrial median tongue. Thorax. Blackish brown except for white membranous region and white longitudinal line in middle of mesoscutum; metascutum with small white spot on posterior end of each scutum lobe.
Remarks. The elongated and parallel-sided hypandrial median tongue is unique to this species within the corniculum group. Thorax. Mostly blackish brown, mesoscutum with white longitudinal line in middle; metanotum pale in ground color, each scutum lobe with large brown marking; membranous region white.

Female. Unknown.
Etymology. This species is very similar to T. felix Thornton, 1961 (afinis means "related to" in Latin).
Remarks. This species resembles T. felix Thornton, 1961 in male genital structures but can be distinguished from the latter by the apical structure of the phallosome. Legs. Missing, except for dark brown coxae. Forewing. As in Fig. 1E. Terminalia. Epiproct (Fig. 6AB) lat, well expanded anteriorly, with weak swelling posteromedially. Paraproct ( Fig. 6A) with small and acutely pointed trichobothrial process; trichobothria broadly separated into two groups; distal lobe with broad dorsal swelling basally; distal process slender. Hypandrium (Fig. 6C) with laterally expanded keel near distal end of left corner, its posterior margin serrated; with pair of processes left to base of median tongue, left one short and broad, slightly bilobed, with rugose surface, right one well-developed, reaching to middle of median tongue; median tongue broad, distally rounded, with weakly serrated posterointernal margin; right corner not strongly developed, about same height of left corner. Phallosome (Fig.  6D) with pair of apically bifurcated processes, dorsointernal part of each process denticulate.
Female. Unknown. Etymology. Named after the widely separated paraproctal trichobothria; separatus means separated in Latin.
Remarks. This species is similar to T. pycnacanthum (Li, 2002) in some aspects of the hypandrial structures but is distinguished from it by the shape of the epiproct and the broadly separated paraproctal trichobothrial ields.

DISCUSSION
All ive species treated here are supericially very similar ( Fig. 1) but show signiicant differences in male genital structures (Figs 2-6). Except for T. alfonsoi n.sp. their descriptions are based on a single male specimen. However, judging from the intraspeciic variations observed in T. alfonsoi n. sp. or in the previously known species of the corniculum group (Yoshizawa 2003;Yoshizawa et al. 2014), the variations observed between the males examined for this study far exceed the known intraspeciic variability. Thus, describing new species based on a single specimen clearly appears justiied.
To date, species of the corniculum group are recorded from the Oriental (China including Hong Kong, Malaysia, Singapore and Indonesia) and the eastern Palaearctic (Japan) regions. All species described here from Thailand share two morphological characters with the previously known Oriental species: thin lamellate hypandrial median tongue and apically bifurcated phallosome. Both characters are apparently apomorphic, because they are not observed in the sister group of the corniculum group, the longimucronatum species group, and are also very rarely observed in other species of the genus Trichadenotecnum. Based on these synapomorphies, the Oriental species of the corniculum group likely form a monophyletic group representing the sister group of the clade composed of the two Japanese species. The latter also share a unique apomorphic character: the trichobothrial process arises from the distal end of the trichobothrial ield (Yoshizawa, 2003).
Within the Oriental clade, one monophyletic group composed of T. palmula n. sp., T. afinifelix n. sp., T. separatum n. sp., T. felix Thornton, 1961(Hong Kong), T. imrum New and Thoronton, 1976(Malaysia and Singapore), and T. cinnamonum Endang and New, 2014 can be recognized, which is characterized by the presence of one or two tubercular processes left to the hypandrial median tongue, both apparently representing an apomorphic condition (never observed in other Trichadenotecnum). T. pycnacanthum (Li, 2002) (China) may also belong to this clade because this species shares two apomorphies with T. separatum n. sp.: presence of a keel on the hypandrial left corner and apically forked phallosomal processes. However, the hypandrial tubercular processes are not illustrated for T. pycnacanthum (Li, 2002). Some of the hypandrial structures of T. pycnacanthum are not clearly illustrated in the original description so that the examination of the type material of this species is needed to decide its phylogenetic placement. Among the species from Thailand, T. alfonsoi n. sp. and T. lingens n. sp. are characterized by the presence of a well-developed hypandrial left process. However, the hypandrial left process is widely observed throughout Trichadenotecnum, and a less developed left process can also be seen in T. palmula n. sp. and T. imrum, both belonging to the clade with the tubercular hypandrial processes.
The TIGER material contains ive species of the corniculum group, which far exceeds the previously known diversity of this group in other countries or regions: two species from Japan, two from China including Hong Kong, and two from Malaysia + Singapore + Indonesia. This strongly suggests that the diversity of the corniculum group is in reality much higher, especially in the Oriental region. The present results show the eficiency of the sampling conducted by the TIGER project and the great importance of this project for uncovering insect diversity in Thailand.

ACKNOWLEDGMENTS
We dedicate this paper to our colleague and friend, Alfonso Neri García Aldrete, in recognition of his outstanding contribution to the systematics of Psocoptera. We thank Michael Sharkey for entrusting the psocids collected in the course of the TIGER project to the Geneva Natural History Museum, and we are grateful to Thérèse Cuche, former technician at the Geneva Museum, for her tireless sorting and labeling of this huge collection. This study was partly supported by JSPS grants 19H03278 and 24570093 to KY.