Tremex katayamai Shinohara & Kurihara 2023, n. sp.
Creators: name: Shinohara, Akihiko
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Siricidae
Tremex
Tremex katayamai

description: Tremex katayamai Shinohara & Kurihara, n. sp.
(Figs 1D, 2E, 3D, 5I, 6B, 7G, H, 10D, 11C, 15; Tables 1, 2, 4)
Description. Female (holotype: Figs 1D, 2E, 3D, 5I, 6B, 10D, 11C). Length without ovipositor about 29 mm. Head pale brown, ocellar area darkened. Mandible brown with apical part black. Antenna pale brown, with flagellomeres 2–6 darkened particularly on ventral/posterior surface. Pronotum pale brown, with ventral lateral surface, narrow ventral anterior margin and narrow posterior margin blackish brown to black. Cervical sclerite black, with pale brown marks on dorsal and ventral surfaces. Mesoscutum pale brown with large anterior lateral parts and narrow posterior margin black. Mesoscutellum, including parascutal lobe, pale brown. Mesepisternum black, with large elongate mark extending from anterior dorsal margin nearly to posterior margin. Mesepimeron black, with posterior 2/3 pale brown. Metanotum black with large pale brown areas. Metepisternum and metepimeron black. Fore leg pale brown, with anterior and lateral surface of coxa and base of trochanter black and apex of femur and base and anterior surface of tibia and tarsomere 1 tinted with creamy white. Mid leg black, with apex of trochanter, most of femur, tibia and tarsus pale brown; apex of femur and basal half of tibia tinted with creamy white. Hind leg black, with narrow apex of femur, basal 1/3 and all inner surface of tibia and all tarsus creamy white; outer surface of apical 2/3 of tibia and apical part of tibia slightly darkened. Wings brownish hyaline, with rather indistinct dark cloud in anterior half of forewing. Abdomen black, with following pale brown: lateral part (but not lateral margin) of tergum 1, most of tergum 2, spot near lateral margin and large paired transverse marks on tergum 6, most of terga 7 and 8 (except large anterolateral margins and narrow obscure mark in anterior part and along median line), tergum 9 (except broad anterior margin, narrow lateral posterior margin and large transverse mark in anterior part of precornal basin) and cornus (apex darkened); sterna 3–6 creamy white (except large lateral margins); ovipositor sheath blackish brown.
Antenna (Fig. 5I) with 15 antennomeres, flagellomere 6 about 0.82 times as long as wide. Pronotum (Fig. 3D) with MPL about 0.74 times as long as OOCL. Hind tibia about 1.05 times as long as hind tarsomere 1; dorsal margin of hind tibia straight or very shallowly concave (Fig. 6B). Forewing about 1.21 times as long as ovipositor sheath. Abdominal tergum 8 about 0.95 times as long as terga 5–7 combined; precornal basin short, its length about 0.61 times as long as wide, widest in anterior part (Figs 2E, 11C); ovipositor sheath about 2.2 times as long as apical sheath.
Male. Unknown.
Variation. The holotype is the largest and palest specimen. The seven specimens examined vary from 17 to 29 mm in length without ovipositor. The posterior margin of the pronotum is often broadly marked with black. The brownish marks on the mesoscutum, mesepisternum, abdominal tergum 1 and the precornal basin may become ob-solete or missing. The black mark on the abdominal tergum 8 may become larger but always limited in anterior part. The structural characters vary as follows: Antenna with 14 or 15 antennomeres. Pronotum with MPL 0.71–0.81 (av-erage 0.76) times as long as OOCL. Hind tibia 1.05–1.14 (average 1.11) times as long as hind tarsomere 1. Forewing 1.21–1.33 (average 1.28) times as long as ovipositor sheath. Abdominal tergum 8 0.95–1.00 (average 0.97) times as long as terga 5–7 combined; precornal basin short, its length 0.57–0.64 (average 0.6) times as long as wide, always widest in anterior part (Figs 2E, 11C); ovipositor sheath 2.20–2.45 (average 2.36) times as long as apical sheath.
Type material. Holotype: ♀, Japan, Honshu, Tochigi Pref., Utsunomiya-shi, Nagaoka-machi, Shimonagaoka, 26. VI. 2021, T. Kurihara (NSMT). Paratypes: 3♀, same data as for holotype (NSMT, TPM); 3♀, same data as for holotype, except for 21. VI. 2021 (NSMT, TPM).
Distribution (Fig. 15). Japan (Honshu).
Host plants. Sapindaceae: Acer pictum Thunb. subsp. dissectum (Wesm.) H.Ohashi f. dissectum (Wesm.) H.Ohashi. Betulaceae: Carpinus laxiflora (Siebold et Zucc.) Blume. Fagaceae: Quercus serrata Murray. The collector observed oviposition on the weakened trees of the above three plant species.
Etymology. This species is named after Dr. Eisuke Katayama, Ôtawara, who first realized the importance of the newly acquired material and kindly brought it to Shinohara’s attention.
Remarks. Tremex katayamai may look similar to T. fuscicornis, T. nakanei or T. contractus among the Japanese congeners but it will be separated from the latter three species by the characters given in the key.
Tremex katayamai runs to T. simulacrum Semenov-Tian-Shanskij, 1921, in Gussakovskij’s (1935) key to the Palaearctic species. In Maa’s (1949) key to the Old World species, T. katayamai goes to couplet 12. It agrees with the first line (T. temporalis) in the comparatively long pronotum (about 2/3 as long as the ocello-occipital line) but disagrees with it in the largely pale brown head and thorax. The new species agrees with the second line (T. simulacrum, T. jakovlevi and T. fuscicornis) in the largely pale brown head and thorax but disagrees with it in the comparatively long pronotum (not “at most about a-half as long as the ocello-occipital line”). Although Maa (1949) included T. simulacrum in his key, he suggested synonymy of this species with T. fuscicornis in the discussion.
On the other hand, T. katayamai runs to T. guangchenii Xiao & Wu, 1983, in the keys to the Chinese species by Xiao & Wu (1983) and Xiao et al. (1992), despite that these keys also include T. simulacrum. In the couplet 7 in the former key and the couplet 8 in the latter key, T. simulacrum (and T. gongliuensis and T. fuscicornis) is separated from T. guangchenii (and T. temporalis and T. abei) by the relative lengths of the pronotum; T. simulacrum has the median length of the pronotum (MPL) about 1/2 of the ocello-occipital distance (OOCL), whereas T. guangchenii has it about 2/3 of the OOL. The length of the pronotum in T. simulacrum was not mentioned in the original description (Semenov-Tian-Shanskij 1921), while Gussakovskij (1935), most probably after examining the type material, mentioned “pronotum, as in T. fuscicornis F., not elongated, much shorter in middle than vertex” (p. 72, original in Russian). I follow Xiao & Wu (1983) and Xiao et al. (1992) for the interpretation of T. simulacrum.
Tremex katayamai differs from T. simulacrum in having the antenna with 14 or 15 antennomeres, the pronotum with the MPL 0.71–0.81 (average 0.76) times as long as OOCL, the hind tibia largely black (whitish at least basally) (Fig. 6B) and the tergum 8 entirely pale brown except for a narrow transverse black mark near the anterior margin (Fig. 11C). Tremex simulacrum has only 13 antennomeres, the median length of the pronotum (MPL) about 1/2 of OOCL, the hind tibia yellowish and the apical half of the tergum 8 black (Semenov-Tian-Shanskij 1921; Gussakovskij 1935; Xiao & Wu 1983).
Tremex katayamai is different from T. guangchenii in the pale brown antenna (Fig. 5I) and ovipositor sheath (sometimes partly darkened), the entirely or mostly black abdominal tergum 3, and the ovipositor sheath 2.2– 2.45 (average 2.34) times as long as the apical sheath. Tremex guangchenii has the antennomeres 3–10 black, the abdominal tergum 3 reddish brown with the posterior margin black and the ovipositor sheath blackish brown and about 2.1 times as long as the apical sheath (Xiao & Wu 1983; Xiao et al. 1992).
description: Published as part of Shinohara, Akihiko, 2023, The woodwasp genus Tremex (Hymenoptera, Siricidae) of Japan, pp. 1-40 in Zootaxa 5239 (1) on pages 23-24, DOI: 10.11646/zootaxa.5239.1.1, http://zenodo.org/record/7621749