A new subspecies of Thaumantis hainana (Crowley, 1900) from Guizhou province, southwest region of China (Lepidoptera: Nymphalidae)

In this paper, the Thaumantis diores Doubleday, 1845-complex, including T. diores Doubleday, 1845 and T. hainana (Crowley, 1900), is studied, and a new subspecies, T. hainana libodiores Lang & Wang, ssp. nov., is described from Guizhou province, S.W. China.


Introduction
The genus Thaumantis Hübner, [1826] (Morphinae: Amathusiini) is a small Oriental genus and inhabits the tropical rainforests. Nandogea hainana Crowley, 1900 was described from Hainan Island, southwest of China as a distinct species (Crowley, 1900). Stichel (1906, in Wytsman) sunk it to an insular subspecies of Thaumantis diores Doubleday, 1845, viz. T. diores hainana (Crowley), and for a long time, it was considered as an endemic subspecies of Hainan (Fruhstorfer, 1911 in Seitz;Stichel, 1933 in Strand;D'Abrera, 1985;Gu & Chen, 1997). Osada et al. (1999) treated specimen from North of Laos as T. diores hainana (Crowley), but according to Inayoshi & Saito (2021), it is still T. diores diores Dbld. Basing upon differences of male genitalia, Lang (2010) recovered the species status of Thaumantis hainana (Crowley), and meanwhile, he found that this species also distributes in Asian mainland (Mt. Dayaoshan, Guangxi province, China). Inayoshi & Saito (2021) Inayoshi (pers. comm.), some populations of subspecies diores Dbld. from Vietnam also have hainana-like structure of male genitalia, and obviously, they are more closely related to continental Thaumantis hainana (Crowley) from Guangxi. Here, we propose Thaumantis diores Dbld. species complex which includes both T. diores Dbld. and T. hainana (Crowley). In Indo-Chinese region and south of China, the T. diores Dbld.-complex is possibly undergoing a process of speciation, therefore, its different species, whose male genitalia already are distinct, have their superficial appearances very similar from each other. This phenomenon can be also found in other Amathusiini species complex, such as the Faunis aerope (Leech, 1890)-complex and the Aemona amathusia (Hewitson, 1867)-complex from the same region (Indochina and South of China) (Monastyrskii, 2005;Nakamura et al. 2010;Lang, 2012;Monastyrskii & Lang, 2016;Nakamura, 2021;Huang, 2021). In this study, a special local population is found from Maolan, Libo, south of Guizhou, near the border with Guangxi. This locality is on the northern boundary of the range of the Thaumantis diores Dbld.-complex. It is quite different from the known mainland T. hainana hainana (Crowley) from Mt. Dayaoshan, Guangxi, and should be a new subspecies of T. hainana (Crowley). It seems that marginal effect is workable in the speciation process of this species complex.

Terminology
Terminology of male genitalia follows that of Klots (in Tuxen, 1970), excepting two specialized characters of the Thaumantis diores Dbld.-complex. Tegumen caudal end has a short and acute projection for which the term "uncus anticus" is used (Kirchberg, 1942); a short projection is present and attaches to the base of the dorsal ridge of the uncus, and Kirchberg (1942) used the term "crista" for this projection.

Taxonomy
Thaumantis hainana libodiores Lang & Wang, ssp. nov. (Figures 1-3 Diagnosis: The new subspecies can be distinguished from the nominate subspecies by the combination of the following characters: 1. It is obviously larger than insular individuals of the nominate subspecies; 2. Iridescent blue patch on forewing upperside is narrowing towards the costa, whereas its anterior margin is wide in the nominate subspecies; 3. The dorsal surface of tegumen has 2 or 3 deep grooves, whereas it is smooth in the nominate subspecies; 4. Uncus anticus is coniformshaped as in the nominate subspecies, but is more robust; 5. Crista is built as a finger like projection as in the nominate subspecies, but is obviously smaller.
The new subspecies is also superficially similar to Thaumantis diores diores Dbld., and it can be distinguished from the latter by the combination of the following characters: 1. Iridescent blue patches on upperside of both wings are often more restricted than those in T. diores diores Dbld.; 2. Iridescent blue patch on forewing upperside is narrowing towards the costa, whereas its anterior margin is wide in T. diores diores Dbld.; 3. Uncus anticus is coniform-shaped, whereas it is usually slightly flat in T. diores diores Dbld.; 4. Crista is built as a finger like projection, whereas it is very slender and flat in T. diores diores Dbld.
Notes: This subspecies also has features similar to Thaumantis diores Dbld., for example, its tegumen with grooves dorsally. Basing upon more characters shared with T. hainana (Crowley), we treat it as a subspecies of the latter: 1. Iridescent blue patches are often more reduced; 2. Uncus anticus is coniform-shaped; 3. Crista is built as a finger like projection.
Etymology: The specific name libodiores is composed by Libo, the type locality, and diores, the oldest name of this species complex.

Discussions
The fauna of Guangxi Province (China) is heterogeneous and diverse, and different mountain ridges are often isolated from each other here. Maolan Natural Reserve in Libo, Guizhou, type locality of Thaumantis hainana libodiores Lang & Wang, ssp. nov., is on the Guizhou-Guangxi border, and it is located at the southeastern fringe of the Yunnan-Guizhou plateau. Maolan is about 260 km to the northwest of Mt. Dayaoshan, which is an isolate ridge in east of Guangxi and a known habitat of T. hainana hainana (Crowley) in mainland. For Amathusiini, often local and slow flyers, such a distance and a degree of isolation can cause their speciation.
Only a male Thaumantis hainana hainana (Crowley) from Mt. Dayaoshan, Guangxi is examined in this study. Its male genitalia can hardly separate it from its conspecific relatives from Hainan Island, but it is obviously larger than those Hainanese individuals. Both its internal and external features are close to specimens of T. diores diores Dbld. from Vietnam (Inayoshi, pers. comm.). Therefore, populations of the T. diores Dbld.-complex from Guangxi and Vietnam might be a distinct subspecies of T. hainana (Crowley). Moreover, considering male genitalia differences, T. hainana libodiores Lang & Wang, ssp. nov. is also likely to be a distinct species. However, on the other hand, there is also another possibility that the T. diores Dbld.-complex is only a single species itself, T. diores Dbld., and all its taxa are conspecific and biogeographical subspecies, which are undergoing their vicariance (for example, differentiation of male genitalia structure). Of course, the above-mentioned hypotheses need more studies in the future.