Two new species of the genus Teredorus Hancock, 1906 (Orthoptera, Tetrigidae) from China, with a key to the species of the genus

Abstract Taxonomy of a tetrigid genus Teredorus Hancock is reviewed. Two new species, Teredorus parvipulvillus sp. n. and Teredorus hunanensis sp. n. are described from China and an updated identification key to all known species of the genus is given, as well as brief comments on phylogenetic relationships, biology and ecology.

The genus Teredorus Hancock is considered as a member of the subfamily Tetriginae based on the following characters: the filiform antennae; width of frontal costa narrower than first segment of antenna; lateral lobes of pronotum turned downwards, posterior angles rounded; the first segment of posterior tarsi equal to or slightly longer than the third one.
The identification of the genus Teredorus is problematic due to the absence of an identification key at the species level, so the original descriptions of the genus Teredorus are brief and imprecise. In this paper, the clarification of the taxonomic status of the genus Teredorus is revised and the utility of the characters used to diagnose is determined. In addition, Teredorus parvipulvillus sp. n. and Teredorus hunanensis sp. n. are described from China and an updated key to the species of Teredorus is given, as well as brief comments on phylogenetic relationships, biology and ecology.

Material and methods
Specimens examined are deposited in the following institutions: Institute of Zoology, Shaanxi Normal University, Xi'an, China (IZSNU); School of Chemistry and Bioengineering, Hechi University, Yizhou, China (SCBHU).
Photographs were taken with an Olympus digital camera with a series of images montaged using the program CombineZ5.3 (Hadley 2006).
Morphological terminology and measurement landmarks method followed those of Zheng (2005) and Deng et al. (2007). Descriptions of the species are mostly based on female specimens because many Tetriginae males are usually difficult to discriminate and thus the identification is usually done by association with females collected at the same time and place. Measurements are given in millimetres (mm). The specimens measured correspond to the material designated as holotypes, allotypes and paratypes.

Taxonomy
Teredorus Hancock, 1906Teredorus Hancock 1906Hancock 1915: 109;Kirby 1910: 30;Bruner 1910: 118;Shishodia 1991: 70-71;Blackith 1992: 181;Liang and Zheng 1998: 130;Zheng 2005: 219;Zheng 2006: 21-22;Deng et al. 2007: 201-202 Female. Size small, slender. Length of body (from vertex to apex of hind process) 3.8 times as its width (between posterior angles of lateral lobes of pronotum), head distinctly exerted above upper level of pronotum (Fig. 1A). In dorsal view, vertex strongly contracted forward drawing the eyes very near together ( Fig. 2A, D), not exserted before eyes, midkeel distinct, extended to occiput; vertex not visible before eyes in lateral view, frontal ridge straight before lateral ocellus, arc-protruding between antennae, longitudinal furrow narrower than width of 1st segment of antennae. Antenna filiform, 15-segmented, inserted between lower margin of eyes (Fig. 2B), mid segments 4-7 times as long as wide. Eyes elevated above the pronotum (Fig. 2B), globular in shape, lateral ocelli placed on slightly lower than middle of anterior margins of eyes (Fig. 2C). Disc of pronotum smooth, with numerous small granules, mid keel of pronotum entire, upper margin of pronotum slightly undulating before shoulders and straight behind shoulders in profile (Fig. 1A). Anterior margin of pronotum straight, lateral keels of prozona short and parallel (Fig. 2D), humeral angle obtuse, without abbreviated carinae between shoulders. Posterior process of pronotum narrow, long cone-shaped, surpassing apex of hind femur and reaching apex of hind tibia (Fig. 1A, B). Lateral lobes of pronotum turned downwards, posterior angles rounded, posterior margin of each lateral lobe with two concavities. Visible part of tegmina ovate (Fig. 2E), apex narrowly rounded, with length 2.5 times its width. Hind wings developed, reaching and slightly surpassing apex of posterior process of pronotum (Fig. 1A). Upper and lower margins of fore femur and mid femur nearly straight (Fig. 2F, G), width of mid femur narrower than width of tegmina (1: 1.4) (Fig. 2E). Hind femur stubby (Fig. 2H), with length 3.3 times its width, mid keel of dorsal and ventral side of hindfemur dentate, antegenicular right angle and genicular denticles acute angle. Outer side of hind tibia with two to three spines, inner side without spine (Fig. 2I). Length of first segment of posterior tarsus longer than third, first pulvillus and third normal, equal in length, apex abtuse; second pulvillus degenerated and very small (Fig. 2J), apex acute. Ovipositor narrow and long, length of upper valvulae 4.2 times its width, upper and lower valvulae with slender saw-like teeth (Fig. 2K). Length of subgenital plate equal to width, middle of posterior margin of subgenital plate triangularly projecting (Fig. 2L).
Diagnosis. This species can be easily distinguished from other species of the genus by inner side of hind tibia without spine; second pulvillus of posterior tarsus degenerated, distinctly smaller than first and third. It is only similar to Teredorus ebenotus , from which it differs in: antenna inserted between lower margin of eyes; upper margin of pronotum slightly undulating before shoulders and straight behind shoulders in profile; posterior process of pronotum reaching apex of hind tibia; width of mid femur distinctly narrower than tegmina. Teredorus ebenotus  exhibits antenna inserted below lower margin of eyes; upper margin of pronotum straight in profile; posterior process of pronotum reaching middle of hind tibia; width of mid femur equal to tegmina.
Etymology. The new species' name is derived from Latin parv and pulvillus, meaning second pulvillus of posterior tarsus degenerated and very small.
Habitat. The new species lives in moist stony on the border of streams in tropical rainforests.

Teredorus hunanensis sp. n.
http://zoobank.org/564AAF62-3BB8-4324-BEF2-3D916E448019 Figs 3-4 Female. Size small, slender. Length of body (from vertex to apex of hind process) 3.2 times as its width (between posterior angles of lateral lobes of pronotum), head not exerted above upper level of pronotum (Fig. 4B). In dorsal view, vertex strongly contracted forward drawing the eyes very near together (Fig. 4D), not exserted before eyes, midkeel distinct, extended to occiput; vertex visible before eyes in lateral view, vertex and frontal ridge forming rounded, frontal ridge slight concave between lateral ocelli, arc-protruding between antennae, longitudinal furrow narrower than width of 1st segment of antennae. Antenna filiform, 15-segmented, inserted below lower margin of eyes (Fig. 4B, C), mid segments 5-6 times as long as wide. Eyes globose, lateral ocelli placed on slightly lower than middle of anterior margins of eyes (Fig. 4C). Disc of pronotum smooth, with numerous small granules, mid keel of pronotum entire (Fig. 3B), upper margin of pronotum slightly undulating before shoulders and straight behind shoulders in profile (Fig. 3A). Anterior margin of pronotum straight, lateral keels of prozona unconspicuous, parallel (Fig. 4D), humeral angle obtuse, without abbreviated carinae between shoulders. Posterior process of pronotum narrow, long cone-shaped, surpassing apex of hind femur and reaching one third of hind tibia ( Fig. 3A). Lateral lobes of pronotum turned downwards, posterior angles rounded, posterior margin of each lateral lobe with two concavities. Visible part of tegmina ovate (Fig. 4E), apex narrowly rounded, with length 2.8 times its width. Hind wings developed, reaching and slightly surpassing apex of posterior process of pronotum (Fig.  4A). Upper and lower margins of fore femur and mid femur straight (Fig. 4F, G), width of mid femur equal to tegmina. Hind femur stubby (Fig. 4H), with length 2.8 times its width, mid keel of dorsal and ventral side of hindfemur dentate, antegenicular right angle and genicular denticles acute angle. Outer side of hind tibia with five to six spines, inner side with four to six spines (Fig. 4I). First segment of posterior tarsus equal to third in length, three pulvilli equal in length, apices of all pulvilli abtuse (Fig. 4J). Ovipositor narrow and long, length of upper valvulae 3 times its width, upper and lower valvulae with slender saw-like teeth (Fig. 4K). Length of subgenital plate equal to width, middle of posterior margin of subgenital plate triangularly projecting (Fig. 4L).
Colouration. Body dark brown. Hind wings black. Fore and mid femora brown, with two black rings in the middle, first segment of tarsi black, apex of second segment black. Hind femora dark brown or brown, inner side black. Hind tibiae black, with two yellowish brown rings in the middle (Fig. 3A).
Diagnosis. This species is similar to Teredorus flavistrial , from which it differs in: frontal ridge slight concave between lateral ocelli in profile; posterior process of pronotum reaching one third of hind tibia; width of mid femur equal to tegmina; first segment of posterior tarsus equal to third in length, three pulvilli of first segment of posterior tarsus equal in length. Teredorus flavistrial , exhibits frontal ridge straight before lateral ocellus in profile; posterior process of pronotum reaching apex of hind tibia; width of mid femur narrower than width of tegmina; length of first segment of posterior tarsus longer than third segment, third pulvillus of first segment of hind tarsi longer than the first and second pulvilli.
Etymology. The new species was named after the type locality, Hunan, China.
Habitat. The new species lives in moist stony on the border of streams in rainforests. Distribution. China (Hunan).

Discussion
The original description of the genus Teredorus Hancock is based on characters from the external morphology exclusively. The morphology of Teredorus is quite homogeneous, and the species can be differentiated mostly by having vertex very strongly narrowed toward the front drawing the eyes together and in front forming a triangular shape. Recent molecular studies, based on Teredorus guangxiensis cytochrome c oxidase subunit I gene (Fang et al. 2010) showed Teredorus Hancock, 1906 (subfamily Tetriginae) to be closely related to the genus Systolederus Bolivar, 1887 (subfamily Metrodorinae) (Fig. 5), but Fang et al. did not further comment why these two genera are related in morphology. The external morphology of the species of Teredorus is very similar to that of the species of Systolederus, in spite of being included in different subfamilies, these two genera share vertex very strongly narrowed toward the front drawing the eyes together and in front forming a triangular shape. Teredorus is mainly characterized by having lateral lobes of pronotum turned downwards, posterior angles rounded, Systolederus exhibits lateral lobes of pronotum produced outwards, with truncate posterior angles. Externally, its segregation is based on the relative shape of posterior angles of lateral lobes of pronotum, which is a diagnostic character to effectively separate Metrodorinae from Tetriginae. Accordingly, Teredorus and Systolederus can combine to the same genus, but need to be further studied. The genus shows a striking disjunct distribution, with its type species known from Peru in South America and other members of the genus from China, India and Nepal in Asia. We infer that Teredorus may be widely distributed all over the world, but they have not been collected and studied at present in most of continents, e.g. Africa, Europe, American Continent, etc. According to the diagnosis of the Tetriginae (Zheng 2005), Teredorus parvipulvillus sp. n. and Teredorus hunanensis sp. n. clearly belong to this subfamily. We place two new species in Teredorus based on lateral lobes of pronotum turned downwards, posterior angles rounded. Additional characters support this placement, as pronotum generally not produced above head in front, antenna filiform, frontal costa moderately forked between antennae, not forming a frontal scutellum, its width narrower than the basic segment of antenna, usually separated by a sulcus.
Many species of the genus Teredorus are usually associated with, but not limited to, moist environments, living along the moist stony on the border of streams. Some have suggested that with the pronotum subcylindrical and smooth, the often flattened front and median limbs are used like paddles for swimming. Their diet consists mostly of algae growing on the moist stony surface, along with lichens and other forms of humus. They generally overwinter as adults. Teredorus are likely to disappear if environments become polluted or disturbed by human beings.