Tirachoidea siamensis, Hennemann & Conle, 2008

Hennemann, Frank H. & Conle, Oskar V., 2008, Revision of Oriental Phasmatodea: The tribe Pharnaciini Günther, 1953, including the description of the world's longest insect, and a survey of the family Phasmatidae Gray, 1835 with keys to the subfamilies and tribes (Phasmatodea: " Anareolatae ": Phasmatidae), Zootaxa 1906, pp. 1-316 : 244-249

Tirachoidea siamensis spec. nov.

( Figs. 139, 142, 161–162, 218–220, 273, 298, 324, 357, 364, 406, 415, 423)

HT, ♀: N. Thailand, Maetha , Lamphun, X.1998, Coll. Phimpisarn; BMNH (E) 2005-98 (BMNH).

PT, 2 ♂♂, 1 ♀: N. Thailand, Maetha , Lamphun, X.1998, Coll. Phimpisarn; BMNH (E) 2005-98 (BMNH).

PT, 1 ♂, 1 ♀: N. Thailand, Maetha , Lamphun, X.1998, Coll. Phimpisarn (coll. PDB) .

PT, ♂: Thailand, Lomgao , Petchabun, Phimpisarn, 21.X.1985; BMNH (E) 2005-98 (BMNH).

PT, 3 ♂♂: N-Thailand, Dansai Loei, leg. 14.–15.IX.1986 (coll. FH, No. 0142-1 to 3) .

PT, 2 ♀♀: N-Thailand, Chiang Mai, leg. Lehmann IV. 1994 (coll. FH, No’s 0142-4 & 7) .

PT, 6 ♀♀: Central Thailand, Lemgao, Petchabun, X. 1985 (coll. FH, No’s 0142-5 to 6 & 8 to 11) .

PT, 1 ♂, 1 ♀: ex Zucht: F. Hennemann I. 1997, urspr.: N-Thailand, Chiang Mai (coll. FH, No’s 0142-12 & 13) .

PT, 2 ♂♂, 60 eggs: ex Zucht F. Hennemann 1997, urspr.: N-Thailand, Chiang Mai (coll. FH, No’s 0142-14, 15 & ED) .

PT, 12 ♀♀: Thailand, Lemgao, Petchabun, leg. Lehmann (coll. OC, No’s 00136 to 146) .

PT, ♀: Thailand, Prov. Kon Kaen, Bez. Phu Wiang, Tam Phra , 250m, Dry Dipterocarpus Forest, 2.11.1984, H. Felten leg. ( SMFM) .

Further material: [6 ♀♀, 1 ♂]:

THAILAND:

1 ♀: Thailand , Chiang Mai, IV. 1994 (coll. OZ, No. 0245-1) ; 1 ♀: Thailand, Potvin vend. ( ISNB) ; 1 ♀, 1 ♂: Thailand, Lemgao, Petchabun , don N. Mal ( ISNB) . 1 ♀: ex Zucht F. Hennemann 1997, urspr.: N-Thailand, Chiang Mai (coll. FH, No 0142-15) .

VIETNAM:

1 ♀: Tonkin, Hoabinh, 8.1918, R.V. de Salvaza leg. ( BMNH) ; 1 ♀: Museum Paris, Cochinchina, Cap St. Jaques, com, Fuquet, 1913; Pharnacia westwoodi Wood-Mason L. Chopard & L. Berland det. ( MNHN) .

Diagnosis: Closely related to T. cantori ( Westwood, 1859) but differing by: the relatively longer mesothorax; more globose vertex; more distinct tubercles of the vertex and entirely brown antennae of both sexes. ♀♀ furthermore differ by: the slightly more slender body (maximum body width 12.0–14.0 mm); more shallow posteromedian excavation of the anal segment (Fig. 219); broader and rounded lateral lobes of abdominal tergite VII (Fig. 273); more distinct ridges of the praeopercular organ (Fig. 364) and orange or red armature of the legs. ♂♂ differ by the rounded apex of the semi-tergites of the anal segment (Fig. 220); longer meso- and metabasitarsi; more sparse armature of the legs and presence of a ± distinct, triangular median tooth on the posterodorsal carina of the meso- and metatibiae. Apart from these morphological features the geographical pattern of T. siamensis spec. nov. (Fig. 406) well separates it from T. cantori , which is distributed more southward and restricted to Peninsular Malaysia and very southern Myanmar (Mergui District).

Also similar to T. jianfenglingensis ( Bi, 1994) but easily distinguished by: the generally smaller size; more robust body and legs; less conical vertex; uniform colouration of the head and shorter basitarsi of both sexes. ♀♀ furthermore differ by: the considerably more prominent armature of the mid and hind legs (Fig. 324); basally elevated outer ventral carinae of the mesofemora; less distinct praeopercular organ (Fig. 364); more distinctly excavated posterior margin of the anal segment (Fig. 219) and dark brown meso- and metasternum. ♂♂ clearly differ from those of T. jianfenglingensis by: lacking the white diagonal line of the tegmina; less prominent and less numerous serrations of the anterodorsal carina of the profemora as well as the much more slender and elongate semi-tergites of the anal segment (Fig. 220). T. jianfenglingensis is generally distributed more north and eastward than T. siamensis spec. nov., being restricted to SW-China, Northern Vietnam and the very northern portions Thailand (Fig. 405).

The eggs readily differ from all other known eggs of the genus by the creamish grey colour and very defined black lateroventral marking of the capsule, slender micropylar plate and narrowed polar-area as well as the very large, conical capitulum (Figs. 161–162).

Etymology: The name refers to the distribution of this new species and is derived from Thailand’s old name “ Siam ”.

Description: The colouration is described from both dried and live specimens.

♀♀ (Fig. 142): Of medium size (body length 194.0–229.0 mm) and moderately robust for the genus (12.0–14.0 mm) with prominent leg armature. General colouration of body and legs varying from pale yellowish or greyish over mid to almost blackish brown, the body usually all over set with numerous paler and darker brown speckles. Occasionally the dorsal surface of the head and body may be furnished with several large but irregular pale yellowish markings. Cheeks with two faint and weakly defined longitudinal streeks in the lower portion. Meso- and metasternum dark brown with a few whitish spots roughly arranged in two longitudinal rows. Abdominal sternites with ± distinct whitish mottling. Legs with irregular often very indistinct whitish or pale grey transverse bands, which are more defined on the ventral surfaces. Complete armature of legs dark red with black points; Pre-median and apical dorsal lobes of the meso- and metatibiae blackish brown to black. Eyes dark reddish brown. Antennae reddish mid to dark brown.

Head (Fig. 298): About 1.5x longer than wide, vertex strongly rounded and set with a pair of ± distinct forward-pointing spiniform tubercles; the dextral one considerably larger than the sinistral. Between the bases of antennae with a deep oval impression. Eyes large, circular and strongly convex, the anterior margin slightly triangular; length contained a little more than 3x in that of cheek. Antennae reaching about 3/4 the way along mesonotum and consisting of about 30 antennomeres. Scapus dorsoventrally flattened, 2.3x longer than wide and very gently narrowed towards the base. Pedicellus a little more than 1/3 the length of scapus, indistinctly longer than wide and cylindrical. III slightly longer than pedicellus, IV strongly shortened, V–XV increasing in length. All finely bristled.

Thorax: Pronotum slightly narrower and shorter than head, almost 1.3 x longer than wide and conspicuously widened towards the posterior. Anterior margin raised, followed by a well defined transverse furrow and with a small rounded impression at the lateral angles. Median transverse depression rather distinct but short and covering less than half the width of segment. Mesothorax about 1.8x longer than head and pronotum combined, very slightly constricted at anterior margin and broadened at the posterior. Mesosternum with a blunt longitudinal carina along lateral margins. Metanotum distinctly shorter than mesonotum, about 1.2x longer than wide, rectangular and with a very minute spine posteromedially. Very minute, scale-like traces of tegmina and alae present (ca. 1.0 mm)

Abdomen: Median segment almost 4/5 the length of metanotum, slightly trapezoidal and with the anterior margin rounded. Segments II–VI increasing in length, II 1.2x, VI longest segment and about 2x longer than wide. Tergites II–VII with a transverse, scale-like tubercle which is most decided on V; sometimes lacking on II and III. VII about 2/3 the length of VI, posterolaterally dilated into a broad rounded lobe, which extends by about half the width of segment (Fig. 273). Praeopercular organ formed by two short, but rather acute converging carinae, which terminate in a minute spine posteriorly, near posterior margin of sternum VII (Fig. 364). Tergite VIII a little longer than VII and longer than IX and X combined , distinctly narrower than previous, slightly constricted medially and about 3x longer than wide. IX about half the length of previous, 1.3x longer than wide and strongly convex. Anal segment a little longer than IX, with a very indistinct median carina and a broad triangular excavation posteromedially; posterolateral angles roundly triangular (Fig. 219). Supraanal plate broad, rounded, with a fine median carina and a small posteromedian notch. Cerci small, oval in cross-section, gradually tapered towards a pointed tip and reaching apex of anal segment. Gonapophyses dull yellowish brown, elongate, up-curving and slightly projecting over anal segment. Subgenital plate strongly keeled, boat-shaped and projecting over apex of abdomen by about half the length of anal segment (Fig. 218).

Legs: All of moderate length and rather robust, the meso- and metafemora very gently down-curving and slightly swollen basally. Profemora as long as pro- and mesonotum combined, mesofemora slightly shorter than mesothorax, metafemora slightly projecting over posterior margin of abdominal segment IV and hind tarsi reaching about half way along tergite VIII. Anterodorsal carina of profemora armed with 10–14 pointed, triangular serrations. Posterodorsal carina set with 7–11 small triangular teeth. Posteroventral carina with 12– 14 pointed serrations. Anterodorsal carina of protibiae sparingly serrate, posterodorsal carina with 6–8 minute teeth, posteroventral sparingly serrate. All carinae of meso- and metafemora armed with strongly pointed spines and teeth of various sizes; these become more increasingly larger towards the base of femur and are in general more minute on the dorsal carinae. Two outer ventral carinae of mesofemora gently elevated subbasally, the posteroventral carina bearing 2–3 conspicuously enlarged and broadened lobe-like triangular teeth in that portion. Posterodorsal carina with a ± large, triangular sub-basal tooth and a slightly enlarged tooth apically (Fig. 324). Medioventral carina of meso- and metafemora armed with 5–7 prominent, hooked spines which increase in size towards base of femur; the 2 nd and 3 rd being largest. All carinae of meso- and metatibiae densely armed with pointed spines; more sparingly and minutely on dorsal carinae. Posterodorsal carina armed with a very prominent, foliaceous triangular lobe pre-medially and forming a conspicuous rounded and dentate lobe apically. Spines of the medioventral carina considerably longer and more slender than those of the two outer carinae. Probasitarsus with all carinae distinctly but uniformly elevated and unarmed; as long as remaining tarsomeres combined except claw. Meso- and metabasitarsi with a strongly raised and apically rounded dorsal carina, all carinae serrate; a little longer than following three tarsomeres combined.

♂♂ ( Fig. 139, 423): Of moderate size (body length 128.5–139.0 mm) with long alae (66.5–71.0 mm). General colouration of body and legs yellowish to greyish cream-brown, occasionally with a few small white spots on mesonotum. Cheeks sometimes with a very indistinct and poorly defined brown marking close to ventral margin of head capsule. Abdominal sternites with irregular white mottling and single spots which become increasingly distinct towards the hinder segments. Meso- and metasternum greyish mid brown and irregularly set with conspicuous white spots. Lateral margins of abdominal tergite VIII whitish, IX with a longitudinal white marking along the lateral margins. Tegmina creamish dark brown with the central hump very dark brown to black. Anterobasal portion of tegmina broadly white. Costal region of alae plain yellowish or greenish pale to mid brown, with a broad white longitudinal stripe along the anterior margin which terminates about ¼ off the base. Anal region transparent greyish brown with brown veins. Ventral surfaces of legs with ± distinct white mottling; apices of all femora and tibiae whitish. Complete armature of the legs black. Antennae plain orange mid brown. Eyes reddish brown.

Head: Generally as in ♀♀, but eyes much more prominent and projecting hemispherically; their length contained less than 2x in that of cheek. Antennae projecting over posterior margin of abdominal tergite II, otherwise as in ♀♀.

Thorax: Pronotum narrower and shorter than head, slightly widened towards the posterior and about 1.5x longer than wide, otherwise as in ♀♀. Mesothorax almost 2x longer than wide and slightly widened at posterior margin. Mesonotum parallel-sided and with a very indistinct longitudinal median carina. Mesosternum with a shallow longitudinal median carina. Metasternum smooth. Tegmina oval, narrowed towards the base and broadly rounded posteriorly; central hump prominent and conical. Alae reaching about half way along abdominal tergite VI.

Abdomen: Median segment almost 2x longer than metanotum, gently narrowing towards the posterior. Segments II–VI ± 3.6x longer than wide, parallel-sided. VII about 2/3 the length of VI, constricted medially and slightly dilated posterolaterally. VIII slightly longer than VII, strongly swollen and broadening towards the posterior, almost 2x wider than VI. IX as long as VIII, distinctly constricted medially and anterior margin almost 2x broader than posterior margin. Anal segment a little shorter than IX, strongly laterally compressed and tectiform. Semi-tergites tapered and gently down-curving in their apical half; apex narrow and rounded (Fig. 220). Interior surfaces of semi-tergites apically densely covered with minute black teeth. Cerci cylindrical, gradually tapered towards a rather acute apex and slightly in-curving; almost reaching apex of anal segment. Poculum very bulgy, strongly convex and cup-like, marginated posteriorly and with a blunt backward pointing central spine.

Legs: All moderately long and slender. Profemora longer than head, pro- and mesonotum combined, mesofemora slightly longer than pro- and mesonotum combined, metafemora reaching about half way along abdominal segment V and metatibiae reaching to posterior of tergite IX. Anterodorsal carina of profemora with 7–17 distinct triangular teeth, posteroventral carina with a somewhat smaller number of slightly smaller and more slender teeth. The posterodorsal carina of profemora occasionally set with at best 6 minute teeth. Mid and hind legs with all carinae sparingly and rather minutely dentate; the teeth more numerous on the ventral carinae. Medioventral carina of meso- and metafemora with 5–12 small but pointed spines. Posterodorsal carina of meso- and metatibia forming a conspicuous, rounded and dentate lobe apically and often with a ± enlarged and broadly triangular tooth pre-medially. Probasitarsus distinctly longer than remaining tarsomeres combined, all carinae gently and uniformly elevated but unarmed. Mesobasitarsus slightly shorter, metabasitarsus a little longer than combined length of remaining tarsomeres; Dorsal carinae gently rounded and smooth or minutely dentate; ventral carinae dentate.

Variation: ♀♀ in particular show considerable variation concerning to the size, colouration, size of the two spiniform tubercles of the vertex and degree of leg armature. A captive reared ♀ in coll. FH (No. 0142-15) is remarkably small, measuring a body length of only 151.0 mm. As the small size may have been caused by insufficient breeding conditions or alternative foodplants used it is not designated a type and excluded from the table of measurements below. One ♀ PT in the first author’s collection (coll. FH, No. 0142-5) has the complete dorsal body surface furnished with irregular, large pale yellowish markings. Another PT in the same collection (coll. FH, No. 0142-7) has the tubercles of the vertex very weakly developed and only represented by pair of shallow and blunt humps.

♂♂ show variation only concerning to the number and degree of leg armure and presence or absence of a enlarged pre-median teeth on the posterodorsal carina of the meso- and metatibiae.

Eggs (Figs. 161–162, 357, 415): Medium-sized to large, capsule strongly rounded but slightly longer than high and conspicuously narrowed posteriorly. General colouration of capsule and micropylar plate creamish grey, operculum black, capitulum dull reddish brown (Fig. 415). Lateroventrally with a very prominent and well defined black marking. Capsule surface shiny and very minutely granulose (40x). Micropylar plate more than ¾ the length of capsule, shaped like an elongate inverted “Y”. Apices of all extensions rounded, outer margin blackish brown. Micropylar cup placed in posteromedial gap of plate, indistinct and posteriorly bordered by a slightly curved ridge. Median line indistinctly raised, very slender and almost reaching polar-area. Polar-area with an oval blackish marking and a small, blunt spine in the centre. Operculum slightly oval, almost flat. Capitulum very large, at least 2/3 the width of operculum, irregularly conical and with numerous carinae and impressions. Stalk short, white.

Measurements [mm]: Length including capitulum 4.8–5.6, length 3.8–4.8, width 3.1–3.8, height 3.5–4.2, length of micropylar plate 3.0–3.8.

Comments: Seen from the numerous specimens available T. siamensis spec. nov. appears to be quite common in Northern and Central Thailand. The record “ Cochinchina ” based on a ♀ in MNHN appears doubtful although the specimen clearly represents T. siamensis spec. nov. In the early 1990’s culture-stock was imported to Europe originating in Chiang Mai (N-Thailand) and subsequently included on the Phasmid Study Group culture-list as culture No. 197. Oaks ( Quercus robur , Q. petraea , Q. rubra , Fagaceae ) and bramble ( Rubus fruticosus , Rosaceae ) are readily accepted as alternative foodplants, but the species has proven rather difficult to maintain in culture.

* including median segment

Distribution (Fig. 406): North and Central Thailand (Dansai Loei; Lamphun: Maetha; Petchabun: Lemgao; Chiang-Mai & Province Khon Kaen: Phu Wiang, Tam Phra 250 m) and N-Vietnam (Hoabinh). S-Vietnam ( Cochinchina) [with doubt].

Number of specimens examined: 42