Trachythorax maculicollis ( Westwood, 1848 )

Bresseel, Joachim & Constant, Jérôme, 1893, Review of the Oriental stick insect genus Trachythorax Redtenbacher, 1908 with two new species from Vietnam and comments on egg parasitism and morphological counteradaptations (Phasmida, Lonchodidae, Necrosciinae), Belgian Journal of Entomology 120, pp. 1-56 : 41-44

Trachythorax maculicollis ( Westwood, 1848)

( Figs 28–29 )

Phasma (Necroscia) maculicollis WESTWOOD, 1848: 77 , plate 38: 2 [described and figured].

Calvisia atrosignata BRUNNER VON WATTENWYL, 1893: 85 , plate 3: 27 [described and figured]. Synonymised by SEOW-CHOEN (2017).

Marmessoidea conspersa REDTENBACHER, 1908: 515 [described]. Synonymised by SEOW-CHOEN (2017).

Necroscia maculicollis – WESTWOOD, 1859: 155 [redescribed].

Calvisia maculicollis – KIRBY, 1904: 369 [catalogued]. — REHN, 1904 [recorded from Thailand].

Trachythorax maculicollis – REDTENBACHER,1908: 508, plate 26: 3 [redescribed, transferred to Trachythorax ]. — SCHULTEN, 1995: 60, fig. 32 [rearing]. — SELLICK, 1998 [egg structure]. — CLIQUENNOIS, 1999: 52 [recorded from Bangladesh], figs 18–19 [female and mating pair], 23 [egg]. — BAXTER, 2002: 89 [rearing, egg]. — OTTE & BROCK, 2005: 336 [catalogued]. — HARMAN, 2012: 16 [origin of culture stocks]. — BROCK et al., 2016: 181 [catalogued]. — MAOSHENG, 2016: 143 [in Singapore]. — SEOW-CHOEN, 2017: 88, figs 74–75 [in Singapore]. — SEOW-CHOEN, 2018: 392, figs 306–309 [in Sumatra].

Trachythorax maculicollis maculicollis – GAO & LIANG, 2021: 1 [as subspecies, in key to Chinese species].

Trachythorax atrosignatus – REDTENBACHER, 1908: 504 [redescribed, transferred to Trachythorax ]. — VANSCHUYTBROECK & COOLS, 1981: 10 [material in RBINS collection, in Vietnam, Thailand & Java]. — CAI, 1989: 323 [in China]. — BROCK, 1998: 16 [type data]. — BROCK, 1999: 121, fig. 180 [as valid species]. — OTTE & BROCK, 2005: 336 [catalogued]. — CHEN & HE, 2008: 179 [in China].

Trachythorax atrosignata – HENNEMANN et al., 2008: 40 [in China].

Marmessoidea conspersa – BROCK, 1998: 23 [type data, lectotype, synonym of T. atrosignata ].

ADDITIONAL MATERIAL. CAMBODIA: 2♂♂, 2♀♀: Kampong Speu, Phnom Aural W.S., nr. Srae Ken vill., 10–14. V .2018, 200–400m, 11°59’N 104°08’E, GTI project, leg. J. Constant & P. Limbourg, I.G.: 33.732 ( RBINS); 3♂♂: ex breeding Tim Bollens , 2018 : Kampong Speu, Phnom Aural W.S., nr. Srae Ken vill., 10–14. V .2018, 200–400m, 11°59’N 104°08’E, GTI project, leg. J. Constant & P. Limbourg, I.G.: 33.732 ( RBINS); 5♂♂, 5♀♀: ex breeding Tim Bollens , 2019 : Kampong Speu, Phnom Aural W.S., nr. Srae Ken vill., 10–14. V .2018, 200– 400 m, 11°59’N 104°08’E, GTI project, leg. J. Constant & P. Limbourg, I.G.: 33.732 (3♂♂, 3♀♀: RBINS; 1♂, 1♀: RUPP; 1♂, 1♀: VNMN); 1♂ : Koh Kong prov., Tatai , 11°35’13”N 103°05’50”E, 27.VII.2016, day collecting, Leg. G. Chartier ( RBINS); 2♂♂, 1♀ : Mondulkiri Prov., Keo Seima Wildlife Sanctuary nr O Pam station , 12°11’39”N 107°01’01”E, 14– 24.XI.2018, leg. J. Constant, I.G.: 33.919 ( RBINS) .

VIETNAM: 10♂♂: Nge An Province, Pu Mat National Park , 18°59’N 104°40’E, 4-9.VII.2017, night collecting, GTI project, leg. J. Constant & J. Bresseel, I.G.: 33.498 ( RBINS) ; 3♂♂: Dong Nai Biosphere Res. 11°18’N 107°06’E, 25.vi–6.vii.2012, night collecting, Leg. J. Constant & J. Bresseel, I.G.: 32.161 ( RBINS) ; 5♂♂, 1♀: VinhPhuc pr., Melinh B.S., 21°23’38”N 105°42’56”E, 30. VI –1.VII.2015, night collecting, Leg. J. Constant & J. Bresseel, I.G.: 33.092 ( RBINS) ; 1♂, 1♀: Con Dao N.P., Con Son Isl. , 08°41’30”N 106°38’00”E, 17–24. VI.2012, day collecting, Leg. J. Constant & J. Bresseel, I.G.: 32.161 ( RBINS) ; 1♂, 2♀♀: Tonkin, Than Moi, Juni – Juli, H. Fruhstorfer ( RBINS) ; 14♀♀: Than Moi, Tonkin, 2–3000, IV– V, H. Rölle, Berlin, S.W. 11, ex. coll. Le Moult ( RBINS) ; 1♂, 5♀♀: Than Moi, Tonkin, ex. coll. Le Moult, I.G. 18.487 ( RBINS) ; 4♂♂, 9♀♀: Annam, Phuc-Son, nov.–dez., H. Fruhstorfer ( RBINS) ; 1♀: Chapa, Tonkin, Collection Le Moult , Naturaliste Paris ( RBINS) .

THAILAND: 1♂, 1♀: Loei prov., Na Haeo, 16. V .2003, Leg. J. Constant & K. Smets ( RBINS) ; 1♂, 1♀: Bangkok, P. Rolin ( RBINS) .

PHOTOGRAPHIC RECORDS. CAMBODIA: mating pair ( Fig. 28 A ): Kampot, 10°36′N 104°10′E, 12.III.2009, R. Overtoom .

INDIA: mating pair: Assam, Karimganj, Dosdewa forest trail, 24°21'10"N 92°20'41"E, 11.IV.2020, iNaturalist user rejoicegassah https://www.inaturalist.org/observations/44459807 .

MALAYSIA: mating pair: Kelantan, Kota Bharu , 6°06'16N 102°15'05"E, 4.III.2021, iNaturalist user izzati1 https://www.inaturalist.org/observations/70554087 .

DIAGNOSIS. The type-species of Trachythorax with males much smaller than females and characterised by the pattern on the head, pro- and mesonotum and by the peculiar pink inflatable membrane between the pronotum and the head (this last feature not always visible in dried specimens). Head with a pair of black spots between the eyes followed by a median black spot dorsally; behind the eye with two longitudinal black stripes. Pronotum with prozona with a pair of elongate oval black spots; metazona with four elongate oval black spots, median pair often less distinct than outer pair. Mesonotum with a lateral black stripe in the anterior half; posterior half with two markings laterally, anterior one small and more or less oval, posterior one distinctly bigger and slightly elongate. Females with a pair of humps almost medially on the mesonotum.

NOTES. The species was originally described from Silhet, Assam. Today Silhet is known as Sylhet and lies in Bangladesh, close to the Assam border. The species seems to be extremely widespread over Southeast Asia making it one of the most widespread species of stick insect in this region and even on a global point of view. There seems to be some geographical variation to a certain degree, but always with the combination of characters presented in the diagnosis above. The markings on head and thorax can sometimes be less distinct but are always present .

The head shape shows a certain degree of variation. In most cases, like in the type-series, it bears a conical elevation posteriorly, with the cone directed upwards. However, this elevation can be less distinct or even absent; in the latter case, the back of the head only being convex. Morphometrics of the wings of specimens from different localities also show small but stable differences (Bresseel & Constant, personal observations).

MAOSHENG (2016) and SEOW-CHOEN (2017) recently reported the species from Singapore based on the same record. BROCK (1999) doubted its presence in Peninsular Malaysia. The recorded specimen is peculiar for having the markings on head and pronotum as well as the profemora green instead of black and the lateral markings on the mesonotum black. A picture on iNaturalist from Kelantan, Malaysia shows the same “aberrant” colouration and more research is needed to confirm whether these records truly represent T. maculicollis .

The synonym T. atrosignatus ( Brunner von Wattenwyl, 1893) , synonymised by SEOW-CHOEN (2017), shows no clear morphological differences, and has the exact same markings on the head, pro- and mesonotum. The synonymy of T. conspersa ( Redtenbacher, 1908) , synonymised by BROCK, 1998, warrants further research. The species was described from the Nicobar Islands, but without additional material at hand it is hard to confirm if this species is actually T. maculicollis . Therefore, it is here retained as a synonym. Trachythorax illaesa ( Redtenbacher, 1908) stat. rev. comb. nov., synonymised by BROCK & DELFOSSE (2005) differs from T. maculicollis by the markings on the head, pro- and mesonotum. It is therefore here reinstated as a valid species (see comment under T. illaesa ).

DISTRIBUTION. ( Fig. 29 ). The species is widespread in Southeast Asia, with historical records from India, Bangladesh, Myanmar, Thailand, China, Vietnam, Singapore, Sumatra and Java.

New records show that this species is widespread in Vietnam, from Sa Pa (“Chapa”), Lao Cai Province in the north to the Con Son Archipelago in the South. The species is recorded from Cambodia for the first time.

Figures

Fig. 28. Trachythorax maculicollis (Westwood, 1848) from Cambodia. A, mating pair, Kampot, 12.III.2009. © R. Overtoom. B–G, Kampong Speu prov, Phnom Aural, ex breeding T. Bollens. B, ♂, dorsal view. C, mating pair, lateral view. D, ♂, head and thorax, dorsal view. E, ♀, head and thorax, dorsolateral view. F, ♀ terminalia, dorsal view. G, newly hatched nymph. B–E, G. © T. Bollens. F. © J. Constant.

Fig. 29. Trachythorax maculicollis (Westwood, 1848) distribution map with data from specimens in RBINS.