Orestes mouhotii is an insect species belonging to the order of Phasmatodea. Because of its synyonym Orestes verruculatus, it is the type species of the genus Orestes. Because of its compact body shape, the species is sometimes referred to as small cigar stick insect.
Characteristics The females are 45 to 55 millimetres (1.8 to 2.2 in) long and thus longer than the maximal 40 millimetres (1.6 in) long males. Both sexes have noticeably short legs and have beige to brown patterns. The males wear semicircular horns (auricles) on their head. While they are overall thinner and are characterized by a slightly thickened end of abdomen, the more compact females have a typical thickening immediately behind the middle of the abdomen, which is especially recognizable as the height increases. Freshly adult females are very vividly drawn light and dark brown and often have light, almost white areas, especially on the sides and in the middle of the abdomen. Over the middle of the body there is usually a particularly distinct dark brown longitudinal band on the front abdomen and the metanotum, which is somewhat lighter on the mesonotum and is flanked here by black-colored tubercles. This high-contrast drawing fades with increasing age and the insects become increasingly uniformly light brown.
Way of life and reproduction During the day, the insects put their hind legs back and the middle legs stretched forward close to the body. At the same time, the fore legs and the antennae are stretched forward. In this position, the phytomimesis is so perfect that the insects can hardly be distinguished from a short, broken branch. At night they feed on food plants, which includes Curculigo species, Dioscorea species like Dioscorea glabra, Dracaena species like Dracaena fragrans and Dracaena surculosa as well as Epipremnum species. The females begin about two months after the moult for the imago to lay the eggs one by one, about 3 millimetres (0.12 in) long, 2 millimetres (0.079 in) wide and an average of 14 milligrams. The nymphs hatch from the eggs after just two months. They need about a year to develop into an imago. The life expectancy of adult females is also another year. The species reproduces by parthenogenesis (female-only asexual reproduction), cyclically, so natural populations are generally exclusively female. Males are rare even in sexually reproducing populations and occur in a ratio of 1 to 20.
Taxonomy
The species was described in 1865 by Henry Walter Bates as Acanthoderus mouhotii. Bates chose the species name in honor of the French Southeast Asia traveler Henri Mouhot. As holotype a subadult female from Thai Chantaboun is deposited in the University of Oxford. In 1875 Carl Stål transferred Acanthoderus mouhotii and Acanthoderus oileus to the genus Datames which he specially established for these two species. Whose type species Datames oileus, established by James Abram Garfield Rehn in 1904, was later transferred to the genus Pylaemenes and the genus Datames was synonymized with this in 1998. For Orestes mouhotii the name Pylaemenes mouhotii was partly used around the turn of the millennium (1998 to 2000) In 1906 Josef Redtenbacher described a new species under the name Orestes verruculatus in a genus specially established for this. He also chose a subadult female as their holotype. It was collected in Bangkok and is deposited in the National Museum of Natural History, France in Paris. Orestes verruculatus, as first described species even the type species of Orestes, was synonymous with Orestes mouhotii by Oliver Zompro in 2004. In result the valid name is Orestes mouhotii and consists of the genus name of the synonymized Orestes verruculatus and the species name of first described species. The newly combined name Orestes mouhotii was first used as early as 1999 by Ingo Fritzsche and used later in the same year by Zompro and Fritzsche. Although Zompro is the first author of one of the 1999 papers, he prioritized 2004 a work published by him in 2000 as the first mention of Orestes mouhotii. But an article published in 2000 not cited in 2004 fitting as a source. Franz Werner described in 1934 with Dares fulmeki a species which was already synonymous in 1935 by Klaus Günther with Datames oileus (today valid name Pylaemenes oileus). Paul D. Brock assigned Dares fulmeki in 1998 to Datames mouhotii and thus made this species another synonym of Orestes mouhotii in today's sense. The holotype of Dares fulmeki is an adult female from Medan (Sumatra) in the Natural History Museum Vienna. As genetic analysis by Sarah Bank et al show, Orestes mouhotii forms within the genus Orestes together with Orestes draegeri and another undescribed species from the Andamans, called Orestes sp. 'Andaman', a clade of very similar species. In all of them, the males have two almost semicircular horns (auricles) on their head, while the females have a flat head without any major elevations. The sister species of Orestes mouhotii is therefore the species from the Andamans. Joachim Bresseel, who co-authored the taxonomic classification of the species, only refers to the animals from the Kirirom National Park in Cambodia as Orestes mouhotii. All other investigated populations are assigned to Orestes draegeri. This assignment can only be valid if the holotype of Orestes mouhotii, as well as the holotypes of the two synonyms, prove to be identical to the species originating from the Cambodian Kiriom. Otherwise the animals from Kiriom would be a different species and Orestes draegeri would be a synonym. Francis Seow-Choen takes in 2018 the view that all of him in Phuket, on Malay Peninsula and in Singapore examined animals are represantitives of Orestes mouhotii.
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