Tisamenus (insect)



The genus Tisamenus native to the Philippines combines small to medium-sized species of stick insects.

Taxonomy
In 1875 Carl Stål established the genus Tisamenus in addition to the genus Hoploclonia. In this he described the type species determined by William Forsell Kirby in 1904 Tisamenus serratorius. He also transferred two species described by John Obadiah Westwood in 1848 to this genus, namely Phasma (Pachymorpha) deplanatum (today's name Tisamenus deplanatus) and Phasma (Pachymorpha) draconinum (current name Tisamenus draconina). James Abram Garfield Rehn and his son John William Holman Rehn mention in 1939 the special position of the two Hoploclonia species Hoploclonia gecko and Hoploclonia cuspidata, which are already known from Borneo, but synonymized Tisamenus with Hoploclonia. They transferred all previously known Tisamenus species to the genus Hoploclonia, in which they described a further eight species. They created an identification key for the Philippine species and divided them into four subgroups according to morphological aspects. They also described the genus Ilocano for Ilocano hebardi and transferred the species listed as Heterocopus ranarius (current name Tisamenus ranarius) to this genus. In 2004 the two genera were separated again and the Filipino species were transferred back to the genus Tisamenus. Only those occurring on Borneo were left in the genus Hoploclonia. In 2021, a study based on genetic analysis shows that Ilocano hebardi, the only remaining species of this genus at that time, belongs to Tisamenus, whereby Ilocano became a synonym for it. The division into subgroups made in 1939 could not be confirmed for four investigated species known by name. The name "Tisamenus" is the Latinisation of the Greek Tisamenos (Τισαμενός), an ancient, male given name.

Valid species are:
 * Tisamenus alviolanus Lit & Eusebio, 2010
 * Tisamenus armadillo Redtenbacher, 1906
 * Tisamenus asper Bolívar, 1890
 * Tisamenus atropos (Rehn, J.A.G. & Rehn, J.W.H., 1939)
 * Tisamenus cervicornis Bolívar, 1890
 * Tisamenus clotho (Rehn, J.A.G. & Rehn, J.W.H., 1939)
 * Tisamenus deplanatus (Westwood, 1848)
 * Tisamenus draconinus (Westwood, 1848)
 * Tisamenus fratercula (Rehn, J.A.G. & Rehn, J.W.H., 1939)
 * Tisamenus hystrix (Rehn, J.A.G. & Rehn, J.W.H., 1939)
 * Tisamenus hebardi (Rehn, J.A.G. & Rehn, J.W.H., 1939) (Syn. = Ilocano hebardi Rehn, J.A.G. & Rehn, J.W.H., 1939 )
 * Tisamenus kalahani Lit & Eusebio, 2005
 * Tisamenus lachesis (Rehn, J.A.G. & Rehn, J.W.H., 1939)
 * Tisamenus polillo (Rehn, J.A.G. & Rehn, J.W.H., 1939)
 * Tisamenus ranarius (Westwood, 1859)
 * Tisamenus serratorius Stål, 1875
 * Tisamenus spadix (Rehn, J.A.G. & Rehn, J.W.H., 1939)
 * Tisamenus summaleonilae Lit & Eusebio, 2005
 * Tisamenus tagalog (Rehn, J.A.G. & Rehn, J.W.H., 1939)

Description
The representatives of this genus are consistently small to medium-sized with 2.5 to 4.5 cm in the male and 3.0 to 6.7 cm in the female sex. Both sexes are wingless. The often very similar species differ mainly in their species-specific spines. There are also species that have no or barely recognizable spines. A triangular structure on the mesonotum is characteristic of all representatives. The short side of this isosceles triangle runs parallel to the leading margin of the mesonotum. The other two sides are longer and meet more or less after a third of the mesonotum length, depending on the species. From there a mostly clear keel runs in the middle. In some species this begins at the front margin of the mesonotum and can therefore also be recognized on the triangle. Sometimes it extends to the abdomen or even to the end. Spines are often found on the lateral margins of the thorax, in pairs on the pronotum, and in the middle of the meso- and metanotum. Many representatives also have additional paired and/or centrally arranged spines on the abdomen. The color is mostly dominated by light brown tones. Often, black, light brown to beige patterns can be found, less often even almost white patterns. Males are usually less patterned. When looking at them from above, they often notice their abdomen, which is apparently much too narrow. This is especially true for species whose thorax becomes wider and wider towards the metanotum. The proportions of the females appear more symmetrical, as the abdomen is always wider than that of the males. As is typical for the representatives of the Obriminae, they have a secondary ovipositor at the end of the abdomen for laying the eggs in the ground, which is rather short in Tisamenus females. It surrounds the actual ovipositor and is ventral formed from the eighth sternite, here called subgenital plate or operculum and dorsally from the eleventh tergum, which is referred to here as the supraanal plate or epiproct.

Way of life and reproduction
The nocturnal animals hide near the ground during the day. Even at night they hardly climb higher than 20 cm on the food plants. The eggs are laid in the ground by the females with the ovipositor. They are 4 to 5 mm long and 2.5 to 3.0 mm wide and usually covered with more or less clear lines of hairs. The micropylar plate has three arms and resembles an upside-down "Y". The arm pointing to the lid (operculum) is significantly longer than the arms pointing to the lower pole. The nymphs hatch after 4 to 6 months and need 5 to 7 months to become adult.

In terraristics
In the terrariums of the enthusiasts, in addition to some species that have already been identified, there are many previously scientifically unprocessed breeding stocks. The first animals of the genus which were bred in Europe were collected in 2009 by Joachim Bresseel and Thierry Heitzmann in the Quezon on Luzon. Locations are the Sierra Madre mountains near Real and Real itself. Bresseel, Rob Krijns and Tim Bollens found more animals in 2010. The animals first came to Europe as Tisamenus sp. 'Sierra Madre' or Tisamenus sp. 'Real'. The species was later identified by Bresseel as Tisamenus serratorius. The Phasmid Study Group lists them under PSG number 314.

At the end of November 2008, Heitzmann collected a female in the Quezon National Park from which another breeding stock can be traced back. Specimens of this stock are called Tisamenus sp. 'Quezon National Park', according to initial assessments, it also belongs to Tisamenus serratorius Bressell, Bollens and Mark Bushell also found other specimens on Luzon in the province Aurora near the city San Luis in Cunayan. These are also similar to Tisamenus serratorius, but have more or clearer spines, especially along the middle of the body. They are also named after where they were found and called Tisamenus sp. 'Cunayan'. The Phasmid Study Group gave them the PSG number 359.

In October and November 2010, Heitzmann found Tisamenus deplanatus in southern Luzon in the Pocdol Mountains on Mount Pulog and on Mount Osiao. The resulting breeding stock is called Tisamenus deplanatus 'Pocdol' and received PSG number 399 from the Phasmid Study Group. In 2014, Heitzmann again collected other, very similar animals in the Ilocos region. They are called Tisamenus sp. 'Ilocos' or following a more recent designation as Tisamenus fratercula 'Ilocos' and listed under the PSG number 391.

At the beginning of June 2014, Albert Kang brought animals from the island of Sibuyan that were initially named and distributed as Tisamenus sp. 'Sibuyan'. Frank H. Hennemann identified it as Tisamenus hystrix in 2023. Another breeding stock goes back to two very differently colored females that Heitzmann and Kang collected on November 5, 2014 in a protected area near the Callao Cave in the province of Cagayan. From the eggs laid by these females, a sexual stock could be established, which was called and distributed as Tisamenus sp. 'Cagayan'. It is one of the most widespreaded species of the genus. A stock, initially called Tisamenus sp. 'Palaui' comes from the island Palaui, which also belongs to the province of Cagayan. It is similarly spiny to Tisamenus sp. 'Cagayan', but clearly more contrasting and intensely colored. Characteristic of this species is an orange color in the females and an almost reddish color in the males. The species was identified by Hennemann in 2023 as Tisamenus draconinus, so the stock must be referred to entirely as Tisamenus draconinus 'Palaui'.

From Camarines Norte comes a stock which, according to Bank et al., belongs to Tisamenus clotho. It was initially called Tisamenus cf. clotho 'Camarines'. Not in breeding is Tisamenus hebardi which was initially known as Tisamenus sp. 'Ifugao and later called Ilocano hebardi 'Sagada', which was first collected by Heitzmann and Kang in October 2013 and in April 2014 by Heitzmann, Bresseel and Jérôme Constant in the cloud forest on Mount Polis.

The keeping and breeding of most of the species mentioned is considered easy. They willingly feed on various forage plants such as bramble, hazel, firethorn, ivy and Hypericum. They only need small, moderately moist terrariums with a substrate for laying eggs.