Clitumninae Brunner v. Wattenwyl, 1893

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 : 62-64

Clitumninae Brunner v. Wattenwyl, 1893

Type genus: Clitumnus Stål, 1875: 9 .

Clitumnidae Brunner v. Wattenwyl, 1893: 87.

Bruner, 1915: 37.

Ramulinae Kevan, 1982: 382.

Description: Medium sized to very large (body length 28.0–357.0 mm), stick-like, slender to extremely slen- der and often very elongate Phasmatodea (Figs. 76–78). Body cylindrical in cross-section and of ± uniform width. ♀♀ apterous, ♂♂ may be brachypterous or alate. Ocelli lacking. Gula present. Antennae at best 3/5 the length of body, but mostly conspicuously shortened and often just a little longer than head and pronotum combined; with less than 35 segments. Mesothorax mostly very elongate; in a very few cases just a little longer than head and pronotum combined; rarely granulose or spinose. Median segment distinctly shorter (majority of taxa), equal in length, or slightly longer than the metanotum (a few alate ♂♂). Abdominal tergite VII often with a lateral lobe or expansion (♀♀ in particular). Sternum VII of ♀♀ with a ± distinct praeopercular organ; formed by a posteromedian scale-like structure, hump, or pair of spines or lobes. Gonapophyses of ♀♀ elongated in certain taxa, but never projecting considerably over apex of abdomen. Subgenital plate of ♀♀ boatlike, distinctly longitudinally keeled and variable in length; ranging from small, scoop-shaped and not reaching the apex of anal segment, to strongly elongated and lanceolate. Anal segment of ♂♂ laterally compressed, slightly tectiform and consisting of two semi-tergites, which have the apex ± elongated and finger-like, slightly in-curving and the interior surface armed with numerous small teeth ( Figs. 20–25, 29–31, 35–36, 40– 41). External vomer of ♂♂ lacking in a majority of taxa; a rather slender, papillate or filiform external vomer may however be present ina few more derived genera. Supraanal plate usually small and considerably shorter than anal segment; rarely elongated and lanceolate. Cerci small and usually shorter than anal segment, cylindrical to sub-cylindrical in cross-section; rarely laterally compressed or slightly lanceolate. Profemora distinctly triangular in cross-section with the two dorsal carinae ± distinctly approaching each other, compressed and curved basally. Posterodorsal carina considerably reduced, anterodorsal carina ± strongly raised and serrate. Medioventral carina very prominent, acutely ledge or lamella-like and strongly displaced towards anteroventral margin ( Figs. 46–47). Mid- and hind legs often with prominent armature (increasingly reduced im more derived forms). Meso- and metafemora trapezoidal in cross-section with dorsal carinae nearing, medioventral carina present. Tibiae trapezoidal to almost triangular in cross-section, the dorsal carinae strongly nearing each another. No area apicalis on tibiae. Basitarsus distinctly longer than following tarsomere.

Eggs: These may be of various shapes and structures, ranging from simply ovoid with a central capitulum to considerably compressed laterally, angulate and bark-like with variable structures on the outer margin of the operculum. A common feature is the open internal micropylar plate with a ± distinct median line.

Comments: Since the tribes Clitumnini Brunner v. Wattenwyl, 1893 and Pharnaciini Günther, 1953 obviously do not belong in the Phasmatidae s. str. (→ 4.) and subfamily Phasmatinae respectively, they together form a separate subfamily of Phasmatidae sensu lato, the Clitumninae . Clitumnidae was first used for a tribe by Brunner v. Wattenwyl (1893: 87) for taxa now in Clitumnini and Pachymorphini (subfamily Pachymorphinae , → 4.6.1). Subsequently, Brunner v. Wattenwyl (1907: 181) re-named the tribe Clitumnini , and as this is an available name and the monophyletic group here proposed ( Clitumnini + Pharnaciini ) includes the type genus Clitumnus Stål, 1875 , Clitumninae is the valid name for the subfamily that contains these two tribes.

Representatives of Clitumninae were predominantly included in the subfamily Phasmatinae by former authors (e.g. Bradley & Galil, 1977). There are however several features of the genital exosceleton and mor- phology of the profemora, which readily distinguish the tribes Clitumnini and Pharnaciini from the subfamily Phasmatinae . These are the small and cylindrical to sub-cylindrical cerci, presence of a praeopercular organ on sternum VII of ♀♀ and profemora, which have the medioventral carina very distinct, ledge-like or lamellate and conspicuously displaced towards the anteroventral carina. The anal semi-tergites of ♂♂ of Clitumninae are of a rather distinct shape and structure if compared to those of Phasmatinae and Phasmatidae s. str. respectively, having the apex ± strongly elongated, finger-like and in-curving with numerous small teeth on their interior surface (= “Dornenfeld”). Moreover, ♂♂ of certain derived taxa possess a well sclerotised, papillate, hook-like or filiform external vomer, never present in Phasmatidae s. str. and Phasmatinae . Differences are also observed in the copulation position of Clitumninae which is less derived than that seen in representatives of Phasmatidae s. str. (= Lanceocercata). ♂♂ either grasp the ♀♀ abdomen on the corresponding anchorage on sternum VII, the praeopercular organ, or in the case an external vomer is present this is inserted into a slit or hole of that organ to hold fast to the ♀ during copulation.

The shape and length of the ♂♂ ’s semi-tergites in many cases shows correlation to the shape of the appendages of the praeopercular organ of ♀♀. In taxa whose ♀♀ have a prominent praeopercular organ that is formed by a pair of lobes or appendages close to the posterior margin of sternum VII, ♂♂ have usually have the semi-tergites conspicuously elongated and finger-like. During the copulation these appendages of the ♀♀ praeopercular organ are grasped and used as an anchorage by the ♂♂, and mostly the shape of the semi-tergites fits very well with the shape of the appendages of the praeopercular organ.

♂♂ of both tribes contained have the external vomer more or less strongly reduced or lacking, mostly due to being functionally replaced by the movable semi-tergites of the anal segment as an anchorage to hold fast to the ♀ abdomen during copulation. However, in certain taxa of Clitumnini the external vomer is developed and seen to be a sclerotised tube-like, papillate or slender, hook-like organ. This appears to have been re-evolved secondarily and functions as an additional anchorage, with the corresponding ♂♂ seen to grasp the praeopercular organ of ♀♀ and insering their vomer into a posterior slit or hole of the same. In certain taxa of Pharnaciini which at first glance appear to lack an external vomer, it can seen to be an elongate and straight tube-like or papillate organ if the semi-tergites are spread and the paraprocts pushed aside ( Fig. 40).

Phasmatini , Acanthomimini , Acanthoxylini (all subfamily Phasmatinae , → 4.3), Pharnaciini and Clitumnini all have profemora that are distinctly triangular in cross-section, having the dorsal carinae strongly approching each other, the posterodorsal carina reduced and the anterodorsal carina more or less strongly raised and ± distinctly serrate. In Tropidoderini and Monandropterini , they are just indistinctly triangular in cross-section, with the dorsal carinae only moderately approaching each other and unarmed. Triangular profemora are however also found elsewhere throughout the Phasmatodea and thus this character cannot be used at a higher systematic rank than at subfamily level. This has led to much confusion since Redtenbacher (1908: 436) mentioned this as the main character to distinguished his Acrophyllini from other “Anareolatae”, which however is clearly an artificial group (→ 3.1). No subsequent author has since recognized the most obvious and characteristic feature of the profemora which serves for distinguishing the subfamilies Phasmatinae and Clitumninae , the structure and position of the medioventral carina. This is conspicuously raised, ledge-like or lamellate, ± in-curving and strongly displaced towards the anteroventral carina in Pharnaciini and Clitumnini (subfamily Clitumninae , Figs. 46–47), but merely a rather indistinct longitudinal keel midways on the ventral surface of the profemur in Phasmatinae (family Phasmatidae s. str., Fig. 44).

As stated above the eggs of Clitumninae are very polymorphic but characteristic for having an open internal micropylar plate and a ± distinct median line (Figs. 54–56). This means, the micropylar cup is placed outside the borders of the plate, usually in a more or less distinct posterior incision or gap. The external plate is usually longer than wide, but may be transverse and does not reach the anterior and posterior poles of the egg capsule. It shows a more or less prominent posteromedian incision or gap similar in shape to that of the internal plate. The external plate is either oval, lanceolate, strongly elongate and parallel-sided, bilobed with an anteromedian indention, or even shaped like an inverted “Y”. The latter shape is atttained by elongation of the posterolateral regions on both sides of the median gap. While the micropylar plate usually covers more than? of the capsule length in Pharnaciini it may be as short as just ¼ of the capsule length in certain Clitumnini . The operculum always bears more or less prominent opercular structures, such as a ± distinctly stalked capitulum ( Pharnaciini , Fig. 54), or a raised crown-like outer margin, hairy structures or pseudocapitulum ( Clitumnini , Figs. 55–56). The capsule is mostly ovoid and longer than wide, more rarely spherical in Pharnaciini and certain Clitumnini . In many Clitumnini however it is very elongate and strongly laterally flattened with the capsule surface unevenly sculptured, giving the egg a bark or grass-seed like appearance. Some genera of Pharnaciini have laterally flattened, lens-shaped eggs, which exhibit a distinct , more or less elevated dorsoventral keel. In general, egg features are observed to be very uniform and rather typical within each individual genus and therefore very well serve for the distinction of genera amongst Clitumninae .

Close relationship between Clitumnini and Pharnaciini not only becomes obvious by the morphological features of the external genitalia and profemora here mentioned but is also emphasized by habitual similarity between taxa of both tribes. The more derived apterous representatives of Pharnaciini in particular strongly resemble certain genera of Clitumnini , the most remarkable example being represented by Baculonistria gen. nov. ( Pharnaciini ) and Entoria Stål, 1875 (Clitumnini) . These two genera are merely distinguished by the key features which distinguish Pharnaciini from Clitumnini , namely the shape of the scapus, leg armature and opercular structures of the eggs. In Baculonistria gen. nov. the scapus is slender, all ventral carinae of the mid and hind legs distinctly serrate and the ovoid eggs bear a prominent, stalked central capitulum, whereas in Entoria the scapus is considerably dilated laterally, the mid and hind legs at best armed with single teeth and lobes or a with few minute basal serrations on the tibiae, and the eggs are laterally compressed, considerably longer than wide and lack a stalked central capitulum. Another example is represented by the very slender ♀♀ of certain species of Phobaeticus Brunner v. Wattenwyl, 1907 with a short subgenital plate, which remarkably resemble ♀♀ of the genera Ramulus Saussure, 1862 or Cuniculina Brunner v. Wattenwyl, 1907.

Pharnaciini certainly inherit the more basal taxa amongst Clitumninae which is in particular seen in the relatively longer median segment of most genera and presence of tegmina and ± well developed alae in the ♂♂ of certain species. Interpreting Pharnaciini as the more basal forms of Clitumninae obviously reveals a loss of wings during the course of evolution of this particular subfamily, and suggests a secondary recovery of the external vomer, since this is only present in certain Clitumnini and the supposedly most derived genus of Pharnaciini ( Baculonistria gen. nov.), but lacking in the more basal Pharnaciini . Evolutional trends recognized within Clitumninae are e.g. a decreasing body size, leg armature and sexual dimorphism, but an increasing elongation of the body segments and legs.

Distribution & Biogeography ( Fig. 1): Complete Oriental Region, southern portion of the Palearctic Region ( China, Korea, Far East Russia & Japan), complete Wallacea and as far east as New Guinea (→ Map 1).

The wide dispersal of Clitumninae in the Indo-Malayan Archipelago appears to have been mainly advanced by the glaciation during the Pleistocene which has caused a decrease of the world-wide sea-level and developed land or island chain bridges between the Asian continent and the Large Sunda Islands. These quite certainly allowed an interchange of the faunas of the Asian continent and Sundaland ( Cox & Moore, 1993). Subsequent diversification and specialization, especially on the Asian continent, becomes obvious in the very speciose and derived Clitumnini .