Tisamenus heitzmanni, Hennemann, 2025

Hennemann, Frank H., 2025, A taxonomic review of Philippine Obrimini stick insects: The genus Tisamenus Stål, 1875 (Insecta: Phasmatodea: Heteropterygidae: Obriminae), Faunitaxys 13 (24), pp. 1-85 : 40-42

Tisamenus heitzmanni n. sp.

( Fig. 22)

ZooBank: https://zoobank.org/ A383FD8E-4306-472E-B746-5BAD22CB27B3

Tisamenus sp. 8 (Cebu), Bank et al., 2021: Fig. 6-7.

HT, ♂: Cebu, Philippinen, leg. Heitzmann, 2014 [ ZMK, ex coll. TB] .

Differentiation. – The ♂ of this new species (the only sex known) is morphologically very close to T. hystrix ( Rehn & Rehn, 1939) from the island of Sibuyan but differs by the stockier shape and relatively shorter body segments with the mesonotum being only 2x longer than wide (almost 2.5x in hystrix ), more gradually broadening mesothorax, having six instead of five very strong mesopleural spines, lacking the strong pair of inter-posterior meso- and metanotals and pair of spines on the median segment as well as abdominal terga IV and V seen in A -G. ♂ from mossy forest at 2000 m on Mount Polis, Sagada, Mountain Province, North Luzon [ RBINS]. A. Dorsal view. B. Dorsolateral view. C. Lateral view. D. Ventral view. E. Terminalia in lateralview. F. Terminalia in ventral view. G. Closeup of head, pro- and mesonotum. H. Live ♂ at Banaue, Ifugao Province, North Luzon [© Albert Kang https://inaturalist.ca/observations/57611612]. I. Live couple at Langawe, Banaue, Ifugao Province, North Luzon [© Albert Kang https://inaturalist.ca/observations/57719470]. J. Penultimate instar ♀ from Banaue, Ifugao Province, dorsal view [ RBINS]. K. Penultimate instar ♀ from Banaue , Ifugao Province, dorsolateral view [ RBINS] .

hystrix , basally more incrassate metafemora and presence of distinct ventral teeth of the metatibiae (metatibiae unarmed in hystrix ). The ♀ is only known from a photograph of a live specimen taken at Nug-as Forest Reserve, Sibuyan (https://www.inaturalist.org/observations/ 40873074) and most closely resembles that of T.clotho ( Rehn & Rehn, 1939) in general shape, but can readily be separated by the typical thoracic armature also seen in the ♂, which includes six instead of five mesopeural spines.

Etymology. – Named after Thierry Heitzmann ( Philippines), the collector of this species, for his great efforts in searching for Phasmatodea throughout the Philippines and providing European breeders with numerous culture stocks.

Description

♂ ( Fig. 22)

Form and colouration. – Size small for the genus (body length 32.2 mm); general form rather heavy, legs fairly strong with metafemora moderately incrassate; elements of armature very prominent with strong and pointed meso- and metapleural spines. General colour fuscous with the raised carinae of the thorax and most spines russet and tipped with black, the legs dark buff, the meso- and metasternum slightly lighter in colour with the medio-longitudinal keel tawny and the femora with faint tawny markings ventrally. Antennae drab with the terminal twelve joints shiny and slightly lighter in colour and the terminal antennomere buff.

Head. – Sub-quadrate, scarcely longer than wide with the genae weakly convergenttowardsthe posterior.Anteriorsupra-orbitals large and spinose,the second and third notably smaller and tubercular; occipitals small tubercular; median and lateral coronals larger than occipitals, tuberculate, the lateral coronals weakly bifid ( Fig. 22H). Eyes fairly large, almost hemispherical and their diameter corresponding to about 0.6x length of gena. Genae supplied with two low, nodular gulars.Antennae roughly reaching to tip of protarsi and consisting of 24 joints;scapus slightly triangular in dorsal aspect with interior margin weakly rounded, pedicellus about half the length of scapus and round in cross-section; III notably longer than pedicellus, IV much shorter and sub-globose, the following joint up to XI slightly increasing in length, then very weakly decreasing with the terminal antennomere much elongated and about as long as preceding two joints combined.

Thorax. – Pronotum sub-quadrate with lateral margin gently convex; triangular area moderately developed with convergent margins bounded by small tubercular elements and anterolaterally with a huge bifid spine, whose spikes are gently arched backwards ( Fig. 22H). Mesothorax broad, slightly, gradually widening towards the posterior; about 2.2x longer than prothorax and with posterior portion 1.3x wider than anterior margin. Mesonotum sub-trapeziform with lateral margins very slightly convergent towards the posterior and with a distinct narrowing post-medially; about 1.8x longer than width at anterior margin; the triangular area prominent, slightly surpassing middle of notum, a little longer than wide, disk indented and shallowly concave and the convergent margins shallowly granulate with the anterolateral angles protruded into a large upright spine that is almost as hight as the anterior pronotals ( Fig. 22H); posterior portion of mesonotum with a prominently raised shallowly granulate medio-longitudinal bulge; the posterior portion of the bulge with a closely spaced pair of small, glossy nodes. Mesopleurae notably expanding towards the posterior and armed with five long and strong, spinose laterals, that gradually increase in size from anterior to posterior; mesopleural largest of all mesopleural spines; all gently arched; supra-coxal small and obtusely tubercular. Metanotum trapezoidal with lateral margins weakly convex, a little longer than wide and with the same granulose medio-longitudinal keel seen on mesonotum. Metapleurae with two slender, spinose laterals; metapleural conical, tubercular and the supra-coxal angle with a strong and huge bifid supra-coxal spine /the posterior spike much smaller although). Mesosternum rather faintly tri-carinate with the lateral carinae supplied with a few very shallow node-like mesosternals; metasternum with a shallow medio-longitudinal carina and two small node-like metasternals laterally.

Abdomen. – Median segment strongly trapeziform with anterior margin only half the width of posterior margin, disc distinctly carinate medio-longitudinally. Segments II-VI very slightly decreasing in width and notably decreasing inlength, all transverse withVII roughly 2x wider than long. Terga II-IV with a strong pair of paired second posterior spines, which slightly decrease in size from II towards IV; second paired posteriors only represented by small tubercles on V. All terga shallowly and obtusely tectate medio-longitudinally, the keel protruded posteriorly on VI-IX with the protrusion increasingly raised and dentiform towards IX. Sterna II-VI with a fine medio-longitudinal carina. Terga VIII and IX with node first paired posteriors and shortest of all segments, being wider than VII and roughly 3x wider than long. Anal segment longer than IX, somewhat transverse, declining and narrowed in the posterior section with lateral margins almost rectangular with the angle somewhat deflexed laterally; dorsal surface with an obtuse and low medio-longitudinal bulge and with a pair of nodose anteriors;posterior margin witha broad and very shallow, concave median excavation, the outer angles obtuse and somewhat protruded laterally ( Fig. 22F). Epiproct distinct, shield-shaped, transverse, rounded and somewhat projecting beyond anal segment. Vomer very broad, distinctly transverse, almost symmetrical with a short upcurved terminal hook. Poculum angularly cup-shaped with an obtuse central protrusion at the angle; the free upper margin broadly labiate ( Fig. 22G), somewhat down-curved and shallowly indented posteromedially.

Legs. – All rather stocky with the femora but metafemora in particular somewhat incrassate; all femoral teeth fairly distinct and acute, the two apical ventral ones in particular slender and somewhat spiniform. Profemora scarcely, mesofemora notably shorter than mesothorax, metafemora almost reaching posterior margin of abdominal segment V and metatibiae surpassing tip of abdomen by a little more than length of anal segment. Ventro-basal swelling of metafemora gibbose, smooth ( Fig. 22E); the three teeth of dorsal carinae increasing in size towards base of femur. Metatibiae smooth dorsally and with about six plus a few smaller intercalated rather sharp teeth ventrally. Basitarsi short and a little longer than following two tarsomeres taken together.

Measurementsof holotype [mm]. – Body32.3, pronotum 3.1, mesonotum 6.7, metanotum 3.4, median segment 1.9, profemora 6.4, mesofemora 5.6, metafemora 6.8, protibiae 6.7, mesotibiae 5.8, metatibiae 7.2, antennae 12.5.

Remarks. – The holotype is the voucher specimen of the sample sequenced for the molecular study by Bank et al. (2021) and referred to as “ Tisamenus sp. 8 (Cebu)”. Female and egg unknown.

Distribution. – Cebu, endemic [RBINS – type locality]; Alcoy, Nug-as Forest Reserve [photographic record by Aloke Sahu: https://www.inaturalist.org/observations/40873074].