Tisamenus malawak, 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 : 56-58

Tisamenus malawak n. sp.

( Fig. 32)

ZooBank: https://zoobank.org/ 8760796D-3665-4F76-9E36-75B6A9C1CF1B

Tisamenus sp. 9 (Camiguin), Bank et al., 2021: figs 6-7.

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

Differentiation. – The ♂ of this small and stocky new species (the only sex known) is morphologically closest to T. alviolanus Lit & Eusebio, 2010 from Negros and T.cervicornis Bolívar, 1890 from Luzon, but can readily be separated from these two species as from all other other members of Tisamenus by the very broad general shape and relatively much shortened body segment with the mesothorax being notably shorter than it is wide at the posterior margin ( Fig. 32 A-D). Moreover, the head and body armature is less developed, the meso- and metapleural supra-coxals are ca. 45° backward directed and geographically it is separated by being only known from the small island of Camiguin north off Mindanao.

Etymology. – The name of this new species ( malawak Filipino = broad, wide) refers to the remarkably stocky shape of this small species, in whose ♂ the mesothorax is notably shorter than the width of that segment at its posterior margin, a unique morphological state within the entire genus.

A. Dorsal view. B. Dorsolateral view. C. Ventral view. D. Closeup of head, pro- and mesonotum. E. Closeup of head, pro- and mesosternum. F. Terminalia in lateral view. G. Terminalia in dorsal view. H. Terminalia in ventral view.

Description

♂ ( Fig. 32)

Form and colouration. – Size small for the genus (body length 29.0 mm);general form very heavy and broad, legs short and strong with the meso- and metafemora distinctly incrassate; elements of armature rather moderately developed. Meso- and metathorax strongly gradually widening towards posterior and together forming a trapeziform unit; body surface unevenly granular. General colour reddish fuscous dorsally, the ventral body surface rather buff to walnut brown; medio-longitudinal dorsal keel of thorax and all larger elements of thoracic armature russet, the teeth and spines of abdomen and limbs as well as the medio-longitudinal carina of mesosternum ochre.Ten terminal antennomeres glossy, the basal joints drab.

Head. – Sub-quadrate, a little wider than long with the genae weakly convergent. Entire armature rather weakly developed; the three supra-orbitals moderately conical, tuberculate with the median one largest; occipitals and coronals rather low, tuberculate ( Fig. 32H). Three gulars small and nodose. Vertex with coronal line slightly indented. Eyes of average size, moderately globose and their diameter corresponding to scarcely less than half the length of gena.Antennae strong with the basal half perlamorph and consisting of 24 joints;scapus roundly triangular in dorsal aspect, pedicellus about half aslong and cylindrical; III slightly longer than pedicellus, IV very short, transverse and only one-third the length of III; III-X sub-globose and somewhat increasing in length, XI-XXIII very slightly decreasing with the terminal antennomere notably elongated and almost as long as two preceding joints taken together.

Thorax. – Pronotum sub-trapeziform, notably wider than long; triangular area fairlydistinctwith marginsunevenly tubercular and the anterolateral angles witha strong andobtusebifidtubercle;discotherwiseshallowlynodoseandthe posteriors somewhat enlarged and weakly tubercular. Mesothorax strongly widening towards posterior, distinctly trapezoidal in outline with width at posterior margin notably greater than length; almost 2x longer than prothorax and with posterior portion 1.5x wider than anterior margin. Mesonotum elongate, posterior half narrowedandlateral margins distinctly constricted post-medially; about 1.6x longer than width at anterior margin. Mesonotal triangular area small, scarcely more than one-third as long as notum and a little shorter than width across anterolateral angles, disk weakly indented with some nodes along the median line, the converging outer margins unevenly granular and anteriorly protruded into a n obtusely conical swelling; the anterior margin with a pair of low anterior mesonotals ( Fig. 32H). Posterior portion of mesonotum with a distinct medio-longitudinal keel that is covered by two rows of low, shiny granules. Mesopleurae strongly expanding towards the posterior and triangular in dorsal aspect, the lateral margins densely granular and the four laterals merely represented by low rounded nodes (antero-lateral slightly tubercular); an irregular medio-dorsal longitudinal row of nodes present; mesopleural a rather strong somewhat posterior directed and simple, conical tubercle. Metanotum roundly trapezoidal in outline and with the same medio-longitudinal keel seen on mesonotum, bearing two rows of shiny granules. Metapleurae strongly expanded with laterals sub-obsolete, the metapleural somewhat more pronounced and the migrated supra-coxal angle with a strong but short bifid and somewhatposterior directed supra-coxal tubercle.Probasisternum with a widely spaced pair of low but distinct nodes ( Fig. 32I). Mesosternum distinctly tri-carinate with the lateral carinae somewhat arched and irregular; between mesocoxae with a prominent, gibbose and minutely granular swelling. Metasternum only with a faintly indicated medio-longitudinal carina ( Fig.32I).

Abdomen. – Median segment almost semi-circular in outline, carinate medio-longitudinally and with a small node-like pair of first and second paired posteriors (the medio-longitudinal keel like on meso- and metanotum). Segments II-VII slightly decreasing in length and width, all transverse with VII shortest and 2.2x wider than long; II trapeziform.Terga II-IV with a strong pair of second pared posteriors, that is spinose on II and III, tubercular on IV and merely represented by small tubercles on V. The medio-longitudinal carina bi-lineate and granular but rather weak on V-VII. Sterna II-VII with a fine medio-longitudinalcarina, II-IV with alow pair of medial nodes. Tergum VIII wider than VII and almost 3.3x wider than long, IX narrower; both with the medio-longitudinal keel posteriorly protruded into an obtusely dentiform

A. Dorsal view. B. Dorsolateral view. C. Lateral view. D. Ventral view. E. Terminalia in dorsal view. F. Terminalia in ventral view. G: Anteroventral view of left hind leg. H. Closeup of head, pro- and mesonotum.. I. Closeup of head, pro- and mesosternum.

swelling. Anal segment declining and cucullate in lateral aspect, somewhat narrowing towards the posterior with a pair of latero-anterior nodes; lateral margins angular and concave in posterior half; posterior margin with a wide, shallow, bi-concave median emargination and the outer angles obtusely protruded ( Fig. 32E). Epiproct fairly large, transverse, rounded and slightly projecting beyond posterolateral protrusions of anal segment ( Fig. 32E). Vomer very braid, transverse and with a short terminal hook, that is slightly migrated dextrally. Poculum roundly cup-shaped, somewhat narrowing towards the posterior with a broad and labiate posterior flange of the free upper margin, that is very shallowly concave posteriorly and reaches two-thirds the way along anal segment ( Fig. 32F).

Legs. – Short and strong with all the dentations well developed; the femora but metafemora in particular distinctly incrassate. Profemora as long as, mesofemora slightly shorter than mesothorax, metafemora reaching about halfway along abdominal segment VI and metatibiae surpassing tip of abdomen by about the length of anal segment. Profemora with three teeth on posterodorsal carina; meso- and metafemora essentially with four teeth on each of the four carinae, the ventral ones of which are somewhat large and more spinose. Dorsal teeth of metafemora decreasing in size towards apex of femur, the two apical ventral ones spinose; ventro-basal swelling of metafemora distinct, sub-globose and smooth ( Fig. 32G). All tibiae smooth dorsally; pro- and mesotibiae with single dentiform ventral swellings, metatibiae with three rather distinct triangular teeth on ventral carinae ( Fig. 32G). Basitarsi short and just slightly longer than following two tarsomeres taken together.

Measurements of holotype [mm]. – Body 29.0, pronotum 3.2, mesonotum 5.7, metanotum 3.2, median segment 1.7, profemora 6.0, mesofemora 5.0, metafemora 6.4, protibiae 5.9, mesotibiae 4.9, metatibiae 6.6, antennae 10.5.

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. 9 (Camiguin)”. Thus, the specimen lacks the left mid leg ( Fig. 32 AVD). Female and egg unknown.

Distribution. – Camiguin, endemic [RBINS – type locality].