Tisamenus Stål, 1875

Genus Tisamenus Stål, 1875 View in CoL

Tisamenus Stål, 1875: 50 View in CoL , 92.

Bolívar, 1890: 307.

Kirby, 1904 399. (Designation of type-species)

Redtenbacher, 1906: 43.

Bradley & Galil, 1977: 199.

Zompro, 2004: 206, 322. (Re-established as a valid genus, tribe Eubulidini )

Otte & Brock, 2005: 334.

Lit & Eusebio, 2005b: 208.

Lit, 2020: 326. (Key to species of Deplanatus Group)

Bollens et al., 2010: 10.

Hennemann et al., 2016: 19. (Tribe Tisamenini )

Harman, 2022: 20, 23. (Notes on culture stock origins)

Bank et al., 2021: 14. (Tribe Obrimini )

Brock & Büscher, 2022: 521.

Hennemann, 2023b: 128.

Acanthoderus, Westwood, 1848 View in CoL : pl. 38: 5 & 6 (in part). Westwood, 1859: 53 (in part).

Hoploclonia, Rehn & Rehn, 1939: 464 View in CoL (in part). (Erroneous synonym) = Ilocano Rehn & Rehn, 1939: 460 View in CoL . (Synonymised by Bank et al., 2021: 14)

Redtenbacher, 1906: 43 (in part).

Bradley & Galil, 1977: 199.

Bragg, 1995: 27.

Zompro, 2004: 208, 312.

Otte & Brock, 2005: 164.

Hennemann et al., 2016: 21.

Bank et al., 2021: 14.

Description. – Very small to medium overall size (body length 18.1-70.0 mm) and stocky to heavy built, usually more or less flattened Obrimini with strongly widened meso- and metapleurae ( ♀ in particular) and a distinctive more or less raised triangular area in the anterior portion of the mesonotum, that is defined by two posteriorly converging carinae that have the anterolateral angles variously modified, from indistinct nodes to large serrate, denticulate or spinose crests. General body shape moderately elongate and sub-uniform ( ♂) to distinctly erratic ( ♀) in diameter; mid portion of metathorax the widest body part with mesothorax often strongly widening towards the posterior ( ♀ in particular); sexual dimorphism strongly developed. Body surface varying from rather smooth over unevenly granular, nodular or tubercular to strongly spinose; meso- and metanotum with a prominent medio-longitudinal carina or bulge. Colour various tones of brown and mostly rather plain, occasionally with indicated longitudinal markings or stripes of various tones of ochre to dark brown or more rarely orange to russet (more often in ♂). Head rectangular, longer than wide, somewhat flattened with vertex just weakly convex; dorsal armature rather weakly developed if compared to other Obrimini and armed either with spines or tubercles or with post-orbital crests or all three of these, the supra-orbital variably shaped and by far the largest element of cephalic armature; coronals rather weakly developed, mostly tubercular and rarely spinose. Antennae short and not reaching ( ♀) to slightly projecting over posterior margin of mesonotum ( ♂); shape generally quite thick, sometimes sub-perlamorph and with antennomeres at best moderately elongated. Scapus slightly compressed dorsoventrally and roundly sub-rectangular in dorsal aspect; pedicellus barrel-shaped and much shorter and narrower; III narrower and about as long as pedicellus; IV much shorter and the following gradually increasing in length with the apical 20 or so joints longest and roughly uniform; consisting of less than 30 joints. Pronotum varying from sub-rectangular or sub-trapeziform to rather broadly transverse; anterior margin usually concave and the transverse median sulcus somewhat displaced towards the posterior and distinctly impressed. Dorsal surface usually with some indication of a raised triangular area; the pre-sulcal area with the anterolateral angles produced into simple or compound tubercles, spines or dentate to serrate crests; these often very prominent and occasionally projecting over anterior margin of pronotum. Mesothorax more or less distinctly widening towards the posterior (more so and often strongly in ♀); mesonotum sub-rectangular and at best 2.7x ( ♀) or 3.2x ( ♂) longer than wide; metanotum notably shorter and also sub-rectangular; both with a distinct medio-longitudinal carina or bulge, which may be discernible in the triangular anterior area of the mesonotum. Lateral margins at best with some nodes or low tubercles and otherwise and occasionally with a variably sized pair of inter-posterior mesonotals. Meso- and metapleurae strongly dilated and expanded, particularly in the posterior supra-coxal portions; mesopleurae with lateral margins varying from tuberculate over denticulate to massively spinose; often the mesopleural spine migrated laterally to such an extend that it is impossible to distinguish from the laterals; the supra-coxal sometimes bifid. Metapleurae even more strongly expanded with lateral margins varying from practically smooth except for the supra-coxal, to strongly dentate or massively spinose; the supra-coxal often forming a very long and strong spine and not rarely bifid. Prosternum with a pair of rounded to slightly elliptical but very prominent sensory area. Meso- and metasternum with a more or less distinct and acute medio-longitudinal carina or keel; mesosternum sometimes tri-carinate with a narrow carinae along each lateral margin; otherwise mostly smooth and at best with a very few small tubercles. Median segment transverse. Abdominal segments transverse in ♀ and sub-quadrate in ♂; II-VI narrowing in ♀, in ♂ roughly uniform in width and diameter. Terga II-IV usually with a variously sized pair of second paired posteriors (more rarely also on V-VII) and occasionally with a variably shaped posterior mesal; II-VII often with a small postero-lateral. Terga VIII and IX usually with a variably shaped posteromedian tubercles, crest or tuberculate, sometimes compound excrescence. Sterna II-VII mostly smooth but occasionally with an indicated medio-longitudinal carina ( ♂ in particular); praeopercular organ on VII of ♀ indistinct and only represented by a shallow median fold or swelling at posterior margin. Terminalia of ♀: Anal segment declining with posterior margin entire and the lateral margins more or less excavated medially. Epiproct not reaching to tip of epiproct with apex entire, either rounded or obtusely angular; dorsal surface obtusely tectate longitudinally and shape sometimes notably convex. Subgenital plate acutely keeled medio-longitudinally with apical portion narrowing and apex acutely pointed; straight in lateral aspect. Cerci small, compressed laterally and hidden underneath anal segment. Terminalia of ♂: Anal segment with a posteromedian excavation; the epiproct fairly large, scale or shield-shaped and usually extending over apex of anal segment. Poculum in ♂ bulgy, angular with posterior margin broad, labiate and weakly excavated to notched medially. Vomer broad with base transverse and with a short and gently straight to gently curved terminal hook. Legs rather short to moderate in length and varying from slender (mostly ♀) to incrassate; all margins of femora carinated and almost always with dentations; the tibiae usually unarmed and only metatibiae with ventral dentations. Tibiae slightly shorter than corresponding femora. Profemora distinctly constricted in basal half with basal flexure prominent. Medioventral carina of femora very indistinct or wanting. In ♂ metafemora often incrassate basally and with a more or less prominent rounded ventro-basal swelling. Area apicalis of tibiae with a small medio-apical tubercle. Tarsi short and no more than half the length of corresponding tibiae; basitarsus about as long as following two joints taken together.

Egg. – Small to medium-sized for Obrimini (length 2.9-4.7 mm), capsule bulgy to ovoid, sub-circular in diameter, slightly higher than wide and at best 1.7x longer than wide; polar-area rounded. Entire surface of capsule and micropylar plate more or less distinctly sculptured and covered with hairy or fringy structures or short setae, in particular along dorsal margin; capsule mostly covered with a variable network of fringy ridges and carinae. Micropylar plate large and> two-thirds the length of capsule; as typical for Obrimini with a dorsal and two posterolateral extensions and shaped like an inverted Y or T. Median line distinct and reaching to polar area. Operculum oval to circular, flattened and often with an elliptic mount or rim of setae in centre. Colour uniformly greyish or variable tones of brown to russet.

Differentiation. – This very distinctive genus is easily separated from all other Philippine members of the tribe Obrimini by the characteristic more or less raised triangular area in the anterior portion of the mesonotum, that is defined by two posteriorly converging carinae that have the anterolateral angles variously modified, from indistinct nodes to large serrate, denticulate or spinose crests. The prominent anterior armature of the pronotum, stocky overall shape and strongly expanded meso- and metapleurae are shared with Pterobrimus , but despite very similar morphology Pterobrimus is endemic to the Fiji Islands and can be differentiated by the presence of small scale-like tegmina. Pterobrimus also has a triangular mesonotal area, but it is just weakly developed. Eggs most closely resemble those of Trachyaretao n in bearing hairy or fringy structures on the operculum and the anterior portion of the capsule, but differ by the much bulgier overall shape, more or less developed net-work of fringy carinae all over the capsule surface, sculpturing of the inner portions of the micropylar plate and more or less pronounced elliptic mount or rim of setae in the centre of the operculum.

Etymology. – Tisamenus (lat.) is the latinized version of the Ancient Greek Tisamenos (Τισαµενός or Tisamenós), a mythological king of Argos and son of Orestes and Hermione, who were the rulers of the Peloponnesus.

Remarks. – Tisamenus was originally described by Stål (1875: 50) to comprise the newly described T. serratorius Stål, 1875 as well as the two species Acanthoderus deplanatus and Acanthoderus draconinus described by Westwood (1848), of which Kirby (1904: 399) selected serratorius as the type-species. Two further species were added by Bolívar (1890) and another by Redtenbacher (1906), all five species originated from the Philippines. In their extensive treatment of Philippine Obriminae Rehn & Rehn (1939: 464) erroneously interpreted Tisamenus as a synonym of Hoploclonia Stål, 1875 , and described nine new Philippine species in what they referred to as Hoploclonia . These authors also provided numerous illustrations of various species as well as a key to the Philippine species. The generic misinterpretation by Rehn & Rehn (1939) was uncovered by Zompro (2004: 206), who re-established Tisamenus as a valid genus and thereby transferred all Philippine species described in Hoploclonia by Rehn & Rehn to Tisamenus . This renders Tisamenus as an endemic of the Philippines, whereas Hoploclonia is endemic to Borneo (Zompro, 2004: 207; Seow-Choen, 2016: 415). Unfortunately, Zompro did not provide a proper differentiation between these two genera and merely stated that “[…] the genera differ considerably ” (Zompro, 2004: 207). Two new species and a list of known species was provided by Lit & Eusebio (2005b) and another new species was described by Lit (2010b) along with an updated key to the species of the Deplanata group of the genus.

Based on morphological characters Rehn & Rehn (1939) sub-divided the Philippine taxa into four generic groups: 1. Draconinus Group ( T.draconinus (Westwood, 1859) , T.hystrix ( Rehn & Rehn, 1939) , T.lachesis ( Rehn & Rehn, 1939)) ; 2. Serratoria Group ( T.serratorius Stål,1875 , T.asper Bolívar, 1890 , T.clotho ( Rehn & Rehn, 1939) , T.atropos ( Rehn & Rehn, 1939)) ; 3. Deplanata Group ( T. deplanata ( Westwood, 1848) , T. armadillo Redtenbacher, 1906 , T. cervicornis Bolívar, 1890 , T. spadix ( Rehn & Rehn, 1939) , T. tagalog ( Rehn & Rehn, 1939) , T. fratercula ( Rehn & Rehn, 1939)) ;

4. Polillo Group ( T. polillo ( Rehn & Rehn, 1939)) .

However, these intrageneric groups were not recovered by the molecular approach presented in Bank et al. (2021). Effectively, external morphology of the insects basically subdivides Tisamenus into only three groups of similar species, this is 1. the Serratorius Group, which comprises the more slender and spinose forms in which the mesothorax is at best slightly widening towards the posterior, 2. the Deplanatus Group, which comprises the stockier and less spinose forms Fig. 2. Physical map of the Philippine Islands , showing the known distribution of the genus Tisamenus Stål, 1875 (Source: Wikipedia Commons. © Eugene Alvin Villar; https://upload.wikimedia.org/wikipedia/commons/6/6f/Ph_physical_map.png)

that have a distinctly trapezoidal mesothorax and mostly lack mesopleural spines except for a single supra-coxal, and 3. The Ranarius Group, which comprises the two species that have a strongly reduced mesonotal triangular area and possess an apical tooth or spine on the outer lateral carina of the scapus.

The study of molecular data by Bank et al. (2021) also included Ilocano hebardi Rehn & Rehn, 1939 , the type-species of the Philippine genus Ilocano , which resulted as deeply imbedded in Tisamenus . Therefore, Ilocano was synonymised with Tisamenus ( Bank et al., 2021: 14) . The second species attributed to Ilocano by its describers, namely Acanthoderus ranarius (Westwood, 1859) , was already transferred to Tisamenus by Zompro (2004: 207). More detailed morphological examination of T. hebardi conducted herein clearly supports the synonymy of Ilocano under Tisamenus and, including the seven species newly described herein, for now the number of known species stands at twenty-four.

As mentioned above, the systematic position of Tisamenus within the Obriminae has varied throughout previous studies. Zompro (2004) combined Tisamenus together with Ilocano , Eubulides and Heterocopus in the tribe Eubulidini , which the author characterised by lacking composite posterior meso- and metanotals. Hennemann et al. (2016) refused Eubulidini and established the tribe Tisamenini to comprise Tisamenus , Ilocano , Hoploclonia and the Fijian Pterobrimus . As some of the characteristics for Tisamenini, Hennemann et al. (2016: 20) mentioned the modified anterior area of the mesonotum, distinct medio-longitudinal keel of the meso- and metasternum, prominent and complex anterior armature of the pronotum and short tarsi of the insect as well as the setae and hairy structures frequently seen in the eggs. Moreover, Hennemann et al. (2016, fig. 97) interpreted Tisamenini as sister to Obrimini + Miroceramiini . Both arrangements based on morphological characters were yet again refused by a phylogenetic study based on molecular data by Bank et al. (2021). Although this latter study provided support for a rather separate and basal position of Tisamenus within Obriminae , it has revealed Tisamenus as being sister to Theramenes , with these to two genera together being sister to the remaining Obriminae (= Obrimini sensu Hennemann et al., 2016 ) with the exception of Hoploclonia , Miroceramia and Pterobrimus .

Distribution (Fig. 2). – Philippines (endemic). Biogeographically, this genus is predominantly restricted to the Greater Luzon Region, which includes the Polillo Islands and Masbate. However, it also has one species on the island of Sibuyan (referred to as a separate biogeographic region), two species in the Greater Negros-Panay Region, one species on the Island of Leyte and one species on Camiguin Island, both of which belong to the Greater Mindanao Region. Therefore, Tisamenus can be referred to as largely Luzonian in its natural geographic range.

Rehn & Rehn (1939: 477, pl. 35: 34) recorded T. deplanatus ( Westwood, 1848) based on a misidentified ♀ from Mindanao (Surigao) and commented “ It is not possible to say whether this specimen came from Surigao, Surigao Province or was picked up at some other point in that province ”. Apart from that the specimen actually is a ♀ of T.cervicornis (Bolívar, 1890) , which is restricted to South Luzon and North Samar, there has not been any other record of the genus Tisamenus from the island of Mindanao. It may also be possible, that the record was misspelled and effectively refers to the small island Siargao southeast of Samar, which from biogeographic aspects would be much more likely. Therefore, this record must be regarded as questionable and a distribution of Tisamenus on Mindanao presumed as unlikely.

Matsumara & Hirayama (1932) recorded a specimen of T.draconinus ( Westwood, 1848) from Kotosho Island southeast of Taiwan, but this single record must most certainly be associated to a meteorological event like northing typhoon that are not uncommon in the Luzon Strait, that separates the Philippines and Taiwan. Thus, Taiwan can be excluded from the potential distributional range of Tisamenus . More details are to be found in the remarks for T. draconinus below.

Species included

1. Tisamenus alviolanus Lit & Eusebio, 2010

Distribution. – Negros.

2. Tisamenus armadillo Redtenbacher, 1906

Distribution. – “ Philippines ”.

3. Tisamenus asper Bolívar, 1890

Distribution. – Central Luzon.

4. Tisamenes cervicornis Bolívar, 1890

= Hoploclonia fratercula Rehn & Rehn, 1939 View in CoL n. syn.

Distribution. – South Luzon, North Samar & Bohol.

5. Tisamenus charestae Hennemann & Le Tirant n. sp.

Distribution. – North Luzon.

6. Tisamenus clotho ( Rehn & Rehn, 1939)

= Hoploclonia atropos Rehn & Rehn, 1939 View in CoL n. syn.

Distribution. – Polillo & Luzon.

7. Tisamenus deplanatus ( Westwood, 1848)

Distribution. – North Luzon.

8. Tisamenus draconinus ( Westwood, 1848)

Distribution. – East Luzon, Polillo & Leyte.

9. Tisamenus hebardi ( Rehn & Rehn, 1939)

Distribution. – North Luzon.

10. Tisamenus heitzmanni n. sp.

Distribution. – Cebu.

11. Tisamenus hystrix ( Rehn & Rehn, 1939)

Distribution. – Sibuyan.

12. Tisamenus irenoliti n. sp.

Distribution. – Marinduque.

13. Tisamenus kalahani Lit & Eusebio, 2005

Distribution. – North Luzon.

14. Tisamenus lachesis ( Rehn & Rehn, 1939)

Distribution. – Polillo, Luzon & North Samar.