Cestromoecha, Brunner von Wattenwyl, 1878, 1893

Hemp, Claudia & Massa, Bruno, 2021, Biogeographical and evolutionary aspects of a Guineo-Congolian bushcricket tribe: Revision of the genera Cestromoecha Karsch, 1893 and Poreuomena Brunner von Wattenwyl, 1878, with the description of new species (Orthoptera, Tettigoniidae, Phaneropterinae), Deutsche Entomologische Zeitschrift 68 (1), pp. 45-79 : 45

Tribe Poreuomenini Brunner von Wattenwyl, 1878

Iconography.

The name Poreuomena is probably derived from the Greek verb Πορεύω meaning "bringing something into a definite direction". The name Cestromoecha is probably derived from Κέστρον, an instrument used in pyrography (drawing by means of heat), pointed on one side and rounded on the other. The same name was used by the Macedonians to indicate a particular type of arrow; the word indicates something that has the form of κέστρον (κέστρον μοι έχειν).

Remarks on the tribe Poreuomenini .

Brunner von Wattenwyl (1878) erected the group Poreuomenae and the genus on the single species Poreuomena africana from Gabon, the only species known in this group at that time. Brunner von Wattenwyl (1878) noted that the new genus is similar in habitus to the genus Phaneroptera . Regarding differences to Phaneroptera both sides of the tympanal organs are closed in Poreuomena (not true for all newly-described species though, see below) while they are open in Phaneroptera . Furthermore, the fore tibiae are smooth without any furrow at their dorsal sides and completely unarmed. These characters differentiate the Poreuomenini from Phaneropterini and place them near to the Holochlorini (formerly divided into Holochlorae and Psyrae). Since Poreuomena was erected on the species Poreuomena africana generic characters were the 10th abdominal tergite of the males being extended in two lobes and the Rs vein branching off near the base of the tegmen.

Karsch (1890) described Poreuomena tenuipes but erected a few years later his own genus on this species ( Karsch 1896). The differentiating character for the two genera as given by Karsch (1896) was a bilobed 10th male tergite in Poreuomena and an undifferentiated 10th tergite in Cestromoecha . Further Karsch noted that the first side vein of the radius (Rs) typically branches off near the base in Poreuomena but more in or behind the middle in Cestromoecha (Figs 1 , 2 ). Comparing all species we found that a further typical character of Poreuomena is flaps on both tegmina - both with stridulatory files on the underside (Figs 6-8 ). A flap and very likely convergently-evolved similar structure is only found in the East African endemic Ectomoptera Ragge, 1980 that has, however, a well-developed mirror on the right tegmen, while in Poreuomena a mirror is lacking completely. On the right tegmen only a reduced stridulatory file is found in Ectomoptera (for a review of stridulatory files on the right tegmen of Ensifera see Leroy 1970 or Chamorro-Rengifo et al. 2014). Table 1 shows a compilation of characters for species of the two genera Poreuomena and Cestromoecha with respective taxonomic changes.

Referring to the type species of Poreuomena , P. africana , and Cestromoecha , C. tenuipes , several species are currently misplaced and are here transferred to their respective genus on grounds of generic characters given above and below. A very obvious distinguishing character on generic level is the presence ( Poreuomena africana ) or absence ( Cestromoecha tenuipes ) of a mirror on the right side of the tegmen (Figs 3-5 ) - as well as the well-developed flaps with the stridulatory files on the underside in Poreuomena (Figs 6-8 ). Cestromoecha either has, at most, a small bulge on the left tegmen and a separate flap with a stridulatory file on the underside on the right wing but a well-developed mirror.

Karsch (1896) noted that he could not decide whether Poreuomena crassipes , described by him on a single female, also belonged to the new genus Cestromoecha or not since the male was unknown. Ragge (1968) in his index-catalogue of African Phaneropterinae listed the latter species under Cestromoecha without giving reasons for this change. Massa (2013) described the male of C. crassipes leaving it with Cestromoecha , although having a bilobed 10th tergite and tegminal flaps typical for Poreuomena . Poreuomena magnicerca transferred by us from Cestromoecha , has typical tegminal flaps, a Rs branching off from the radius near the base of the tegmen, however, for Poreuomena , with an untypical, undifferentiated and thus not bilobed 10th abdominal tergite. All other known Poreuomena species, including the here newly-described species have tegminal flaps on both tegmina, except for P. matthaei sp. nov. with a bulge at the right base of the tegmen. A flap is here defined as elongated and narrow, mostly pointed structure at the base of the tegmina, while a bulge is a broad and not pointed structure. Further, Poreuomena species have a Rs branching off from the radius near the base and a 10th abdominal tergite derived from a bilobed basic structure (elongated bulges or with short or long, straight or downcurved lateral processes). Two species remain in Cestromoecha , C. tenuipes (syn. C. mundamensis ) and C. longicerca , both having mirrors on the right side of the tegmen and no tegminal flaps (Figs 10 , 12 , 17 ).

Figures

Figures 1 - 5. Venation of Poreuomenini. Arrows point at Rs branching of from the radius 1. Rs branching off after the middle in Cestromoecha tenuipes. 2. Rs branching off basally, for example, in Poreuomena africana. 3 - 5. Mirror area of Cestromoecha tenuipes lacking the flaps on both tegmina bases, but with a well-developed mirror on the right tegmen (arrows). 5. Mirror area of Cestromoecha tenuipes from the underside with a well-developed stridulatory file, typical for all Poreuomenini.

Figures 6 - 8. Tegminal flaps at the bases of the tegmina, here in Poreuomena tshuapa sp. nov., a generic character for the genus Poreuomena.

Figures 9 - 15. Morphological details of male Cestromoecha longicerca. Habitus (9). Stridulatory area with mirror on right tegmen (10), stridulatory file on the underside of the left tegmen (11), close-up of mirror (12), abdominal apex in lateral view (13), rear view (14) and subgenital plate (15).

Figures 16 - 21. Morphological details of male Cestromoecha tenuipes. Habitus (16), stridulatory area (17), stridulatory file on the underside of the left tegmen (18), abdominal apex in lateral (19) and dorsal view (20) and subgenital plate (21).