Chimarra triangularis occidentalis Gibon, 1985

Blahnik, Roger & Andersen, Trond, 2022, New species of the genus Chimarra Stephens from Africa (Trichoptera, Philopotamidae) and characterization of the African groups and subgroups of the genus, ZooKeys 1111, pp. 43-198 : 43

publication ID

publication LSID

persistent identifier

treatment provided by

ZooKeys by Pensoft

scientific name

Chimarra triangularis occidentalis Gibon, 1985


Chimarra triangularis occidentalis Gibon, 1985

Fig. 22A-G View Figure 22

Chimarra triangularis occidentalis Gibon, 1985: 27, figs 11-12.

Marterial examined.

Ghana - Western Reg. ● 1♂; Ankasa Game Production Reserve; 5°15'N, 2°37'W; 11 Dec. 1993; T Andersen & J Kjærandsen leg.; light trap; UMSP ● 12♂♂9♀♀; same collection data as for preceding except 5-9 Dec. 1993; ZMBN ● 1♀; same collection data as for preceding; UMSP ● 3♂♂; same collection data as for preceding except 31 Apr. 1993; J Kjærandsen leg.; ZMBN ● 2♂♂; same collection data as for preceding except 6-12 Dec. 1993; Malaise trap; ZMBN.


Characters, in combination, that confirm the identification and can be used to distinguish C. triangularis occidentalis from the nominate subspecies and other species in the subgroup include: the general shape of inferior appendages, shape of segment IX and ventral process, relatively short tergum X and length of sensilla-bearing process, and presence of large apical phallic spine.

Chimarra triangularis occidentalis was considered a subspecies of C. triangularis Kimmins when described by Gibon, probably because of the overall similarity between the two forms in the shape of the inferior appendages, length of tergum X, and similarity of its phallic armature. Kimmins described C. triangularis as having two sets of paired inclusions in the phallus and two single, unpaired inclusions. One of the sets of paired inclusions and one of the unpaired inclusions seem to be elements of the phallotremal sclerite complex, including a central rod and ring structure and paired lateral sclerites. The other inclusions include a set of small, paired spines, common in members of the Chimarrha kenyana subgroup, and an unpaired apical spine-like sclerite. Gibon described the subspecies based mainly on differences in the phallic armature, including a larger unpaired spine than that found in the nominate form. We have used this as the basis for identifying the form illustrated here as C. triangularis occidentalis (Fig. 22A-G View Figure 22 ), in addition to its relatively proximate geographic location. The nominotypical form was described from Ethiopia, on the other side of the African continent. The apical spine is somewhat unusual, very lightly sclerotized, and appearing somewhat feathered or striated. Its apical part appears wider in lateral view than in dorsal view, suggesting that it is somewhat blade-like. We are uncertain about the species or varietal status of this form, as distinct from the form described by Kimmins.

Chimarra triangularis occidentalis is most diagnostically recognized by the overall shape of its inferior appendages, with its short tergum X and very short basal sensilla-bearing process. Among species treated here it is probably most similar in these regards to C. pedaliotus sp. nov., which is easily diagnosed by the very enlarged and compressed ventral apex of its phallobase.


Adult. Overall color (in alcohol) pale yellowish brown. Head relatively elongate (length of postocular parietal sclerite nearly diameter of eye). Palps relatively short, maxillary palp with 1st segment very short (length subequal to width), 2nd segment short (~ 3 × 1st), apex with small cluster of stiff setae, 3rd segment relatively short (slightly longer than 2nd), 4th segment short (shorter than 2nd), 5th segment short (subequal to 2nd). Forewing length: male, 3.8-4.5 mm; female, 4.7-5.2 mm. Fore- and hind wings with forks I, II, III, and V present. Forewing with R1 somewhat sinuous, stem of Rs inflected at approximately midlength, with distinct node at inflection, extending into cell below, basal fork of discoidal cell enlarged, fork asymmetric, length of cell ~ 2 × width, forks I and II slightly subsessile, r crossvein diagonal, intersecting discoidal cell at past midlength, just before fork I, m crossvein proximal to s and r-m crossveins, s pigmented (like wing), r-m and m crossveins hyaline and very faint, 2A with crossvein (apparently forked apically to 1A and 3A). Hind wing with R1 narrowly parallel to subcosta, forks I and II subsessile, fork III relatively terminal. Foreleg with apical tibial spur short; male with foretarsi modified, claws enlarged, outer claw twisted and asymmetric.

Male genitalia. Segment VIII moderately elongate, sternum and tergum subequal in length. Segment IX, in lateral view, elongate, anterior margin greatly, subangularly produced in ventral ¼, dorsolaterally with short rounded apodeme, margin strongly concave between; tergum, in dorsal view, continuous between apodemes, forming concave excavation; posterior margin weakly produced below preanal appendages, extending more or less linearly to ventral process; ventral process prominent, posteriorly projecting, length greater than width at base, apex rounded. Segment IX, in dorsal or ventral views, with anteroventral margin deeply concave mesally. Lateral lobes of tergum X moderate in length, rounded apically, each with moderately elongate, posteriorly projecting, digitate, sensilla-bearing process on dorsal margin at approximately midlength; mesal lobe of tergum X membranous, somewhat shorter than the lateral lobes. Preanal appendages small, rounded, constricted basally. Inferior appendage, in lateral view, moderately elongate, narrow, nearly uniform in width, dorsally flexed near base, apex incurved and narrowed, in dorsal/caudal views, forming short, subtruncate, weakly bifid, projection; appendage, in dorsal or ventral views, strongly and uniformly curved, with short, rounded, setose, basomesal projection. Phallic apparatus with phallobase moderately elongate, tubular, with usual basodorsal expansion, dorsal margin somewhat projecting, but only weakly sclerotized, apicoventral margin slightly projecting, extending nearly straight; endotheca apparently without minute spines, but with two symmetrically positioned spines and an additional large, unpaired, lightly sclerotized, mesal spine, which is somewhat irregular, wider in lateral than in dorsal view; phallotremal sclerite complex composed of moderately elongate rod and ring structure, with narrow, paired, dorsolateral sclerites.


Ghana, Ivory Coast.














Chimarra triangularis occidentalis Gibon, 1985

Blahnik, Roger & Andersen, Trond 2022

Chimarra triangularis occidentalis

Gibon 1985