Chimarra akana Gibbs, 1973

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

Chimarra akana Gibbs, 1973

Fig. 15A-E

Chimarra akana Gibbs, 1973: 366-367, figs 14-16.

Chimarra akana Gibbs: Marlier 1980: 62 (as possible synonym of C. kenyana Ulmer); Gibon 1985: 25, figs 7, 12 (distribution: Ivory Coast).

Material examined.

Ghana - Eastern Reg. ● 4♂♂ 3♀♀; Kibi, Subri stream; 6°10'N, 0°33'W; 5 Nov. 1993; J Kjærandsen leg. ; light trap; ZMBN. - Volta Reg. ● 1♂; Kute, River Menu ; 7°22'N, 0°36'E; 11 Dec. 1990; JS Amakye leg. ; light trap; ZMBN ● 1♂; Wli, Agumatsa waterfall, station # 2A; 7°07'29"N, 0°35'31"E; 8-11 Mar. 1993; JS Amakye & J Kjærandsen leg. ; Malaise trap; ZMBN ● 15♂♂ 11♀♀; same collection data as for preceding except station # 3; 17 Nov. 1993; J Kjærandsen leg. ; light trap; ZMBN ● 1♂; same collection data as for preceding except station # 6; 11 Mar. 1993; JS Amakye & J Kjærandsen leg. ; ZMBN ● 1♂; same collection data as for preceding except station # 10; 19 Nov. 1993; J Kjærandsen leg. ; UMSP ● 10♂♂ 2♀♀; same collection data as for preceding except station # 15; 5 Dec. 1993 ; ZMBN ● 1♀; same collection data as for preceding except station # 19; 9 Dec. 1993 ; ZMBN. - Western Reg. ● 1♂ 1♀; Ankasa Game Production Reserve ; 5°15'N, 2°37'W; 6-12 Dec. 1993; T Andersen & J Kjærandsen leg. ; Malaise trap; ZMBN ● 1♂; same collection data as for preceding except 11 Mar. 1993; J Kjærandsen leg. ; light trap; ZMBN ● 10♂♂ 3♀♀; same collection data as for preceding except 5-9 Dec. 1993; T Andersen & J Kjærandsen leg. ; ZMBN ● 1♀; same collection data as for preceding except 19 Dec. 1993 ; UMSP.

Diagnosis.

Characters, in combination, that confirm the identification and can be used to distinguish C. akana from other species in the subgroup include: the general shape and length of tergum X and position and length of digitate dorsal process; overall shape and length of inferior appendage and shape of apex in lateral view (orientation of appendage is slightly more bowed outward in specimen from Ghana); general shape of segment IX and length and shape of ventral process; details of phallus, especially the pair of curved ventral spines and upturned dorsal apex of phallobase.

The form illustrated here (Fig. 15A-E ) closely matches the illustration provided by Gibon (1985: figs 7-8). As compared to the illustration of the species provided by Gibbs (1973: fig.16), the apex of the inferior appendage appears to be more sinuate. This is probably a matter of the orientation of the structure when illustrated (more or less caudal in the specimen illustrated by Gibon (1985: fig. 8), and more ventral in the specimen illustrated by Gibbs (1973: fig.16). For now, we accept Gibon’s illustration as representing this species. Marlier (1980), who synonymized C. wittei Jacquemart with C. kenyana Ulmer, also suggested that C. akana may be synonym of this species. Both of these species would have name priority over C. akana . Unfortunately, the illustrations provided for the species do not provide enough details to make an informed conclusion. The issue, including the synonymy made by Marlier, should be addressed in a future revision of the subgroup.

Diagnostic features of C. akana include, in particular, the shape of the inferior appendages which are relatively narrow and strongly bowed, with the apex somewhat narrowed and upturned, as viewed caudally, with the relatively elongate dorsal sensilla-bearing lobes of tergum X and the phallic armature, which includes a pair of ventrally curved spines near the base of the endotheca and also a pair of very narrow spines apically, in addition to the phallotremal sclerite complex. The dorsal margin of the phallobase is also somewhat produced and upturned apically, but only weakly sclerotized, so the feature may not always be evident. As in all species of the Chimarrha kenyana subgroup, the shape of the genital capsule and ventral process of segment IX are also important considerations in making species determinations, even if these features are not absolutely consistent. Compared to other species in the subgroup, C. akana has a relatively short segment IX, with the anteroventral margin produced and a narrow, posteriorly projecting ventral process.

Redescription.

Adult. Overall color (in alcohol) nearly uniformly yellowish brown. Head relatively short (postocular parietal sclerite <1/2 diameter of eye). Palps moderately elongate; maxillary palp with 1st segment very short (slightly longer than wide), 2nd segment short (~ 2 × 1st), apex with small cluster of stiff setae, 3rd segment elongate (~ 1½ × 2nd), 4th segment short (slightly shorter than 2nd), 5th segment elongate (subequal to 3rd). Forewing length: male, 4.5-5.2 mm; female, 4.8-5.8 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, 2A with crossvein (apparently forked apically to 1A and 3A). Hind wing with R1 narrowly parallel to subcosta, forks I and II subsessile. Foreleg with apical tibial spur short; male with foretarsi modified, claws enlarged, outer claw twisted and asymmetrical.

Male genitalia. Segment VIII relatively short, sternum and tergum subequal in length. Segment IX, in lateral view, relatively short, anterior margin distinctly produced and rounded in ventral ¼, dorsolaterally with broad, weakly developed, apodeme; tergum continuous dorsally, forming concave excavation between lateral apodemes; posterior margin very weakly produced below preanal appendage, widening ventrally to level of inferior appendage; ventral margin rounded between anteroventral production and inferior appendage, ventral process midway between, short, narrow, acute apically. Segment IX, in dorsal or ventral views, with anteroventral margin deeply concave mesally. Lateral lobes of tergum X relatively elongate, subtruncately rounded apically, with moderately elongate, digitate, sensilla-bearing process from dorsal margin in basal half; mesal lobe of tergum X elongate, membranous, somewhat shorter than lateral lobes. Preanal appendages small, rounded, constricted basally. Inferior appendage, in lateral view, relatively elongate, narrow, strongly dorsally flexed near base, apex somewhat narrowed, rounded as viewed laterally, with sinuous dorsal inflection as viewed caudally; appendage, in caudal view, very strongly mesally curved. Phallic apparatus with phallobase tubular, with usual basodorsal expansion, apicoventral margin weakly projecting, dorsal margin somewhat extended, weakly sclerotized, with apex slightly upturned; endotheca with pair of prominent, symmetrical, ventrally curved spines basoventrally, and pair of very narrow, needle-like spines apically; phallotremal sclerite complex composed of moderately elongate rod and ring structure, with relatively elongate, paired apicolateral sclerites, each terminating in a distinct short spine.

Distribution.

Ghana, Ivory Coast.

Figures

Figure 15. Chimarra akana Gibbs, ♂ genitalia A lateral B dorsal, segments IX and X C inferior appendage, caudal D phallus, lateral E phallus apex, ventral.