Neoperla arambourgana Navás, 1936

Zwick, Peter & Zwick, Andreas, 2023, Revision of the African Neoperla Needham, 1905 (Plecoptera: Perlidae: Perlinae) based on morphological and molecular data, Zootaxa 5316 (1), pp. 1-194 : 169-171

80. Neoperla arambourgana Navás, 1936

( Figs. 459–467)

Neoperla arambourgana Navás, 1936 : Mém. Mus. Nat. Hist. Nat., N.S. 4: 124.

Neoperla sp. , Hynes (1952): 98, Fig. 4A (♀ from Mount Elgon , Kenya).

Type material studied. Lectotype J, Republic of Kenya Suam fishing hut Mt ELGON [1.023, 34.53] VERST EST 2400 m [print, white paper] \ Neoperla arambourgana ♁ Nav. det. Navás S. J. [blue paper, in Navás’ hand] \ Tipo [red paper, handwritten] \ Muséum de Paris Mission de L’Omo C.Arambourg P.-A.Chappuis & R.Jeannel 1932–33 [print, blue paper] ( MNHN; NEOP 270, Figs 459, 460; pinned, genitalia in microvial on pin). The lectotype is designated here to ensure stability of nomenclature. In the description, Navás mentions several samples but the only avalable ♀ paralectotype is misassociated: it is actually N. kalengonis n. sp. We know of no additional presently unavailable paralectotypes.

Additional material studied: Democratic Republic of the Congo. 1♀: Coll.Mus.Congo Kwango: Popokabaka [-5.691, 16.5852] II.1952 L. Pierquin ( MRAC, NEOP271 , slide Z19.49). 1♁, Musée du Congo Sankuru [-3.51342, 23.59863] Lodja VII-1928 J. Ghesquière \ R. det. 1943 P \ Neoperla Haugi Nav. P. Navás S.J. det.; 1♁, Sankuru [~ -2.844, 23.384] Prov. Lusambo, 1925, J. Ghesquiere ( Tervuren ). 1♁, Musée du Congo Niembo-Kalenbe Lembe [- 1.02524, 28.9383] VII-1918 R. Mayné [Z19.48]; 1♁, Coll. Mus. Congo Elisabethville (à la lumière) XII-1956 Ch. Seydel [Z19.44]; 1♁, Musée du Congo Rutshuru V-1937 J. Ghesquière [Z19.43]; 1♁, Musée do Congo Leverville - IX-1920 P. Vanderijst [Z19.47]; 2♁, Musée du Congo Rutshuru V-1937 J. Ghesquière MRAC ( Z19.38 , NEOP269 ) (all MRAC, Tervuren). 1♀, riv. Eulya- Bilombo [-5.26, 26.81] route Kamituga, en vol 23.8.50 G. Marlier (slide Z74/11). 1♀: Urwald-Ukaika [0.48, 29.46] Dez. '10, Grauer \ Neoperla \ africana Klapálek [print] ( NEOP274 ); 1♀, Urwald Mawambi [1.05, 28.58] 1910. Grauer \ africana Klapálek [print] ( NEOP273 ) (both NHMW, genitalia in microvials on pin). 2 ♀: B.Congo, 39 mi E of Masi Manimba [- 4.77S, 17.90E], 5.8.57 Ross & Lorenzen ( CASENT 8413105 , slide Z18.58). 1♁ ANG. 3330.12. Dundo XI.53 (L) (old penis slide, SMNS). 1♁ ( CASENT 8413060 , Z18.34), 20 ♀ ( CASENT 8413104 ): B. Congo, 39 km S of Walikale [- 1.47S, 28.07E], 700m, XII-25-57 E.S.Ross & R.E.Leech ( CAS & SMNS). 2♀, B.Congo, 23 mi E of Kama [3.52S, 27.12E], 16.8.57, Ross & Leech ( CASENT 8413100 ; slide Z18.59; and ( NEOP272 , SMNS ex CAS)); 1♀, 1♁: I.R.S.A.C Irange [-1°54’, 28°27’: Viets & B̂ttger (1974), 800m, 16.9.57. Ross & Leech ( CASENT 8413101 ) Slide 18.60. Republic of Kenya: 1♀: Brit. E. Africa, S. foot & slopes of Mt. Elgon 5100–5800 ft \ June 8–13 1911 S.A. Neave ( BMNH; fide Hynes, 1952a: fig. 4A, as N. spio ).

Habitus. WL 11.3–12.3mm, 12.0mm in the lectotype. Colour ochre, an ocellar spot and a vague line along occipital suture are brownish. Flagellum, tibiae and distal part of cercus infuscate. Male hind tibia a little widened.

Male ( Figs. 459–462). A transverse medially concave sclerite is located caudally from a narrow pale line near midlength of T7. A wide sclerite band extends back from this sclerite, and down into the intersegmental fold.A broad band on T8 supports a wide hook with triangular to pointed apex, the anterior face with some SB. The hook is high and curves towards T7 without touching it. A narrow band extends from the caudal face of the hook to the median gap in the divided antecosta T9. The lateral pilose humps on T9 are unmodified but from the front end of the median furrow between them rises a low parabolic process behind which the median slightly sclerotised furrow continues, to near the epiproct. The HT10 process is short and hardly curved, tip blunt. The tongue-shaped mediobasal callus partly conceals the Y-shaped epiproct. Sternites are unmodified.

Penis ( Figs. 461–462) as for the complex. The everted endophallus is straight and narrows distally. The teeth along the sides of the endophallus are fairly small. Near the base there are no spines in the middle, distally the entire dorsal side bears many unordered small spines that grow distally finer but are absent from the end section.

Female ( Figs. 463–465, 467). Caudal edge of S8 with two soft sharp points between which a parallel-sided notch leads forward to a crescent-shaped brown sclerite without crests. Vagina unmodified, the SSt is slender and forms approximately three rings of uniform width. The basal region which bears scales only on the convex side is short, distally scales completely cover the SSt.

Egg ( Fig. 466). Ovoid, elongate, 371*178µm. Collar short, with only one ring of cells. Anchor cavity shallow, anchor mushroom-shaped. Numerous almost straight, slightly levogyrous striae extend far onto the parabolic operculum which bears some cells but the very top is punctate. The costae are flat and wide, the sulci are narrow, with two rows of micropunctures and the micropyles in elongate-oval widenings.

DNA ( Figs. 491–492, 497). A total of six specimens from the D. R. Congo and Kenya were sequenced, representing the known geographic distribution of this species and providing very strong support (98.3/100/100) for the monophyly of the species. The species is maximally supported (100/100/100) as sister to N. dundoana n. sp.. Both sexes are represented .

Variation. The molecular data revealed that S8 of females has the characteristic shape ( Figs. 363–365) only in specimens from Mt. Kenya and from mountains along the Great Rift Valley. In females from further west in the Congo area the sclerite on S8 has a less regular caudal notch and is in contact with the caudal segment edge ( Fig. 467). Such specimens resemble N. dundoana n. sp. ( Fig. 469) but can be distinguished by their eggs with levogyrous or straight striae, respectively ( Fig. 466 vs. Fig. 468).

Notes. Navás (1936) described N. arambourgana from Mt. Elgon as “similis leroianae Klap. Major”. The small median process on T9 appears to be serially homologous (homonomous) with the hook on T8. Homonomous tergal structures previously described in Plecoptera were considered anomalies ( Aubert 1956b, Lillehammer 1974, Zwick 1976b) but this one is not. The forward shift of the vaginal sclerite away from the caudal edge of S8 is derived.