Neoperla occulta, Zwick & Zwick, 2023

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 : 81-83

33. Neoperla occulta n. sp.

( Figs. 179–180 , 186–187 )

Neoperla africana — Zwick 1973b: 382, figs 1,2; partim; not africana Klapálek, 1909 .

Type material. Holotype J, Central African Republic, 25.10.2008 18h-5h 03°05’20.6” N 16°10’43.0” E, bord du fleuve Sangha ( NEOP061 ) , Paratypes, 2♁, 3♀ Central African Republic , near Bayanga, 2°28’49.5”N 16°12’55.9”E, 22.11.– 1.12.2010 ( NEOP062 , NEOP058 , NEOP059 , NEOP060 , NEOP063 ; 25.10.– 1.12.2010, all preserved dry, pinned slides; SMNS). 1♀ paratype, Republic of Liberia, 8 mi NW Belefuanai , S fork S.Paul R., 11.8.66, Ross & Lorenzen ( CASENT 8413023 ) .

Additional material studied. Republic of Cameroon: 2♁, 1♀ Cameroun , 14 mi NE Bétaré-Oya [5.59N, 14.08E], 930m, 3.X.66 Ross & Lorenzen ( CASENT 8413021 ) . Central African Republic, near Bayanga : 4♁, 14- XI-2010, nuit, UV, 18h30-3h30, Molongo, village, bords fleuve Sangha 02°27’11.6”N 16°04’58.7”E 343 m; 1♁, 02-XII-2010, nuit, UV, sol, clairière, proche camp lac 1 02°28’42.1”N 16°13’13.9”E 405 m ( SMNS) . Democratic Republic of the Congo: 1♀, Bokuma [- 0.666S, 21.016E], 2.4.41, D.Hulstaert ; 1♀, Musée du Congo Bassin Lukuga IV-VII-1934 De Saeger; 1♀, Musée du Congo Mongupa [2.41, 20.77] Lisala 22-IX-1922 A. Collart ; 1♀: Likimi [2.777N, 20.765E], IX.1929, A. Collart ( MRAC) . Republic of Ghana, leg. Endrödy-Younga: 4♁, Banda-Nkwanta , N 8.22, W 2.09, 122 m, 5.–29.9-1965, light trap, on savanna; 2 ♁, 1♀, Bui Camp [8.38N, - 2.37W], 27.10.– 1.12.1965 ( HNHM & SMNS, genitalia slides) . Republic of Liberia, 38 mostly immature ♀, 1♀ slide>Z23.01, 8 mi NW Belefuanai , S fork S. Paul R., 11.8.66, Ross & Lorenzen ( CASENT 8413023 ) .

Habitus. Male WL 8.7–10.7mm, female 10.5–11.7mm. A light ochre species with a black spot across the ocelli. Tips of antenna and cercus dark, femora light, basal 4/5th of tibia and entire tarsus dark, male hind tibia widened slightly.

Male ( Figs. 179–180 ). Similar to N. pilulifera n. sp., except process on T7 less sharply pointed and tip of HT10 shorter and straight. No external spines on penis. Membranous zone between tube and endophallus with only few distally pointing spines in a sparse regular row, bare section of endophallus ~1/4 of total length. About 10 slender sharp-tipped hooks stand dorsally and laterally on the membrane at the penis tip ( Figs. 179–180 ).

Female ( Fig. 186 ). S8 unmodified, no sclerites, no pigmentation. Vagina resembling N. pilulifera n. sp., but the spermathecal stalk seems to be more slender. Egg ( Fig. 187 ). Body (without collar) ~1.36 times longer than wide, poles rounded, both of the same width. Average size is 304*209µm, including the 19µm long collar which projects from the anchor pole as a narrow tube corresponding to only 12% of egg width. Rim slightly flared, no or vestigial cells. The stem of the mushroom-shaped anchor is thin, cap of normal shape.

Notes. Males of N. pilulifera n. sp. and N. occulta n. sp. are easily distinguished by their penes. In contrast, separation of females is difficult, even when eggs are available. Eggs of N. occulta n. sp. look more slender and parallel but distinction from N. pilulifera n. sp. is best based on the narrowness of the N. occulta n. sp. collar of only 12% of maximum egg width. The distinction was validated by biometry of eggs from specimens identified by DNA.

DNA ( Figs. 492 , 494). A total of six specimens from the Central African Republic were sequenced, representing only a small part of the distribution of this species. All sequences are only the COX1 DNA barcode fragment, including from the male holotype. The sequences are identical and support near maximally (99.9/100/100) the monophyly of this species, which is genetically very distinct (i.e., long branch). This species is very strongly supported (92.5/97/98) as sister to N. nichollsi n. sp.. Both sexes are well represented .

Etymology. For a long time, there seemed to be only one kind of female (the working name sp. 11 was used on many labels) for two very distinct males, N. pilulifera n. sp. and N. occulta n. sp.. Females of N. occulta n. sp. remained hidden (Lat. adjective occultus) until revealed by DNA sequencing.

Figures

FIGURE 492. Simplified overview of codon-model maximum likelihood phylogram based on 356 mitochondrial genome and COX1 DNA barcode sequences (all-NT). Terminal labels include information on the species only. Clades of particular interest highlighted with colours that correspond to the clades in other trees. The full tree is shown in Figs 493-498.

FIGURES 177–180. Neoperla aethiopica n. sp. and N. occulta n. sp.. N. aethiopica: 177, penis of holotype (NEOP074); 178, enlarged distal section of the endophallus of the paratype. N. occulta: 179, distal half of penis with everted endophallus (Bayanga LP1); 180, distal part of contracted penis (Bayanga PJ, NEOP058). The curved line connects corresponding structures. Scales are 100µm. bbs, bare basal stretch; bl, basolateral, dd, dorsodistal, dl, dorsolateral spine groups.

FIGURES 181–192. ♀♀ of the Neoperla pilulifera-complex. N. pilulifera n. sp.: 181, genital situs, ♀ from Ghana, Ankasa Reservation; 182, egg of same, arrows show micropyles; 183, 184, collar and micropyle of ♀ from Gabun, Belinga; 185, “teleskoping” collar of ♀ from Schouteden, Koteh / Belinga. N. occulta n. sp.: 186, 187, genital situs and egg, Central African Republic, Bayanga. N. nichollsi n. sp., 188–192: 188, 189, genital situs and egg (Liberia, 8 mi NW Belefuanai, S fork S.Paul R., 11.8.66, Ross & Lorenzen diagrammatic, from photographs) (NEOP057); 190–192 are anchor pole regions of an intact and of 2 teratological eggs, all from the same ♀. In 186–188 ♀ situs and eggs to the same scales, respectively. The scale in 181 is 100µm, others figures as indicated, or not to scale. a, anchor; od, oviduct; rd, receptacular duct; sa, spermatheca; SSt, spermathecal stalk.