Curtonotum ndoki Kirk-Spriggs, 2023

Kirk-Spriggs, Ashley H., 2023, A new species of the Curtonotum platyphallum species-group (Diptera: Curtonotidae) from Nouabalé-Ndoki National Park, Republic of Congo, Zootaxa 5227 (1), pp. 137-142 : 138-141

Curtonotum ndoki Kirk-Spriggs , sp. n.

Figs 1–7 .

Etymology. The specific epithet ndoki is a noun in apposition, named after the type locality Nouabalé-Ndoki National Park, Republic of Congo.

Description: J (based on unique field-pinned holotype).

As described for C. marriott Kirk-Spriggs, 2013 (see Kirk-Spriggs & Wiegmann 2013: 67), differing in the following respects:

Measurements: Overall length unknown (abdomen removed for dissection); length of head and thorax combined 3.8 mm; length of thorax and scutellum combined 3.6 mm; wing length 5.4 mm.

Head ( Figs 1, 3 ). Eye height/length ratio: 14: 8; frons ( Fig. 3 ) length/width ratio: 9: 12; arista with 11 dorsal branches and 4 ventral branches; face uniformly grey dusted, without silver fascia between eye margin and ptilinal fissure, edge adjacent to ptilinal fissure concolourous with face; 17 fine setae bordering genal groove; eye height/ genal height ratio: 14: 4.

Thorax ( Figs 1, 2 ). Postpronotum with 22 fine setulae; anepisternum with ca 40 fine setulae; dorsal katepisternal setae ca ½ length of ventral, with 26 short, fine setulae.

Scutellum ( Fig. 2 ). Concolourous with median part of scutum, apical marginal setae slightly shorter than lateral marginal setae.

Legs. Uniformly pale yellow; fore coxa with 22 brown setulae; fore tibia with ctenidium of 16 short, weaklydeveloped spinules.

Wing ( Fig. 4 ). Membrane slightly darker in anterior ¼, bordering both sides of vein R 2+3 and over dm–m crossvein; dm–m crossvein with acute angle.

Abdomen. Sternite 6 ( Fig. 5 ) apically expanded, with sides evenly rounded, with relatively deep, wide, V-shaped apical excision, clothed in short black irregular brown setulae, those at apical margin longer and more prominent.

Terminalia ( Figs 5–7 ). Hypandrium ( Fig. 6 , hypd) with 2 setulae proximal to postgonite (obscured by epandrium on Fig. 6 ); postgonite (pgt); epandrium (epand); cercus (cerc); surstylus (sur) as illustrated in Fig. 6 ; phallus as illustrated in Fig. 7 , phapod, basph, distph); ejaculatory apodeme missing from holotype; basiphallus ( Fig. 7 , basph) narrow and regular in basal ¼, then slightly narrowed, with moderately sclerotised spur-like extension of left side clearly visible through cuticle, inner lateral margin developed into convex, prominent acute spur-like projection ( Fig. 7 ); distiphallus ( Fig. 7 , distph) short, subdivided into apically expanded, forked basoventral process (bv proc) with two finger-like processes.

♀ Unknown.

Differential diagnosis. Based on wing venation (especially the similar shape of the dm–m crossvein) and the structure of the male terminalia (mainly the shape of the distiphallus and basoventral process), the new species appears to be most closely related to C. marriott . It significantly differs from its congeners, however, in the shape of the lateral extension of the basiphallus, which terminates in a sharp point.

Type material examined. REPUBLIC OF CONGO: holotype ³, “REPUBLIC OF CONGO 349m / Likouala Prov. , Nouabale-Ndoki / National Park , Makao forest / (Secondary forest) / 02°36′42.5′′N, 17°09′23.8′′E / 23– 28.ix.2022 Malaise Trap / Dérozier, V., Fouka,B., / Kirk-Spriggs,A., Takano, H. Leg. / ANHRT:2022.14 // HOLO- TYPE ³ / Curtonotum / ndoki / A.H. Kirk-Spriggs 2022 [printed; red border]” (deposited ANHRTUK # 00273380). In excellent condition; micro-pinned and staged; dissected, abdomen and terminalia in micro-vial pinned beneath specimen .

Distribution: Republic of Congo.

Bionomics: Occurring in disturbed Guineo-Congolian rainforest ( Fig. 8 ).

Amended couplets from the identification key provided by Kirk-Spriggs & Wiegmann (2013: 53). To avoid confusion, “fig.” or “figs” is applied below to denote figures in Kirk-Spriggs & Wiegmann (2013) and “Fig.” or “Figs” for figures in this paper.

5. Lateral margin of basiphallus with angulate, sub-rectangular extension (fig. 224); male sternite 6 with lateral margins gently curved and U-shaped apical excision (fig. 218); dm–m crossvein as illustrated in fig. 163; spermatheca (fig. 213)..................................................................................... C. marriott Kirk-Spriggs, 2013

- Lateral margin of basiphallus either with finger-like, evenly-rounded extension and serrated edge (figs 225, 226), with fingerlike, evenly-rounded extension and shallow, wide apical excision (fig. 227), or with lateral margin terminating in acute spur-like process ( Fig. 7 ); male sternite 6 with lateral margins rounded or straight with V-shaped apical excision (figs 219, 220; Fig. 5 ); spermathecae (figs 214, 215)............................................................................ 6

6. Lateral margin of basiphallus with finger-like, extension and serrated edge (figs 225, 226); male sternite 6 with shallow Vshaped apical excision (fig. 219); dm–m crossvein as illustrated in Fig. 164; spermatheca (fig. 214)................................................................................................. C. moffatt Kirk-Spriggs, 2013

- Lateral margin of basiphallus with finger-like, evenly-rounded extension and shallow, wide apical excision (fig. 227); male sternite 6 with narrow V-shaped apical excision (fig. 220); dm–m crossvein evenly curved as illustrated in fig. 165; spermatheca (fig. 215); female unknown........................................................... C. platyphallum Tsacas

- Lateral margin of basiphallus terminating in acute spur-like process ( Fig. 7 ); male sternite 6 with wide V-shaped apical excision ( Fig. 5 ); dm–m crossvein angulate as illustrated in Fig. 4 ; female unknown.......................... C. ndoki sp. nov.

Figures

FIGURE 8. Type locality of Curtonotum ndoki sp. nov. Gressitt & Gressitt-type Malaise trap deployed over a stream in Guineo- Congolian rainforest, Nouabalé-Ndoki National Park, Republic of Congo. Photograph V. Dérozier.

FIGURES 1–4. External features of holotype of Curtonotum ndoki sp. nov. (abdomen removed for dissection) 1. Head and thorax (lateral view). 2. Head, scutum and scutellum (dorsal view). 3. Frons and face (frontal view). 4. Wing (dorsal view). Scale bars: Figs 1, 2 & 4 = 1.0 mm, Fig. 3 = 0.5 mm.

FIGURES 5–7. Male terminalia of holotype of Curtonotum ndoki sp. nov. 5. Sternite 6 (ventral view). 6. Hypandrium and epandrium (lateral view). 7. Phallus (right lateral view) (ejaculatory apodeme missing). Scale bars = 0.2 mm.