Tritonaclia kefersteinii ( Butler, 1882 )

Przybyłowicz, Łukasz & Wiorek, Marcin, 2023, The first description of the female of Tritonaclia kefersteinii (Butler, 1882) (Lepidoptera: Erebidae: Arctiinae: Syntomini), the type species of its genus, Zootaxa 5351 (4), pp. 475-482 : 476-479

Tritonaclia kefersteinii ( Butler, 1882)

Hydrusa kefersteinii Butler 1882 : Cist. Ent. 3(26): 2; holotype: ♁, by monotypy, in the original description as ♀, in error; TL: “Ankafana” [sic!], “in the forest”

Material (2 specimens) 1♀, 12.ii.2018, Sava, Marojejy NP, camp 3, trap 11 (1320 m), 14.4367°S, 49.7434° E, lgt. C. Lopez-Vaamonde, MNHN-EL83626, preparation ♀ No. 123; 1♁ as above, but 10.ii.2018, camp 3, trap 8, MNHN-EL83627, preparation ♁ No. 124.

Female description. Diagnosis. Generally, the black ground colour and pale pattern of wings, consisting of several blotches, make the female of T. kefersteinii similar to the members of Melanonaclia Griveaud, 1964 as well as Tritonaclia Hampson, 1898 . However, it is easily distinguishable from all known Melanonaclia species by the much longer forewing, which in the largest specimens of Melanonaclia does not exceed the length of 20 mm, while in T. kefersteinii is 22 mm. Additionally, T. kefersteinii is the only taxon within Melanonaclia and Tritonaclia with a series of three pale postdiscal blotches (m 4, m 5, and m 6), which are of similar size and well separated from each other. Although the same arrangement of blotches is present in Melanonaclia , in that genus the subtornal ones (m 5 and m 6) are almost fused, separated only by the vein M3. Other Tritonaclia spp. also possess three separate postdiscal blotches, but in that case, the middle one (m 5) is minute (like a dot), while the subtornal one (m 6) is larger than the subcostal blotch (m 4). Tritonaclia kefersteinii is also unique among Melanonaclia (except for M. moerens (Oberthür, 1911)) and Tritonaclia species in possessing three distinct blotches in subbasal and discal areas. Finally, the important distinguishing character is the morphology of scales covering the blotches of the fore wing: in T. kefersteinii (as well as in T. quinquepunctata ) they are of a regular shape and very pale yellow to creamy ( Fig. 1A–C ), while in the other species of Tritonaclia and in Melanonaclia the forewing blotches are semi-transparent, covered with smaller, scarce and pure white scales. However, in T. quinquepunctata the forewing is more elongate and less rounded at the tip than in T. kefersteinii .

In genitalia, the female of T. kefersteinii is unique by its prominent, elongated signum along corpus bursae, without any narrowings, which may suggest that it consists of two merged plates ( Fig. 1D ). Signa of the other species of Melanonaclia and Tritonaclia usually consist of one to three differently expressed, and always wellseparated plaques, produced with spine-like protrusions. It should be considered, however, that the female of T. quinquepunctata , and T. tollini ( Keferstein, 1870) remain unknown.

Description ( Fig. 1A ). Head. Proboscis well developed, ochraceous-yellowish; head entirely dark brown, covered with elongate scales, vertex also with admixture of piliform scales; labial palpi 3 segmented, bent upwards, 1/2 extending beyond frons, 2nd palpomere distinct, wide and 3x as long as wide, 3rd palpomere of 1/2 of the width and 1/2 of the length of 2nd; antennae filiform, dark brown, each mere lateroventrally with a pair of elongate ochraceous setae.

Thorax. Patagia dark brown with admixture of ochraceous brown, covered with both elongate and piliform scales, laterally with small yellow blotch of regular scales; tegulae basal portion with regular yellow scales, terminal portion and apex with piliform brown scales; thorax medially worn, with remnants of ochraceous-brown, regular scales; laterally above legs ochraceous-brown; metascutum covered with ochraceous brown piliform scales, metascutellum entirely worn; pleurites entirely ochraceous brown, covered with a mix of regular and piliform scales.

Legs. Entirely dark brown, with some admixtures of ochraceous-brown scales, especially on feet; additional tooth on claw present, on the ventral side; arolium present, laterally produced with setae; tarsi lateroventrally on margins with rows of spine-like setae, and terminally on dorsal side, over claws with pair of elongate setae.

Foreleg. Tibia around 3/4 of femur length, epiphysis present, 1/2 of tibia, (tibia and 1st tarsomere a bit longer than femur).

Midleg. One pair of ochraceous brown terminal spurs, distal slightly longer and of the length of tibia width.

Hindleg. One pair of ochraceous brown terminal spurs, distal slightly longer, of the width of tibia; additional pair of spurs in 2/3 of tibia; tibia slightly widening till 1/3, then of equal width.

Abdomen. First tergite entirely ochraceous brown, covered with both regular elongate, and piliform scales; terga 2nd – 6th dark brown, laterally on each side on terminal margin irregular, slightly elongate yellow blotch; tergite 7th entirely dark brown, tergite 8th dark brown, laterally in distal half with irregular yellow blotch, not reaching the terminal margin, which is entirely dark brown; sterna dark brown, medially with admixture of some ochraceous-brown scales; sternite 8th deeply incised, medially with subtriangular protrusion in front of ostium bursae, making the entire incision W-shaped; laterally entirely dark brown.

Forewing. Subtriangular, length of costa 22 mm (n=1). Ground colour dark brown to almost black, with one yellow and six pale yellow, almost creamy blotches, two in basal, two in medial and three in distal portion of the wing; all blotches, except first basal, of similar shape and size, not semi-transparent, entirely covered with regular scales; first basal blotch (fm 1) narrow, elongate, yellow, separated from hind margin by a very narrow stripe of brown scales; second basal blotch (m 3) between DC hind margin and 1A+2A, of irregular, drop-like shape, elongate towards wing hind margin and sharply terminated, pale yellow to creamy; first medial blotch (m 2) from below R (touching), of 2/3 of DC width, terminated before DC hind margin, irregular, subtrapezoidal; second medial blotch (fm 3) between M3 and CuA1, suboval, pale yellow to creamy; first distal blotch (m 4) irregular, suboval with straight inner margin, pale yellow to creamy; second distal blotch (m 5) between R5 and M1, subtriangular, pale yellow to creamy; third distal blotch (m 6) between M2 and M3, subsquare, well separated from m 5 by a stripe of brown scales, pale yellow to creamy; underside as upperside, but hind portion with slightly paler scales; R4 absent, retinaculum present; cilia brown, along hind margin brown scales (also along fm 1).

Hindwing. Oval, reaching to 1/2 of forewing, dark brown with pale yellow to yellow blotches; basal portion with large, pear-shaped blotch, below DC hind margin and CuA2, separated from wing basal margin by narrow stripe of brown scales, portion closer to wing margin yellow, remaining part pale yellow to creamy; in medial portion, between CuA1 and CuA2 small, suboval, pale yellow to creamy spot; in distal portion between CuA1 and M2 small round pale yellow to creamy spot, and between M3 and M2 small, irregular, subtriangular spot, the smallest one and of the same colour as the two above described; underside as upperside; cilia brown, along basal and hind margin piliform scales; frenulum present; distance between CuA1 and CuA2 approx. 1,5x longer than between CuA1 and M3; M2+M3 not fused, from the same point in DC lower corner, Sc+R completely fused, DC outer margin concave.

Remarks. The female is generally similar to the male ( Fig. 1A, B ), with indistinct sexual dimorphism expressed mainly by the males’ smaller forewing, length of costa 18 mm (n=1).The eyes of the examined male are proportionally larger (i.e. frons is narrower than in the female). The legs are identical, but without admixture of ochraceous-brown scales. On the abdomen the yellow blotch is present also on the 7th tergite, but less distinct, and marks on the 8th tergite have the form of small dots. The fore wing pattern is identical, and retinaculum is present; on the hind wing, the medial blotch between CuA1 and CuA2 is absent, and the second distal blotch between M2 and M3 is very indistinct, reduced to only a few pale yellow scales.

Based on the photos, the forewing pattern is uniform in the majority of the specimens, however, an additional small and elongate blotch may be present in the distal portion of the wing, below m 4, and separated from it by the vein M2. On the hindwing, the first distal blotch is always present, while the medial and the second distal blotches are differently expressed, from well developed to completely absent. Additionally, in some specimens the medial and first distal blotch are narrow and elongate instead of round.

Female genitalia ( Fig. 1D ). Opening of ovipore narrowly surrounded by dark, heavily sclerotized granules. Anal papilla broad and short, rectangular, densely scobinate, covered with moderately dense, soft, erect setae of various lengths. Subanal area prominent, subsquare, morphologically resembling anal papillae, provided posteriorly with a pair of elongate protuberances. Apophysis posterior slightly longer than anal papilla, well sclerotized, narrowly club-shaped. Apophysis anterioris slightly shorter, needle-like. Dorsal pheromone glands in form of very long, narrow, membranous, and distinctly pleated tubules with a much shorter, narrow, membranous diverticulum in 1/3 of their length. Ventral pheromone glands absent. Ostium subovate, membranous. Lamella antevaginalis and lamella postvaginalis fused in form of a belt surrounding ostium. Lamella postvaginalis broadly fused with anterior portion of 8th sternite. Sternite 8th narrow, with conspicuous postero-median concavity. Ductus bursae basally narrow, membranous then distinctly sclerotized and posteriorly widened into prominent cervix bursae. Corpus bursae subovate, membranous, densely plicate. Signum in form of prominent, sclerotized, longitudinal plate along of corpus bursae. Ductus seminalis narrow, membranous originating laterally from central portion of ductus bursae.

Male genitalia redescription ( Fig. 1E, F ). The male genitalia of T. kefersteinii were described and illustrated for the first time by Griveaud (1964, p: 76, figs 181–183). However, that description is very short and the drawings, especially the one depicting the phallus, are inaccurate. Therefore, a detailed description supplemented with illustrations is provided below.

Tegumen well developed, broad, moderately sclerotized; lateral margin with directed ventrally, lobate, flattened protrusion densely covered with numerous setae; ventral portion narrowing towards connection with vinculum. Uncus prominent, in form of a sclerotized tube, terminated with ventrally directed hook and sublaterally covered with numerous, elongated, protruding setae. Vinculum narrow, moderately sclerotized. Saccus short, and subtriangular. Juxta weakly sclerotized but well developed, x-shaped, with arms surrounding phallobase more extensive (however this character is not correctly visible in Fig. 1E ). Valva elongate, moderately sclerotized, sacculus half length of valva, then transformed into a prominent, sclerotized, hook-like process directed distally along the ventral surface of valva; near costa small patch of protruding setae ventro-medially; terminal portion of valva more membranous, tapering into a dull termination and covered in subsaccular zone with short, protruding setae.

Phallus short, broad, straight. Vesica elongate, tubular, the width of phallus, terminated with a patch of prominent, sclerotized cornuti; ductus ejaculatorius membranous, originating from 2/3 the length of vesica, at base with indistinct membranous diverticulum and irregular scobinations.

Molecular remarks. The examined male and female specimens are confirmed to be conspecific also based on the molecular results, with the p-distance between COI-5P sequences of 0.00%.

Distribution. The species is known so far only from two localities ( Fig. 2 ). The first of them is the type locality, “Ankafana”, localised by Viette (1991) to be the forest of Ankafina, located 8 km south of Ambohimahasoa, in the area of Tsarafidy in Central Madagascar. However, the holotype is the only record from this locality known to us. All other specimens examined in MNHN (n=8) and NHMUK (n=2) were collected in Marojejy National Park in North East Madagascar. The species was recorded in an elevation range between 1140 and 1450 m.

Figures

FIGURE 1A–F. Tritonacliakefersteinii andT.quinquepunctata.A, T.kefersteinii, female habitus; B, T.kefersteinii, male habitus; C, T. quinquepunctata, male habitus, (Madagascar Nord, massif du Tsaratanana, versant Sud, 1850 m, Andohananalila, déb. III- 1967, P. Soga, MNHN-EL74626); D, T. kefersteinii, female genitalia; E, T. kefersteinii, male genitalia; F, T. kefersteinii, phallus with enlarged, everted region of vesica, black arrow—irregular scobinations surrounding the origin of ductus ejaculatorius; red arrow—indistinct, membranous lateral protrusion).

FIGURE 2. Distribution of Tritonaclia kefersteinii and T. quinquepunctata. Red dot—Ankafina, the type locality of T. kefersteinii, yellow dot—Tsaratanana, the type locality of T. quinquepunctata, green dot—Marojejy National Park, where both species co-occur.