Dactylotula phragmitella Liu et Yang, 2023

Yang, Huiduo, Teng, Kaijian & Liu, Tengteng, 2023, A new species and new record of the leaf-mining genus Dactylotula Cockerell (Lepidoptera: Gelechiidae) from China, Zootaxa 5336 (2), pp. 259-270 : 261-266

Dactylotula phragmitella Liu et Yang , sp. n.

( Figs 1–18 )

ḞṪÑàffi [Chinese name]

Diagnosis. This new species is similar to Dactylotula kinkerella and D. altithermella in both forewing and the male and female genitalia, but can be distinguished by the following characters. In the new species, terminal half of the valva in the male genitalia is elliptic, densely covered with coarse setae, uncus is bilobed and saccus is rounded distally ( Figs 6–9 ); in the female genitalia, a concavity is present at the middle of the dorsal margin of the papilla analis, posterior apophysis is about 1.5 times as long as the anterior apophysis, and the signum is absent ( Figs 10–11 ). However, in the male genitalia, in D. kinkerella , the distal part of the valva is broad and waterdrop-shaped with short thick protuberances distributed in bands except for the normal setae on median part ( Nel & Varenne 2012: figs 4, 8; Elsner et al. 1999: Pl. 2); in D. altithermella , the uncus is claw-shaped at the end ( Elsner et al. 1999: Pl. 2). In the female genitalia, in D. kinkerella , papilla analis is slightly rectangular in shape; in D. altithermella , a protuberance is present at the basodorsal corner of the papilla analis; in D. kinkerella and D. altithermella , the anterior and posterior apophysis are equal in length, and both have a pair of signa ( Elsner et al. 1999: Pl. 42).

Type material. Holotype, ♂, CHINA: Shandong, Dongying, Yellow River Delta National Nature Reserve , 37.45°N, 118. 59°E, 0 m, 4.viii.2018, leg. Tengteng Liu, Zhenquan Gao, Encui Wang & Mengfei Li, SDNU. Ent 171397, BOLD process id. INSSD3882-21 ( SDNU).

Paratypes (all China): 4♂, 1♀, 6.viii.2017, other data same as holotype, SDNU. Ent 171864 ( YELR004-23 ) , SDNU. Ent 171918 ( YELR005-23 ) , SDNU. Ent 171880, SDNU. Ent 171740, SDNU. Ent 171693; 1♂, Shandong, Dongying , Dawenliu Station of Yellow River Delta National Nature Reserve, 37.450°N, 118. 012°E, 0 m, 6.viii.2018, mine on leaf of Phragmites australis , leg. Tengteng Liu, Encui Wang & Zhongfeng Jiang, field no. LTT00415, SDNU. Ent 001342; 1♂, 1♀, Shandong, Dongying , Dawenliu Station of Yellow River Delta National Nature Reserve, 37.760°N, 118.985°N, 0 m, 6.viii.2018, leg. Tengteng Liu & Encui Wang, SDNU. Ent 001025, SDNU. Ent 000925; 3♂, 3♀, Shandong, Dongying , Yellow River Estuary Protection Station of Yellow River Delta National Nature Reserve, 37.751°N, 118.955°E, 2 m, 17, 18.vii.2022, leg. Kaijian Teng & Huiduo Yang, SDNU. Ent 038026 (genitalia slide no. YHD0584 ♂, Process id: YELRD002-23 ), SDNU.Ent037932 ( YHD0579 ♂), SDNU.Ent037982, SDNU. Ent038201 ( YHD0580 ♀), SDNU.Ent037989 ( YHD0583 ♀), SDNU.Ent037896 ( YHD0582 ♀); 1♀, Shandong Dongying, Yiqianer Protection Station of Yellow River Delta National Nature Reserve, 38.050°N, 118.717°E, 2 m, 19.vii.2022, leg. Kaijian Teng & Huiduo Yang, SDNU. Ent038409 ( YHD0585 , Process id: YELRD003-23 ); 1♀, Shandong, Dongying, Zhiqing Town , 37.740°N, 118.898°E, 2 m, 16.vii.2022, leg. Kaijian Teng & Huiduo Yang, SDNU. Ent 037575; 1♂, Shandong, Yantai, Mt. Kunyu , Jiulongchi, 37.292°N, 121.692°E, 300 m, 17.vii. 2019, leg. Encui Wang, Yurong Jiang & Yehao Wang, SDNU. Ent 050875 ( YHD0581 , Process id: INSSD349-20 ) .

Adult ( Figs 1–3 ). Forewing length: 3.1–4.2 mm (HT = 3.5 mm). Head smooth, beige. Labial palpus about 1.5 times as long as diameter of compound eye, beige ( Fig. 3 ). Antenna about 3/5 length of forewing, scape and flagellum beige, becoming light brown distally. Thorax and tegula beige. Forewing with costa slightly arched, apex pointed; ground color beige, densely covered with pale brown scales, denser distally; brown oblique stripes on 2/5 of inner margin, broad at base with narrowing distally, outwardly oblique to half width of wing, sometimes with only a few brown scales; cilia beige, with scattered black scales. Hindwing and cilia uniformly greyish brown. Legs beige. Abdomen grey-brown dorsally, yellow-white ventrally; tufts of piliform scales on genital segments yellow-white.

Venation ( Figs 4–5 ). Forewing with discal cell about 3/4 length of wing, R 1 reaching costa at 3/5, R 2 and R 3 almost parallel, R 4 and R 5 stalked, R 5 preapical, M 1 and M 2 close at base and well separated distally, M 3 and CuA 1 almost parallel, CuA 2 apart from CuA 1 basally, closer to each other distally, 1A+2A bifurcated at base. Hindwing with deep sinus between apex and tornus, Sc+R 1 reaching apex, M 1 and M 2 reduced to two wing folds, CuA 1 and M 3 slightly arched, CuA 2 straighter.

Male genitalia ( Figs 6–9 ). Uncus bilobed ( Fig. 8 ), base almost as wide as valva, rounded distally with setae. Gnathos reduced. Valva symmetrical, slightly shorter than tegumen + vinculum + saccus, slightly S-shaped curved with inner setae scattered; base strongly sclerotized ( Fig. 9 ); terminal half elliptic, densely covered with coarse setae. Transtilla broken and slightly slender at ends. Saccus triangular with rounded tip from ventral view ( Fig. 6 ), arcuate from lateral view ( Fig. 7 ). Phallus approximately as long as terminal elliptic part of valva, gradually narrowing distally with a small horn-like protuberance at end.

Female genitalia ( Figs 10–11 ). Papilla analis densely covered with short setae, slightly rectangular in shape with a concavity at middle of dorsal margin. Posterior apophysis about 1.5 times as long as anterior apophysis, slightly thinner; anterior apophysis extending from antero-lateral angle of segment VIII. Ostium bursae proximal to the posterior margin of sternite VIII. Ductus bursae + corpus bursae membranous, six times as long as papilla analis, signum absent.

Biology ( Figs 12–24 ). The mine of the new species is located on the upperside of the leaf, mostly near its base. The larva mines into the upper epidermis as soon as hatched ( Fig. 13 ). The initial linear mine of the first instar larva extends along the leaf veins, then gradually becomes wider, 1.0~ 1.5 cm in length. The mine of the second instar larva has the width of three leaf veins, then continues to widen, after about 1.0 cm widens significantly to the width of 13 leaf veins, with a total length of about 1.5 cm ( Fig. 12 ). The mine of the third instar larva is slightly wider than the end of the mine of the second instar larva. It is impossible to determine the normal length of the mine of the third instar and the number of instars, due to parasitic influences and limitations of the mine specimens. Mature larva pupates in the distal part of the mine ( Fig. 17 ). During pupation, the frass in the mine are used to wrap the pupa. In the linear mine, the frass filled the entire mine but accumulated on the lateral side in the later stage ( Fig. 16 ). The dry mine is yellow-brown with dark brown margins. It can be easily found from both sides of the leaf ( Fig. 17 ). There are often one to three mines on a single leaf, sometimes as many as five ( Fig. 16 ). Mines of different instars can be overlapped in late July and early August.

Larvae are often parasitized by parasitoid wasps, presumably one or two species of the family Pteromalidae . The parasitized larva was unable to pupate. Two larval epicrania of different instars and one dry larval body killed by parasitoid were observed in a single mine ( Fig. 15 ). The epicranium of this dry larval body is located at the end of the mine. It is presumed that the larva was parasitized at the third instar and then died ( Fig. 14 ). Three to ten individuals of the parasitoid wasp in a single mine were observed ( Figs 21, 22 ) (two mines examined). The parasitoid wasps’ emergence holes could be observed on both surfaces of the mine ( Figs 19, 20 ). Pupal exuviae of the wasp and the adult that failed to emerge were left inside the mine ( Figs 23, 24 ).

Host plant. Phragmites australis (Cav.) Steud. (Poaceae) ( Fig. 18 ).

Distribution. China (Shandong).

Etymology. The specific name is derived from the genus name of the host plant added by the Latin suffix –ella. A noun in the nominative feminine singular standing in apposition to the generic name.

Figures

FIGURES 1–5.Adults and wing venation of Dactylotula phragmitella, sp. n. 1, male, holotype, SDNU.Ent171397, Dongying, China; 2, female, paratype, SDNU.Ent037575, Dongying, China; 3, lateral view, male, paratype, SDNU.Ent037982, Dongying, China; 4–5, venation; 4, forewing, female, slide no. YHD0585W; 5, hindwing, male, slide no. YHD0572W.

FIGURES 6–11. Male and female genitalia of Dactylotula phragmitella, sp. n. 6–9, male genitalia: 6, ventral view, paratype, slide no. YHD0579, arrow indicating strongly sclerotized valva base (phallus detached); 7, lateral view, paratype, slide no. YHD0584; 8, bilobed uncus, paratype, dorsal view, slide no. YHD0581; 9, left valva, paratype, slide no. YHD0584, arrow indicating strongly sclerotized valva base; 10–11, female genitalia, paratypes, slide nos: 10, YHD0583, 11, YHD0585, arrow indicating the concavity on the dorsal margin of papilla analis.

FIGURES 12–15. Parasitized leaf mine of Dactylotula phragmitella, sp. n. 12, leaf mine, yellow boxes indicating the position of larval epicranium and dry larva body killed by parasitism; 13, egg shell and the start point of leaf mine, arrow indicating egg shell; 14, opened leaf mine (black square indicating location of dry larva body killed by parasitism); 15, larval epicranium in two different instars and one larva body killed by parasitism, 15a, dry larva body killed by parasitism, arrow indicating larval cuticle, 15b, epicrania of first instar larva, 15c, epicrania of second instar larva.

FIGURES 16–18. Active mines and host plant of Dactylotula phragmitella, sp. n. 16, five mines (arrowed) on a single leaf; 17, distal part of mine with folded epidermis, circle indicating the position of pupa; 18, host plant Phragmites australis.

FIGURES 19–24. Parasitoid wasps of Dactylotula phragmitella, sp. n. 19–20, parasitoid wasp’s emergence holes (arrowed); 21–22, interior of parasitized leaf mines, blue arrows indicating pupal exuviae, red arrows indicating adult that failed to emerge, yellow arrow indicating larva that dried out by parasitism; 23–24, adult wasps, presumably one or two species of the family Pteromalidae.