Stigmella molinensis van Nieukerken & Snyers

van Nieukerken, Erik J., Doorenweerd, Camiel, Nishida, Kenji & Snyers, Chris, 2016, New taxa, including three new genera show uniqueness of Neotropical Nepticulidae (Lepidoptera), ZooKeys 628, pp. 1-63 : 18-22

Taxon classification Animalia Lepidoptera Nepticulidae

Stigmella molinensis van Nieukerken & Snyers sp. n.

Holotype male.

Peru, Lima, Universidad Agraria la Molina, 240 m, -12.0869, -76.9444, 1.xii.2010, leafmines on Salix humboldtiana , e.l. 16.xii.2010, C. Snyers, genitalia slide EvN4218, RMNH.INS.24218 (UNALM).

Differential diagnosis.

Externally Stigmella molinensis can be confused with other Neotropical Stigmella without fascia, with pale head and collar, such as Stigmella hamata Puplesis & Robinson, 2000, Stigmella montanotropica Puplesis & Diškus, 2002 and Stigmella austroamericana Puplesis & Diškus, 2002, but the male genitalia are characteristic.

Description.

Male (Figs 7, 64, 65). Head: frontal tuft orange, collar and scape yellowish white, flagellum brown. Antenna with 24 segments. Thorax and forewing fuscous, with dark tipped scales, a more or less distinct cilia line, demarcating the grey fringe; forewing without pale spots. Hindwing narrow, grey. Hindlegs fuscous with white parts, other legs yellowish white.

Female (Fig. 8). Antenna with 19-23 segments (n=4).

Measurements. Male: forewing length ca 1.9-2.0 mm (n=2), wingspan: 4.4-4.5 mm. Female: forewing length 2.3 mm, wingspan 5.1 mm.

Male genitalia (Figs 48-53). Total length capsule 240 µm (n=2). Uncus narrow, bilobed, with deep medial notch. Gnathos narrow, with posterior processes fused basally, distally just separate. Valva 155-170 µm long, with short pointed and curved distal process, inner lobe broad, rounded, with almost straight, parallel inner margins; transtilla with sublateral processes ca half as long as transverse bar. Phallus length 250-260 µm, vesica with many small denticulate cornuti.

Female genitalia (Figs 54-57). Total length bursa ca 730 µm. Abdominal tip rather narrow, but not pointed; T8 with 5-7 setae on either side, and a small patch of many small setae anteriorly; anal papillae without setae. Bursa covered with small pectinations, with a band of larger and stronger sclerotised ones, in 4 rows, running around bursa longitudinally; ductus spermathecae straight, without convolutions.

Biology.

Host plant (Figs 58, 59). Salicaceae : Salix humboldtiana Willd., a small tree.

Leafmines (Figs 60-63). Mine first a narrow gallery, usually running towards leaf edge and leaf apex and not doubling back, occasionally running to leaf base and then often doubling back and ending towards apex. Later mine a wide irregular gallery, almost full depth. Frass black, in a narrow central line. larval exit hole on leaf upperside.

Egg. Always deposited on leaf upperside close to the midrib.

Larva yellow.

Voltinism and habits. Larvae were always present between December and late January. Adults usually emerged after two to three weeks after the cocoon was spun, suggesting multiple generations. The species has only been searched for between early December and late January, we have no information on other seasons. Mines were always found at the shady side of the trees.

Distribution.

Peru: Lima.

DNA barcode.

We barcoded three specimens: the Holotype, the female RMNH.INS.24219 and the male RMNH.INS.24812. BIN: BOLD:ACG9223. The female was also sequenced for other genes and used in the molecular phylogeny ( Doorenweerd et al. 2016). Sequences may be retrieved in BOLD and Genbank under voucher/sample ID RMNH.INS.24812.

Remarks.

This species clearly belongs to the Stigmella salicis group s.str., that is widespread in the Holarctic region and of which all but one species feed on Salicaceae (sensu stricto). However, morphologically it differs by the presence of numerous small cornuti in the phallus, whereas all other species have a reduced number of differently shaped cornuti; the latter thus is a good apomorphy for the Holarctic members of the group. The female shares the characteristic apomorphy: a band of signa around the bursa copulatrix. In our molecular phylogeny ( Doorenweerd et al. 2016) Stigmella molinensis is sister to all Holarctic species of the group. The other Neotropical species, included in the salicis group by Puplesis and Robinson (2000) are excluded by us and placed in the Stigmella epicosma group of which probably many feed on Asteraceae . Since the host plant, Salix humboldtiana , and ten other native Salix species ( Alford and Belyaeva 2009) are widespread in South and Central America, we expect that Stigmella molinensis and possibly related species are more widespread.

Etymology.

The specific name, an adjective, is derived from La Molina, Spanish and Latin for Mill, and also the name of the district in Lima and the University where the species was collected.

Other material examined.

Adults and leafmines: Same data as Holotype, Peru, 1♂, 18.i.2010, e.l. 1.ii.2010, damaged specimen (see Figs 64, 65); 1♀, Genitalia slide EvN4219, RMNH.INS.24219; 3♀, xii.2013, e.l. xii.2013; 1♀ i.2013, e.l. i.2013; 1♂, 1♀, 15.xii.2014, e.l. i. 2015, ♂ Genitalia slide EvN4812, RMNH.INS.24812 (all RMNH).