A new species of Sacada Walker, 1862 from Thailand (Lepidoptera, Pyralidae, Pyralinae)

A new species of Sacada from northern Thailand is described: S. chaehomensis sp. nov. Pellinen & Zahiri (Lepidoptera: Pyralidae, Pyralinae). Morphological characters and DNA barcode data are provided for the new species, with a morphological comparison to S. dzonguensis and S. umtasorensis, and a DNA-barcode comparison to S. ragonotalis and S. albioculalis, respectively. After this addition, the current number of valid species in the genus Sacada is 43.


Introduction
The genus Sacada Walker, 1862 (Pyralidae, Pyralinae) has recently been the target of intensive systematic studies, and as a result its taxonomy has been considerably improved (e.g. Yamanaka 1995;Yamanaka 1998;Bae et al. 2008;Leraut 2013;Sutton et al. 2015). The latest work on the genus was performed by Singh et al. (2020), who described two new species of Sacada from India, described the new genus Pseudosacada Singh, Kirti & Ranjan with one species, provided a world checklist, and more importantly for subsequent research they provided good illustrations of adult moths and other morphological features. Currently 42 species are included in Sacada and the species are known from the Indo-Malay region, Australasia, the Afrotropics, and a few species from the Palearctic region (Singh et al. 2020;Nuss et al. 2003Nuss et al. -2020. Biology, life histories and females of many species are still unknown. The Australasian Sacada albioculalis Hampson, 1917 has been reared from Pometia pinnata (Sapindales: Sapindaceae), Intsia bijuga (Fabales: Fabaceae) and probably Trema (Rosales: Cannabaceae) in lowland Papua New Guinea, potentially being polyphagous (Scott Miller, pers. comm.). A distinct diagnostic feature of Sacada is the male's resting posture with forelegs stretched out in front, midlegs stretched out below and tip of abdomen pointing upwards. When the legs are stretched out, their massive hair tufts become visible (Fig. 1).
Only two Sacada species have been recorded from Thailand: S. decora Walker, 1862 and S. pyraliformis (Moore, 1879) (Singh et al. 2020, but online websites such as https://www.thaibugs.com provides photos of additional, potentially undescribed species).
A single Sacada specimen was collected from Lampang province, Northern Thailand in 2020 using mixed and UVlight. Comparisons with the literature, particularly Singh et al. (2020) revealed that it represents an undescribed species. Hence, we provide the description of the new species, Sacada chaehomensis sp. nov., based on morphology and DNA barcode sequence data, and give diagnostic characters distinguishing it from the most similar taxa.

Materials and methods
The abdomen and reproductive organs of the specimen (23.05.2020 / Thailand, Lampang/ Chae Hom 340 M / 18°43'19"N, 99°33'11"E) were prepared following standard methods (e.g., Hardwick 1950). The vesica was everted via caecum, which was cut open by placing the aedeagus inside a hypodermic syringe (Sihvonen 2001). Structures were photographed with a Leica DM1000 microscope (Wetzlar, Germany) and an integrated Leica DF295 digital camera. Several structures were photographed in two to six images of different depth of focus and combined into single images using image-stacking as available in Adobe Photoshop 19. The final plates were compiled in CorelDraw (v. 22). Morphological terms follow Klots (1970).
Total genomic DNA was extracted from one leg, using the DNeasy tissue extraction kit (Qiagen, Hilden, Germany) following the manufacturer's instructions. We sequenced the 5' region of the cytochrome c oxidase subunit I (COI5P) from the mitochondrial genome, known as DNA barcode (Hebert et al. 2003). PCR amplification and cleanup of the barcode region was performed at the Centrum für Naturkunde (CeNak, Hamburg, Germany) following the protocols of Wahlberg and Wheat (2008). The cleaned PCR products were sent to Macrogen Europe for Sanger Sequencing. The resulting chromatograms were checked and DNA sequences aligned by eye using BIOEDIT v. 7.0.4.1 (Hall 1999). Because CO1 is a protein-coding gene, pseudogenes can be detected through translation of the nucleotide sequence to ensure the absence of stop codons or frameshift mutations (performed in MESQUITE v. 3.61 (Maddison and Maddison 2019). The DNA barcodes of outgroups were taken from the BOLD, BARCODE OF LIFE DATA SYSTEM v4 (Ratnasingham and Hebert 2007). A gene tree was reconstructed using the Neighbor-Joining (NJ) algorithm and Bayesian Inference calculated with the analytical tools of BOLD and MrBayes v.3.2.7 (Ronquist et al. 2012), respectively. The Bayesian analysis was run for 8 million generations, with every 1000 th tree sampled. The dataset was divided into three sets by codon positions. The GTR+G model was chosen as the most appropriate model for COI sequence evolution with IQ-TREE (Trifinopoulos et al. 2016). There were only 18 public Sacada DNA sequences available on BOLD and GenBank to be applied to our analysis. The molecular data for the voucher specimen is available on BOLD (sampleID ZMH-DNA0199) and via GenBank accession number SUB8441214 (www. ncbi.nlm.nih.gov/Genbank). Description. Description is based on male, female is unknown. Wingspan 40 mm. Antennae with basal two thirds bipectinate, apical third fasciculate. Head, thorax and abdomen rufous. Tegula with iridescent scales of purplish-grey hue. Labial palps short. Base of proboscis covered densely with scales. Fore-and midleg tibia with massive hair tuft, spur formula of legs 0-2-4. Forewing narrow, reddish brown, medial, postmedial and terminal lines dry straw colored (fuscous). Medial line angled, postmedial line straight, forming triangular area on midwing. Terminal line narrow, fringes concolorous with wings. Hind wing wide, grey, weakly rufous near margin, veins darker. Terminal     Male genitalia. Uncus hood-shaped, curved, densely setose, with rounded lobes basolaterally. Gnathos sclerotised, arms forming narrow bands, arms fused medially forming upwards directed weakly dentate hook; basolateral parts curved inwards, lobe-shaped. Tegumen formed of two narrow plates. Valva simple, setose, pointing weakly outwards; costa straight. Transtilla large, sclerotised, plate-like, with distinct elongated, upwards directed projection medially, its apex blunt. Juxta broad, weakly constricted laterally, anterior margin even, posterior margin with two heavily sclerotised arms bearing few spikes. Vinculum narrow. Saccus elongated, apex round. Aedeagus stout and weakly undulating, caecum round, apical apodeme ventrally with small group of dentate spikes. Vesica large, simple, without distinct diverticula, basal part wider, apical part narrow and weakly curved; base covered with minute spikes, followed by minute sclerotisations, those become fewer towards vesica apex.

Results and discussion
Etymology. The species is named after its type locality, Chae Hom, in Lampang province, Thailand.
Biology. The single known male was collected in May 2020 at 340 m altitude; it was attracted to light in forest with diverse tree species, interspersed with small vegetable plantations (Fig. 9). Immature stages are unknown.
Distribution. The only specimen was collected in Lampang (Chae Hom) in northern Thailand.
Barcode analysis. A 642 bp barcode of Sacada chaehomensis sp. nov. was submitted to the identification engine on BOLD. Genetically nearest neighbors are unidentified pyralids from Malaysia, Sabah (North of Borneo) with a minimum divergence of 6.17% and another from Malaysia, North of Kuala Lumpur with 6.50%. The other pre-existing data for Sacada on BOLD were Sacada ragonotalis (6.54%) and Sacada albioculalis (8.93%), thus indicating that the unidentified pyralids may be Sacada sp. The species morphologically most similar (i.e., S. dzonguensis and S. umtasorensis) to the new taxon lacked representations on the BOLD DNA library. The tree topology generated by the BI analysis (Fig. 10) was very similar to the NJ-tree confirming the association (PP = 0.87) of the new species (ZMH199) with the sister pair of unidentified pyralids from Malaysia, Borneo (LPM-LY526-14+ LPMLY208-14) and Malaysia, North of Kuala Lumpur (LPMAL244-14+LEPML271-13). The relationships between analyzed Sacada must be treated with caution, because those are based on short DNA barcode sequences only, and are likely to change with addition of more molecular data and expanding taxon sampling.