Ptilocerembia qiului, Chen & Xiong & Jiang, 2025

Ptilocerembia qiului sp. nov.

Type locality.

China, Yunnan Province: Yuxi City, Ailao Mountain, Yingpan   GoogleMaps , 23.9901°N, 101.5476°E (Fig. 1 View Figure 1 ), 2000 m, on road surface, 23 May 2018. V. 23; L. Qiu leg.

Type specimens.

Holotype: • ♂, in alcohol. Original label: “ China, Yunnan, Yuxi, Ailao Mountain, Yingpan , 23.9901°N, 101.5476°E, 2000 m, 23 May 2018. V. 23, L Qiu ”, “ HOLOTYPE / Ptilocerembia qiului sp. nov. / Det. Chen ” ( ICJUST) GoogleMaps . Paratype: • 1 ♂, with same collection event label as the holotype and additional label “ PARATYPE / Ptilocerembia qiului sp. nov. / Det. Chen ” ( ICJUST) GoogleMaps .

Diagnosis.

Ptilocerembia qiului sp. nov. is assigned to the genus Ptilocerembia of family Ptilocerembiidae by the antennae with long erect setae and white distal segments, bifurcated MA in all wings, hind basitarsus with dense ventral setae and only one papilla, tergite X obliquely divided into two unequal sclerites with the area between the hemitergites depressed, MF with a hook, elongated HP, and the fused left cercomeres ( Miller et al. 2012; Poolprasert and Edgerly 2014). Among the five known species of Ptilocerembia (see Suppl. material 1: table S 1), P. qiului sp. nov. is the most similar to P. catherinae based on the 10 R with a median convex along left margin, MF with a raised nodule near base of EP, and LC 1 with a large echinulate nodule ( Poolprasert and Edgerly 2014). However, P. qiului sp. nov. can be distinguished from P. catherinae by the submentum with anterior margin truncate (concave in P. catherinae ), MS with broad right half (absent in P. catherinae but similar to that of P. rossi ), 10 LP and 10 RP broad (narrow in P. catherinae and other species), HP elongated and specialized apically (relatively short and simple in P. catherinae and other species) ( Friederichs 1923; Poolprasert and Edgerly 2014). The dichotomous key in Poolprasert and Edgerly (2014) could separate P. catherinae as well as its similar species, P. qiului sp. nov. from other congeners.

Description.

Male: Body length (from anterior of maxillary palps to cercal apex) ca. 15 mm; color pale to brown (Fig. 2 A, B View Figure 2 ).

Antennae at least 26 - segmented, most segments brown and covered by long erect setae, distal segments pale (Fig. 2 C View Figure 2 ). Head capsule dark brown (Fig. 3 A, B View Figure 3 ), near 1.5 times longer than wide, with reticular pigmentation on posterior 1 / 3. Eyes small, sides behind eyes rounded, gradually converging posteriorly. Clypeus broad, pale brown; labrum semicircular, dark medially, pale laterally. Maxillary palpi dark brown, five-segmented; labial palpi brown and short, three-segmented. Submentum dark brown, subquadrate, slightly wider than long, anterior margin truncate, posterior margin slightly concave, lateral margins slightly convex.

Prothorax brown (Fig. 3 A View Figure 3 ), subquadrate, slightly wider posteriorly, much shorter and narrower than head, with subequal length and width, surface with deep transverse and longitudinal grooves. Meso- and metathorax generally brown, width subequal to head. Legs brown; hind basitarsus with single ventral papilla (Fig. 3 C View Figure 3 ). Wings pale brown (Fig. 4 View Figure 4 ), with longitudinal pale stripes; MA of all wings forked subbasally.

Abdomen dark brown (Figs 2 View Figure 2 , 5 View Figure 5 ). Terminalia with tenth abdominal tergite completely cleft, hemitergites separated basally (Fig. 5 A – E View Figure 5 ). MS transverse, sinuate, near fusiform, with a posterior notch on right half. Hemitergite 10 L broad, subtrapezoidal, left margin expanded to ventral side; 10 LP constricted basally, right margin rounded, left margin greatly projected leftward medially, apex blunt and curved leftward. 10 R broad throughout, inner margin sinuate, with a median convex; MF with a long sickle-shaped hook (EP) and a raised nodule; 10 RP broad, subquadrate, apex with left angle pointed and right angle notched. LPPT produced as a subtriangular thin sclerite beneath 10 L, sharp LPPT-P pointing backwards. LC 1 tubular basally, elongated, inner margin with a large echinulate lobe apically. LC 2 shorter than LC 1, subconical, basal fusion with LC 1 slightly constricted. Right cercus slightly longer than left cercus; RC 1 slightly shorter than RC 2, both covered with long setae and tapering towards apex. H broad (Fig. 5 F, G View Figure 5 ), rounded, lateral margins obliquely convex; a slender curved sclerite present posterolateral to H. HP near as long as H; right margin mostly straight except expanded basally and convex apically; left margin convex at basal half, forming a denticulate ridge at apical half.

Etymology.

The species is named after its collector, Dr. Lu Qiu (Mianyang, Sichuan, China).

Distribution.

China: Yunnan Province.

Biology.

The specimens were collected at a high-elevation site in the Ailao Mountain region, situated at the transitional boundary between the Yungui Plateau and the Hengduan Mountains. This area serves as a climatic divide between the Pacific Southeast Monsoon and the Indian Ocean Southwest Monsoon systems. The region experiences a subtropical montane climate characterized by cool annual temperatures, with mild summer conditions and cold winters. Precipitation is abundant and seasonally concentrated, with most rainfall occurring during an extended rainy season, while humidity remains consistently high throughout much of the year. The vegetation surrounding the habitat is dominated by extensive mid-elevation moist evergreen broad-leaved forests, recognized as one of China’s most significant subtropical montane wet evergreen broad-leaved forest ecosystems. These forests are primarily composed of species from the Fagaceae , Theaceae , Lauraceae , and Magnoliaceae and feature a rich diversity of epiphytes (including mosses and ferns) and lianas. This structurally complex, humid evergreen forest, combined with persistent mist and steep elevational variation, creates stable micro-habitats such as bark crevices, leaf-litter zones, and humid canopy niches that are favorable for webspinners. Given the pronounced vertical climate stratification of the region, the new species may occupy a narrow elevational range with specific humidity, canopy cover, and litter-substrate conditions. Future field studies targeting mid-montane evergreen forest corridors in the Indochina – Yunnan region may reveal a broader distribution of the genus across similar habitats.

Mitogenome characters

The complete mitogenome of P. qiului sp. nov. is 15,443 bp in length (GenBank accession No. PX 232380), which is slightly smaller than other reported webspinner mitogenomes (typically ~ 15.7–17.3 kb). It is a circular molecule comprising 13 protein-coding genes ( PCGs), 20 tRNA genes, and 2 rRNA genes, plus the A + T-rich control region (Fig. 6 View Figure 6 ). Two tRNAs, tRNA-Val (trnV) and tRNA-Ser (UGA) (trnS 2), are missing (a feature not seen in other embiopteran mitogenomes). The gene order is the canonical insect arrangement as in Drosophila yakuba Burla (1954) ( Clary and Wolstenholme 1985), with no rearrangements compared to the ancestral pattern (see Suppl. material 1: table S 2). Base composition is strongly A + T-biased (A 39.2 %, T 25.1 %, G 7.8 %, C 27.9 %).

A notable feature is the presence of ~ 5.4 tandem repeat units in the intergenic region between tRNA-Ile and tRNA-Gln. Such repeated sequences have not been reported in other sequenced embiopteran mitogenomes. Tandem Repeats Finder analysis confirmed these repeats ( Benson 1999), whereas the control region itself contains no repeated sequences.

Most PCGs use standard invertebrate start codons (ATA, ATG, ATT) and terminate with TAA; six genes ( COX 1, COX 2, COX 3, ND 1, ND 4, ND 5) end with an incomplete stop codon (single T), which is presumed to be completed by post-transcriptional polyadenylation. Relative synonymous codon usage ( RSCU) analysis shows a strong bias toward A / T-ending codons; the most frequent codons encode serine (UCU, UCA) and threonine (ACC) (see Suppl. material 2: fig. S 1 A).

Analysis of selective pressure (Ka / Ks) for each PCG (vs. P. lanyuhensis ) yielded values <1.0 for all genes (see Suppl. material 2: fig. S 1 B), indicating overall purifying selection in the sequenced webspinners. COX 1 shows the lowest Ka / Ks (highest conservation), while ATP 8 shows a relatively higher rate (although still <1). The pattern that COX 1 is the slowest-evolving mitochondrial gene and an ATP synthase gene is the fastest is consistent with other Embioptera ( Chen et al. 2017) .

Molecular delimitation and phylogeny

The COX 1 barcode of P. qiului sp. nov. was compared to six available Ptilocerembia sequences from GenBank (except for P. senathami , for which COX 1 is missing). Pairwise K 2 P distances between P. qiului sp. nov. and other congeners ranged from 0.1259 to 0.1759 (see Suppl. material 2: fig. S 2), far exceeding the widely adopted intraspecific thresholds (~ 2 %) in webspinners and other insects ( Hebert et al. 2003; Chen 2022, 2023). The smallest distance among any congeners was 0.042 (between P. catherinae and P. thaidina ). In phylogenetic trees ( BI, NJ, and ML), P. qiului sp. nov. grouped with two unnamed Ptilocerembia specimens sequenced in Miller et al. (2012), rather than with any of the formally described species. The phylogenetic placement of the new species was supported by relatively strong topological values, with a posterior probability of 0.82 in the BI tree (Fig. 7 View Figure 7 ), a bootstrap value of 66 in the NJ tree (see Suppl. material 2: fig. S 3 A), and a bootstrap value of 52 in the ML tree (see Suppl. material 2: fig. S 3 B). These results indicate that the sequenced individual of P. qiului sp. nov. forms a distinct clade, consistent with its morphological uniqueness. In summary, both morphological and COX 1 data support the delimitation of P. qiului sp. nov. as a new species, divergent from its congeners.