Prochasma diaoluoensis, Liu & Stüning, 2024

Liu, Bo & Stuening, Dieter, 2024, Review of the genus Prochasma Warren (Geometridae, Ennominae, Boarmiini), with description of a new species from Hainan, South China, ZooKeys 1190, pp. 303-317 : 303

Prochasma diaoluoensis sp. nov.

Figs 2-7 , 8, 9 , 10-14

Type-material.

Holotype: male, China, Hainan Province, Lingshui, Diaoluoshan, 922 m, 20.IV.2023, Bo Liu leg. DNA barcode CRICATAS00001 (CRICATAS/ IZCAS). Paratypes (67 males, 7 females): 13 males 3 females, same locality and collector as holotype, 20.IV.2023, gen. prep. no. CRICATAS00064; 39 males 4 females, same locality and collector as holotype, 10.V.2023, gen. prep. no. CRICATAS00063, gen. prep. no. CRICATAS00071; 6 males, same locality and collector as holotype, 19.VI.2023; 9 males, same locality and collector as holotype, 19.VIII.2023. (CRICATAS/ IZCAS/ ZFMK).

Diagnosis.

Prochasma diaoluoensis is distinguished from its congeners by the following characteristics: 1) Valvae with a deep excavation on dorsal side near apex, basally adjacent a brush of modified setae present, absent in other species ( Sato 2023, in litt.); 2) Apex of uncus very short, not narrowly elongated; 3) female genitalia with an elongate, funnel-shaped, sclerotized structure on posterior part of bursa copulatrix and a spoon-shaped lamella postvaginalis; and 4) Ante- and postmedial lines reduced to small denticles, bordered by broad, white lines, more conspicuous than in the congeners. The latter two features are found, but less expressed, also in some other species. The same can be stated about the horizontal, yellow band, traversing both forewings, which is most conspicuous in P. mimica , less conspicuous in Prochasma diaoluoensis , but often present, at least in traces, also in the other congeners. Generally, the new species is, though more vividly coloured and with more strongly contrasting pattern, rather similar to its congeners, with exception of P. albimonilis which lacks the yellowish ground colour and has homogenous, dark grey pattern elements, almost not separated into basal, medial and postmedial areas. The female genitalia of Prochasma albimonilis are similar to P. diaoluoensis in the posterior part of bursa, which is also roundly extended on right side, but the sclerotized part is not funnel-shaped but rather broadly tube-like ( Sato 2019, fig. 40). It may even be a functional colliculum. In male genitalia, a narrow dorsal incision is present near apex of valvae in Prochasma albimonilis , but the valvae are broader, especially the sclerotized costal side, and more densely setose.

Description.

Forewing length: male 12.2-13.2 mm; female 12.9-13.6 mm. Head. Antennae bipectinate on basal two-thirds in males, rami long, length of longest rami about 9 times the diameter of the flagellum segments, filiform in females. Frons not protruding, covered with short scales, upper half pale, lower half dark. Labial palpus curved upwards beyond frons, covered with intermingled, dark and pale scales and longer hair-scales. Vertex with pale scales, a few dark scales near antennae. Thorax. Patagia and tegulae with lamellar, dark and pale scales, with longer, dark hair-scales on tegulae only, ventrally thorax covered with pale yellow hair-scales. Legs slender, pale, chequered black, hind tibia slightly dilated, with a pale scent brush in males. Forewings with apex angled, termen smoothly curved, without fovea in males. Hindwing with apex rounded. Wings yellow, covered with extensive black scales. Fringes with alternating yellow and smaller black parts. Forewing yellow, with distinct dark markings. Antemedial and postmedial lines both appear as consisting of a few black denticles or dots between M1 and CuA2, bordered by a broad, white band. In females, the denticles are more tooth-like. Submarginal line white, very fine, zigzag-shaped. Area between M3 and CuA1 appears as a yellow, horizontal band, with or without a few small black spots. Discal dot oval, black, faintly visible. Dark band on inner side of postmedial line of hindwing narrow, reaching from discal dot to inner margin. Dark band on outside broader, the width variable between individuals, slightly broader in females. Submarginal line visible, intermittent, weaker in hindwings. Underside similar to upperside, but more blurry and paler. Venation (Fig. 1 ). Forewing: R1 and R2 coincident; R1+R2 arising from upper vein of cell, then shortly anastomosing with Sc, and running almost parallel to the long stem of R3-4; stem of R3-5 arising shortly before anterior angle of cell; M2 from the middle of the discocellulars; CuA1 from before posterior angle of cell. Hindwing: Sc+R1 running closely parallel but not anastomosing with upper vein of cell at base; Rs from before anterior angle of cell; CuA1 from before posterior angle of cell; 3A absent. Pregenital abdomen. Dorsally scaled pale yellow, with a large black spot on each tergite. Ventrally with pale yellow hair-scales. Tympanal organs and a modified setal comb present, the latter as described in the generic description. Tergite and sternite of segment 7 short, length about 2/5 of width. Tergite and sternite of segment 8 elongate, length slightly greater than width in males, broader in females.

Male genitalia. Uncus triangular, base broad, with short setae dorsally, apex very short, not narrowly elongated. Gnathos with strong lateral arms, central part strong, rectangular, with rounded tip. Juxta rectangular, sclerotized, apex slightly narrowed. Saccus V-shaped, slightly extended. Valvae elongated, apically narrowed ventrally, tip rounded, with a deep excavation on dorsal side. Valve lamina proximally membranous, distally densely covered with setae, without a typical cucullus, with an oblique, sclerotized ridge between both parts. A tuft of long, curved, modified setae, tubular at base, distally flattened, present dorsally near the apex of each valva. Costa straight, sclerotized, basally slightly broadened, distally not reaching tip of valva, ending at excavation. Sacculus sclerotized, distally with a short, tooth-like process, protruding from ventral margin of valva at ¾ of its length. Aedeagus cylindrical, apically broadly elongated and sclerotized on one side. Cornutus short, not stick-like, apex tapering, with bulbous base.

Female genitalia. Ovipositor short, papillae anales narrow, tapering towards apex, covered with short setae. Anterior apophyses short, about 2/3 length of posterior apophyses. A thin needle-like sclerite, roundly enlarged anteriorly, present between the bases of posterior apophyses. Lamella postvaginalis large, spoon-shaped. Introitus bursae funnel-shaped, slightly sclerotized. Posterior part of bursa elongated, membranous, distally roundly extended on right side; outside with a posteriorly funnel-shaped sclerotized structure formed by a broad sclerite which consists of lamellar plates folded three times, with unknown function (see Figs 11-14 ). Anterior part of bursa slightly broader than posterior part, but no clear demarcation visible. Signum absent.

Etymology.

The specific name is derived from the type-locality, Diaoluoshan, Hainan Island, China.

Distribution.

China (Hainan).

Preliminary phylogenetic estimations

A barcode sequence based on the COI (658 bp) was obtained from the holotype of P. diaoluoensis and submitted to BOLD Systems (BIN: BOLD: AFJ0024, Sample ID: CRICATAS00001, Process ID: CCLEP001-23). There are currently 14 (including the one for P. diaoluoensis ) Prochasma -associated DNA barcoding records on BOLD Systems. Four of them are private and restricted to use only within BOLD Systems, and the remaining ten published records are available but contain nonidentifications and misidentifications. On the basis of the images of the specimens provided on BOLD, the locality information attached to the records and the provided barcode data, most specimens could be identified to species level. However, three species ( P. mimica , P. dentilinea , P. parasqualida ) are still not represented on BOLD, so a full phylogenetic analysis of the genus is not yet possible. However, based on the data currently available, the following preliminary conclusions can also be drawn: The neighbour-joining tree of Prochasma (Fig. 15 ) clearly shows that P. diaoluoensis is a distinct species and most closely related to P. albimonilis , with a mean genetic distance of 7.05% (p-dist) (Table 1 ). Interspecific genetic distances range from 4.9% to 8.7%, intraspecific values range from 0.3% to 2.0%. Furthermore, a phylogenetic tree, offered and constructed by BOLD Systems and based on the sequences of the "100 nearest neighbours", i.e., the species most closely related to P. diaoluoensis , showed that all sequenced Prochasma species clustered into a single clade of the phylogenetic tree. This is consistent with the results of our morphology-based study (see generic description and diagnosis). The three not yet sequenced species (i.e., P. mimica , P. parasqualida , P. dentilinea ) largely agree with the morphological characters of the others and will not change the homogenous character of the cluster, then representing the genus Prochasma .

Key to Prochasma species, based on characters of male genitalia

1	Apical region of valva with excavation or incision on dorsal side	2
-	Apical region of valva straight on dorsal side	3
2	Valva narrow, apex with a deep excavation dorsally, a brush of elongated, modified setae present near excavation; cucullus indistinct	P. diaoluoensis sp. nov. (Hainan)
-	Valva and costa broad, dorsally near apex with deep incision between both	P. albimonilis (Myanmar, Laos, Vietnam)
3	Cornutus on vesica narrow, stick-like	4
-	Cornutus on vesica not stick-like	5
4	Cornutus long, about half the length of aedeagus; dentate process on ventral margin of valva not prominent	P. mimica (India, Assam)
-	Cornutus shorter than one-third of aedeagus in length; dentate process on ventral margin of valva prominent	P. kishidana (Peninsular Malaysia, Borneo, Sumatra)
5	Apex of uncus stout and short; dentate process on ventral margin of valva rather short	6
-	Apex of uncus slightly elongated; dentate process on ventral margin of valva slightly longer	7
6	Valva narrow; tapering part of cornutus long; dentate process on ventral margin of valva conspicuous	P. squalida (Taiwan)
-	Valva broad; tapering part of cornutus shorter; dentate process on ventral margin of valva hardly visible	P. parasqualida (Vietnam, Laos, Thailand)
7	Cornutus large, long, base not bulbous, tapering part less than one-third the length of cornutus, with short, acute tip	P. dentilinea (India, Nepal, Myanmar, Thailand, Laos, Vietnam)
-	Cornutus smaller, base bulbous, tapering part nearly half the length of cornutus	P. sasakiana (Borneo)

Checklist of the Prochasma species

Figures

Figure 1. Wing venation of Prochasma diaoluoensis sp. nov.

Figure 15. Neighbour-joining tree of Prochasma taxa on the basis of DNA barcoding.

Figures 2 - 7. Adults of Prochasma diaoluoensis sp. nov. 2 male, holotype, upperside 3 male, holotype, underside 4 female, paratype, upperside 5 female, paratype, underside 6 male, paratype, living specimen 7 female, paratype, living specimen. Scale bar: 1 cm.

Figures 8, 9. Male genitalia of Prochasma diaoluoensis sp. nov. 8 paratype (vesica partly everted), gen. prep. no. CRICATAS 00063 9 paratype (brushes of modified setae removed, vesica not everted), gen. prep. no. CRICATAS 00064. Scale bar: 1 mm.

Figures 10 - 14. Female genitalia of Prochasma diaoluoensis sp. nov. 10 paratype, gen. prep. no. CRICATAS 00071 11 - 14 Close-ups of lamella postvaginalis, introitus bursae and posterior part of bursa 11 ventral view 12 dorsal view 13 lateral view from right side 14 lateral view from left side. Scale bars: 1 mm.