Coriophagus bulbosus Hui & Hazra., 2025

Coriophagus bulbosus Hui & Hazra. sp. nov.

urn:lsid:zoobank.org:act:

GenBank Accession Number of holotype. PQ846630

Material examined. Holotype male, India, West Bengal, Darjeeling, Dudhia ( 26°50.2' N, 88°14.6' E), 26.10.2024, open light trap, Coll. A. Mondal. GoogleMaps

Diagnosis. The ensemble of traits listed below sets the adult male of the genus Coriophagus apart from the previously described species: detached vein R 2 is of the same width as R 3, and is half as long as R 3; R 4 and R 5 are not clearly differentiated, and appear to be a single, long vein; flattened trapezoidal tarsomere I of the forelegs; ninth abdominal sternite having a spherical outgrowth on its edge from where the aedeagus arises.

Etymology. The specific epithet “bulbosus ” refers to the Latinised term describing the spherical outgrowth located at the margin of the ninth abdominal sternite.

Description of adult male (n=1) ( Fig. 1 View FIGURE 1 )

Total length 2.91 mm (from tip of frons to caudal margin of tergite X); length of metathorax 1.25 mm; width of metathorax at scutellum 0.33 mm; length of antenna 0.7 mm ( Figure 1 View FIGURE 1 ).

Colour. Eyes dark red, head, and abdominal segments light brown, hind wings translucent with brown veins, metathorax dark brown, legs brown with end of tarsomeres pale white.

Head ( Figs. 2A View FIGURE 2 , 3A View FIGURE 3 ). Transverse, wider than metathorax; length 0.36 mm, width 0.75 mm. Eyes separated by 0.3 mm. Eyes protruding with 14–16 dorsal and 10–13 ventral ommatidia. Interommatidial space conspicuously pubescent. Head very well sclerotised, antefrons not prominent, rather depressed. Postfrons quadrilateral in shape. Sclerite next to eyes rectangular, and extending up to middle of each eye. In ventral view, mouth field sclerite as well as anterior opening of digestive tract clearly visible. Sclerite of postmentum rectangular strip-like in appearance.

Antennae ( Figs. 2B View FIGURE 2 , 3B View FIGURE 3 ). Antennae originating from sides of antefrons with numerous hemispherical chemoreceptors, seven-segmented with a broad, flat flabellum on each antennomeres III–VI; scapus (antennomere I) 0.1 mm long, cylindrical in shape; pedicellus (antennomere II) 0.04 mm in length, tiny, urn-shaped, wider at middle than base or apex; antennomere III 0.5 mm long, bearing longest flabellum; antennomere IV 0.44 mm long; antennomeres V and VI both 0.42 mm long; antennomere VII 0.41 mm long; antennomere III longest and antennomere VII broadest. Scapus and pedicellus with no sensory pits while antennomeres III–VII having numerous sensory pits of nearly identical size.

Mandibles ( Figs. 2C View FIGURE 2 , 3C View FIGURE 3 ). 0.09 mm long, strongly sclerotised, conical in shape and not crossing each other.

Maxillae ( Figs. 2D View FIGURE 2 , 3D View FIGURE 3 ). Two-segmented, with corpus 0.02 mm long and palp 0.08 mm long; palp attached to apex of maxillary base, of same width that of base and almost four times as long as base, covered with long hairs and numerous small sensory pits.

Thorax.Pro- and mesothorax uniformly sclerotised,with no apparent features useful for diagnostic differentiation. Prothorax band-like, narrower than interocular distance of 0.3 mm. Mesothorax wider than prothorax, rectangular in shape, connected to metathorax by a pale brown membranous region. Metathorax ( Figs. 2E View FIGURE 2 , 3E View FIGURE 3 ) markedly enlarged and heavily sclerotised than preceding thoracic segments. Prescutum 0.31 mm long and 0.21 mm wide, nearly triangular; antero-lateral margins well separated from scuti at both sides; postero-lateral margin not well defined. Scutum 0.32 mm long, 0.14 mm wide, rhomboid in shape, not well defined along inner margins. Scutellum broadly pentagonal, 0.2 mm in length and 0.33 mm in width. Postlumbium 0.05 mm long and 0.27 mm wide, slightly less sclerotised than rest of parts of metathorax, trapezoidal in shape with both anterior and posterior margin straight. Postnotum 0.58 mm long and 0.36 mm wide, ‘U’ shaped with rounded posterior margin.

Reduced mesothoracic wings ( Fig. 2G View FIGURE 2 , 3F View FIGURE 3 ). 0.48 mm long.Apical part globular with 0.09 mm width, basal stalk much narrower, almost half width of apical part, 0.04 mm.

Hind wings ( Fig. 2H View FIGURE 2 , 3G View FIGURE 3 ). Broad, fan-shaped, spanning 1.75 mm from base to middle of radial sector and 1.82 mm from base to edge of subcostal margin. C+Sc united, dark brown, 1.03 mm long, reaching a little more than half of wing length. R 1 vein 1 mm long, basally attached to R 4 vein, having some isolated dark spots along apical 1/3 rd length. Area between Sc and R 1 pigmented, pigmentation getting darker from apical 1/3 rd region of both veins, extending beyond their apices along wing margin, to some distance creating a leaf-like shape. R 2 vein detached, 0.52 mm long, somewhat curved, slightly broader than detached R 3 vein. R 3 vein 1.04 mm long, twice length of R 2, distal 3/4th portion forming a broad downward curvature. R 4 straight, basally unified with R 1, 1.01 mm in length, having a darkly pigmented patch on its apex. R 4 and R 5 appear confluent with no clear separation. Nonetheless, a faint, depigmented region at mid-length indicating a possible boundary. Based on this, R 5 vein detached, 0.68 mm long, having a slight upward curvature, terminating close by wing margin. MA 1.4 mm long arising below base of R 4 and diverged, ending near wing margin. CuA 1.2 mm long running parallel to MA but slightly shorter in length than MA, CuP vein 0.87 mm in length, lying close to anal margin, darkly pigmented with undulating margin, almost as broad as R 2 vein.

Legs ( Figs. 2H–J View FIGURE 2 , 3J–L View FIGURE 3 ). Coxae of fore- and midlegs enlarged and flat. Inner margin of trochanterofemur of fore and midlegs and trochanter of hindlegs bearing hairs. Coxae of metathoracic legs fused with the metathoracic sclerites and hence metathoracic legs divided into trochanter, tibia and tarsus ( Kinzelbach 1971). Tarsi threesegmented, devoid of any claws. Basitarsus (tarsomere I) of forelegs enlarged, subtrapezoidal with rounded edges. Tarsomere II of all three pair of legs inserted in middle of dorsal surface of tarsomere I; tarsomeres II and III of all three pair of legs paddle-shaped with adhesive microtrichia ( Pohl & Beutel 2004). Tarsomere I of mid and hind legs with a pale sensory spot and distally terminating into an acute projection forming an auxillary claw ( Kinzelbach 1971; Kathirithamby 1989).

Measurements of several parts of legs as follows: forelegs—coxa 0.24 mm long, trochanterofemur 0.3 mm, tibia 0.3 mm, tarsomere I 0.08 mm, tarsomeres II and III 0.14 mm each; midlegs—coxa 0.3 mm, trochanterofemur 0.41 mm, tibia 0.44 mm. tarsomere I 0.13 mm, tarsomere II 0.15 mm, tarsomere III 0.15 mm; hindlegs—trochanter 0.17 mm, femur 0.4 mm, tibia 0.48 mm, tarsomere I 0.12 mm, tarsomere II 0.15 mm, tarsomere III 0.15 mm.

Abdomen ( Figs. 2K View FIGURE 2 , 3I View FIGURE 3 ). Ten-segmented, somewhat tapered towards posterior end. Sclerotised only at dorsal tergites and ventral sternites. Sclerotisation of tergites increasing gradually towards aedeagus, but ventral sternites nearly uniformly sclerotised throughout abdominal segments. First segment covered with postnotum of metathorax. Genital capsule i.e., abdominal segment IX strongly sclerotised, ovate shape; proctiger i.e., abdominal segment X minute in size bearing a spherical outgrowth on its edge from which aedeagus arises.

Aedeagus ( Figs. 2K View FIGURE 2 , 3H View FIGURE 3 ). 0.14 mm long, hook-like, arcuately curved anteriorly, evenly tapering to apex, dorsal hook, and ventral prong prominent. Dorsal hook longer than ventral prong. Dorsal hook 0.05 mm long, with an acuminate tip and forming an acute angle of 40º with shaft; ventral prong 0.02 mm long, forming an obtuse angle of 130º with shaft. Angles of projection of dorsal hook and ventral prong with shaft of aedeagus giving distal margin a sinuate, arched semblance.

Female. Unknown.

Host. Unknown.

Remarks. Coriophagus bulbosus Hui & Hazra , sp. nov. belongs to the genus Coriophagus owing to the presence of robust head sclerites, distinct frontal and epistomal sutures, sclerotised mandibles, the distal end of fore tibia spatulate with enlarged foretarsomere I ( Kinzelbach 1971; Kathirithamby 1989, 1992). The following combination of attributes confirms that Coriophagus bulbosus is a novel member of the genus Coriophagus : i. trapezoidal foretarsomere I, with rounded edges, ii. detached vein R 2 is of same breadth of R 3, iii. R 2 is half as long as R 3, iv. R 4 and R 5 not clearly demarcated, and appears to be a long, single vein, and v. proctiger having a spherical excrescence on its edge from where the aedeagus appears.

The antennae of the newly described species conform to the general morphology observed in all previously described congeners. The wing venation of the newly described species somewhat resembles C. rieki , C. hansoni , and C. latimanus but differs in the shape of foretarsomere I, proctiger and aedeagus; shape of the aedeagus is similar to that of C. adebratti , and C. medleri , but differs from them in the shape of foretarsomere I and relative length of maxillary palp and base.

Two other Coriophagus species have already been described from India, in addition to the recently discovered species. The following are some notable differences between the newly described species and the previously recognised species from India —

• in C. calcaneus Roy & Hazra, 2016 mandibles overlap, base of the maxilla i.e. corpus is longer than the maxillary palp, width of the R 2 detached vein is much greater than that of R 3, aedeagus is devoid of ventral prong; while in C. bulbosus mandibles do not overlap with each other, maxillary palp is about two times longer than base, R 2 detached vein is not significantly wider than R 3, and aedeagus possesses both dorsal hook and ventral prong.

• in C. chaudhuri Hui & Hazra, 2023 width of the R 2 detached vein is much greater than that of R 3, foretarsomere

I oval shaped, maxillary palp slender, more than two times longer than the base with pointed tip, while in

C. bulbosus R 2 detached vein is not significantly wider than R 3, foretarsomere I trapezoidal in shape, and maxillary palp clubbed with blunt apex.

• The newly described species differs from other Oriental species of the genus Coriophagus i.e. C. adebratti and C. borneoensis in the shape of foretarsomere I, relative length of maxillary palp and base, and edifice of metathoracic sclerites.

Combination of characters provided in the diagnosis validates C. bulbosus as a new member of the genus Coriophagus .