Chryxus willemsei Chen, Hartong & Cai 2026, n. sp.

Abstract

Chryxus willemsei Chen, Hartong & Cai, n. sp. (Figs 1-3) urn:lsid:zoobank.org:act: 7872D7FC-23BA-4D0E-AA0D-5A0DB3FDA172 TYPE MATERIAL. — Holotype. Suriname • ♂; Commewijne District, Mapana Creek; 25.VIII.1961; J. P. Schulz leg.; RMNH. INS. 1629746. DIAGNOSIS. — Body length 4.5 mm, generally blackish brown (Fig. 1); median longitudinal sulcus on posterior pronotal lobe wide in anterior portion, gradually narrowed posteriorly (Fig. 2A); apex of scutellum curved upwards (Fig. 2B); meso- and metafemora whitish in basal third, yellowish to blackish brown in apical parts (Fig. 1A, C); hemelytron with corium decorated with one broad, oblique, whitish band from base to inner angle, membrane with three clear whitish patches (Fig. 2D); paramere with one large, peculiar, branched process on inner surface, with upper branch short, triangular, lower branch long, spine-like (Fig. 3 C-E). ETYMOLOGY. — The specific epithet is dedicated to the Dutch entomologist Luc Willemse (RMNH) for his kind support to our study of the Reduviidae. DISTRIBUTION. — Suriname: Commewijne (Fig. 7). DESCRIPTION Male Coloration. Generally blackish brown (Fig. 1). Head dark brown, slightly darkened along interocular sulcus; collum lighter (Fig. 2A). Antennal scape and pedicel yellowish brown; flagellomeres dark brown (Fig. 1). Labium brown (Fig. 2B, C). Median longitudinal sulcus on posterior lobe of pronotum tinged with reddish brown. Scutellum with basal part slightly lighter (Fig. 2A). Thoracic sterna dark brown. Legs yellowish brown; meso- and metatrochanters and basal third of femora whitish; metafemur blackish brown on apical half; meso- and metatibiae dark brown to blackish brown, with basal and apical parts slightly lighter (Fig. 1A, C). Hemelytron with corium decorated with broad, oblique, whitish band from base to inner angle, apical half dark brown on inner half; clavus slightly lighter at apex; membrane dark brown, with three whitish patches (Fig. 2D). Abdomen dark brown, ventrally with one pair of longitudinal blackish bands laterally (Figs 1C; 2E); connexivum with faint, narrow, pale yellowish spot at base of each segment. Vestiture. Body surface smooth, slightly shiny, densely covered with suberect to erect, long and slender, whitish yellow setae, with setae on outer surfaces of tibiae, basal half of anterior margin of corium as well as apical portion of abdomen extremely long (Fig. 1). Head with ventral surface and collum glabrous. Antennal scape and pedicel with suberect to erect, short, whitish pubescence, with pubescence as long as or slightly longer than diameter of segment; flagellomeres with decumbent to suberect, short, whitish pubescence. Visible labial segments II and III with sparse, erect, short setae. Thoracic pleura and sterna largely glabrous; mesopleuron with tuft of erect, long, whitish setae along midlength (Fig. 2B, C). Hemelytron with clavus and outer half of corium shiny, membrane and inner half of corium dull (Fig. 2D); corium with some erect, long, blackish setae along Cu. Abdomen with one cluster of conspicuous lateral setae at connexival intersegmental suture III-VII (Fig. 2D). Structure. Head (Fig. 2 A-C) transverse elliptical, width across eyes 1.8 times as broad as length along midline; anteocular region twice as long as postocular, strongly declined anteriorly, near vertical; anteclypeus weakly elevated; gena with one small, posterolaterally produced, setigerous process. Eye (Fig. 2 A-C) large, reniform in lateral view, with posterior margin deeply concave; width across eyes 2.25 times as broad as interocular space. Antennal scape short and stout, 0.45 times as long as pedicel; pedicel slenderer, subequal to length of distiflagellomere; basiflagellomere slightly shorter than distiflagellomere. Labium (Fig. 2B, C) short and robust; visible segment I slightly shorter than visible segments II and III combined. Pronotum (Fig. 2A, B) 0.7 times as long as width across humeral angles, clearly divided into anterior and posterior lobes by transverse sulcus; anterior lobe subrectangle, weakly inflated dorsally, with one shallow, median, longitudinal depression on posterior fourth, anterior margin finely concave at midlength, anterior angle slightly protruding laterally, lateral margins subparallel; posterior lobe subtrapezoid, 1.5 times as long as anterior lobe, flattened on disc, with deep, median, longitudinal sulcus gradually narrowed posteriorly, humeral angles rounded and finely inflated. Prosternum (Fig. 2C) with broad stridulitrum. Scutellum (Fig. 2A, B) 1.17 times as long as basal width, strongly wrinkled, with short ridges and small pits; lateral portions on basal half and midline on apical half distinctly elevated, forming Y-shaped ridge; apex rounded, clearly curved upwards (Fig. 2B). Fore leg short; femur finely thickened; tibia slightly shorter than femur, gradually widened towards apex, with fossula spongiosa about one-fourth as long as segment (Fig. 1A, C). Mesotibia slightly longer than femur. Metatibia 1.33 times as long as femur, weakly curved (Fig. 1A, C). Hemelytron nearly reaching apex of abdomen (Fig. 2D). Abdomen elongate oval, 1.38 times as long as its maximum width, slightly flattened at midlength of ventral surface (Fig. 1C). Intersegmental sutures between sternites curved anteriorly at midlength (Figs 1C; 2E). Segment VIII broadly exposed, with posteromedial margin broadly concave as obtuse angle (Fig. 2E). Male genitalia. Pygophore (Fig. 3A, B) suboval, with large anterior and posterior openings, lateral margins subparallel, ventral surface somewhat flattened; transverse bridge long and narrow; median process long, knife-like, curved upwards, finely curved in apical half, narrowed towards apex. Paramere (Fig. 3 C-E) large, lobe-like, widest at midpoint, gradually narrowed towards apex, covered with short to long setae on apical two-thirds; inner surface with one large, peculiar, branched process, with upper branch short, triangular, apically blunt (Fig. 3C, D), lower branch long, spine-like, apically acute (Fig. 3D, E). Phallus (Fig. 3 F-H) relatively small; articulatory apparatus well sclerotized, basal plate arms short and divergent, ponticulus basilaris short and wide; basal plate extension long, wide, curved; phallosoma oval, dorsal phallothecal sclerite finely sclerotized, struts fused to each other, enlarged at midlength and narrowed apically; endosoma largely membranous, with two series of weaklysclerotized small spinus. Female Unknown. Measurements [in mm, ♂ (n= 1)]. Length of body (to apex of abdomen) 4.50; length of head 0.50; length of anteocular region 0.20; length of postocular region 0.10; width across eyes 0.90; interocular space 0.40; length of antennal segments I-IV= 0.40, 0.90, 0.70, 0.90; length of visible labial segments I-III=0.20, 0.15, 0.10; length of pronotum 1.00; length of anterior pronotal lobe 0.40; length of posterior pronotal lobe 0.60; width of anterior pronotal lobe 0.90; width of posterior pronotal lobe 1.40; median length of scutellum 0.70; basal width of scutellum 0.60; length of forefemur, tibia, tarsus=1.00, 0.80, 0.40; length of mesofemur, tibia, tarsus= 0.90, 1.00, 0.40; length of metafemur, tibia, tarsus =1.20, 1.60, 0.40; length of hemelytron 3.00; length of abdomen 2.20; maximum width of abdomen 1.60. REMARKS The holotype of Chryxus willemsei Chen, Hartong & Cai, n. sp. was collected near Mapana Creek in the Commewijne District of Suriname. Comparing locations in Google Maps with original maps made by the collector J. P. Schulz (Centraal Bureau Luchtkaartering 1959; Schulz 1971) and other publications (Schulz 1960; Fernandes & van Doesburg 2000), a point 5°18’17.7”N, 54°50’59.6”W (5.2650308, -55.0279351 or 5.3, -55.0) was selected. An accuracy radius of 20 km from this point is recommended. COMPARATIVE NOTES Among the three known species of Chryxus, Chryxus willemsei Chen, Hartong & Cai, n. sp. is most similar to C. garcetebarretti Gil-Santana, Leavengood, Bérenger, Martins & Oliveira, 2022 (from Paraguay), but can be separated from the latter by the following morphological character states: antennal pedicel uniformly yellowish brown (vs pale brown with darkened apex in C. garcetebarretti); median longitudinal sulcus on posterior pronotal lobe wide at anterior portion, gradually narrowed posteriorly (vs uniformly narrow in C. garcetebarretti); apex of scutellum clearly curved upwards (vs horizontal in C. garcetebarretti); femora without median dark marking (vs femora largely darkened at midlength in C. garcetebarretti); membrane of hemelytron with three clear whitish patches (vs with two faint whitish patches in C. garcetebarretti). Since the male of C. garcetebarretti is currently undiscovered, the differences on the male genitalia between these two species remain unknown. Chryxus willemsei Chen, Hartong & Cai, n. sp. also resembles C. bahianus Gil-Santana, Costa & Marques, 2007 (from Brazil), but it has a much larger body size, and the color patterns on legs and hemelytron are very different between these two species. The lateral margins of the abdomen are simple in shape in C. willemsei Chen, Hartong & Cai, n. sp., but in C. bahianus the posterolateral angles of the segments II-V are distinctly prominent. Moreover, the paramere of this new species has one large, peculiar-shaped process on its inner surface, with one short and one long branches, while C. bahianus only has one small, subquadrate, lamelliform process at the same position.

Authors 4

1. Z. Q. Chen

   China Agricultural University

   Affiliation as printed

   State Key Laboratory of Agricultural and Forestry Biosecurity, MARA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193 (China)

2. Charlotte Hartong Aachen Department of Entomology, Naturalis Biodiversity Centre

   Naturalis Biodiversity Center

   Affiliation as printed

   Department of Entomology, Naturalis Biodiversity Center, Darwinweg 2, 2333 CR, Leiden (The Netherlands)

3. Hu Li

   China Agricultural University

   Affiliation as printed

   State Key Laboratory of Agricultural and Forestry Biosecurity, MARA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193 (China)

4. Wanzhi Cai

   China Agricultural University

   Affiliation as printed

   State Key Laboratory of Agricultural and Forestry Biosecurity, MARA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193 (China) caiwz @ cau. edu. cn (Wanzhi Cai, corresponding author)