Chaerilobuthus complexus Lourenco and Beigel 2011
Creators: name: Xuan, Qiang
name: Prendini, Lorenzo
name: Engel, Michael S.
name: Cai, Chenyang
name: Huang, Diying
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Scorpiones
Chaerilobuthidae
Chaerilobuthus
Chaerilobuthus complexus

description: Chaerilobuthus complexus Lourenço and Beigel, 2011
(Figs 11–16, 39)
Chaerilobuthus complexus Lourenço and Beigel, 2011: 635–639, figs 1–11.
Type material: Holotype: 1 juv. (sex unknown) (Senckenberg Museum, Frankfurt, Germany), Cretaceous (Cenomanian) burmite: MYANMAR: Kachin State (precise locality unknown).
Diagnosis: The following combination of characters is diagnostic for Chaerilobuthus complexus: carapace anteromedian margin aligned with anterolateral margins (Figs 11A, 14A); carapace anterior margin slightly depressed submedially (Figs 12A, 15A); lateral ocelli protruding (Figs 12A, 15A); sternum relatively narrow (Figs 17B, 20B); pedipalp chela robust, ratio of chela length: chela manus width less than 5 (Figs 13C, 16); pedipalp chela fixed finger median denticle row comprising c. seven oblique subrows (Figs 13C, 15E); pectines each with five teeth (Figs 12B, 15D); mesosoma relatively wide, tergite VII width much greater than length (Fig 11E); metasomal segment I width much greater than length (Fig. 12I, J).
Description: Based on the material examined (NIGP 200655, 201160).
Carapace: Anterior carapace margin with few, short microsetae; anteromedian depression narrow, shallow; anterosubmedial depressions absent; lateral ocular carinae absent; posteromedian and posteromarginal sulci obsolete; surfaces almost smooth to sparsely covered in microsetae (Figs 12A, 15A). Median ocular tubercle situated anteromedially; median ocelli absent; one pair of large posterolateral major lateral ocelli present.
Coxosternal region: Surface smooth, sparsely covered in macrosetae (Figs 12B, 39D). Leg I maxillary lobes (coxapophyses) distal margins slightly curved, dilate anteriorly and adorned with serrula comprising c. 14–16 spinules (Fig. 39D). Sternum pentagonal; lateral margins sublinear, parallel; ventral surface flat, without distinct concave region or median sulcus; posteromedian depression wide, shallow; posterior margin slightly recurved (Figs 12B, 15B).
Chelicerae: Fixed finger and manus, prolateral and ventral surfaces each with numerous long, dense macrosetae (Fig. 12C, G). Moveable finger markedly overlapping fixed finger (Fig. 12D) such that cheliceral dentition partly visible; moveable finger with long dorsal distal (dd) denticle, small dorsal subdistal denticle, stout dorsal median denticle and long ventral distal (vd) denticle; fixed finger with long distal denticle and small subdistal denticle (Figs 18E, F, 20C). Moveable finger with prominent serrula, comprising moderately long spinules in proximal three-quarters (Fig. 12C, G).
Pedipalps: Segments moderately robust; surfaces sparsely covered by short microsetae and few macrosetae (Figs 11, 13, 14, 16). Femur with three carinae evident; prodorsal and proventral carinae distinct, serrate, prodorsal carinae with small apophysis proximally (Figs 13A, 15F). Patella with four carinae evident; prolateral surface, dorsoventral ‘vaulted’ projection (‘anterior process’) distinct with prominent pair of apophyses or tubercles (‘patellar spurs’), each possessing one macroseta; retrodorsal and retroventral carinae smooth, costate (Figs 13B, 15I). Chela relatively robust; manus globose; chela with six carinae evident; digital carina incomplete, distinct on fixed finger, obsolete on manus; dorsomedian carina reduced to few granules proximally on manus; prodorsal carina distinct, comprising several strong spiniform granules; promedian and proventral carinae obsolete, each comprising few isolated granules; retroventral carina obsolete, smooth, and costate (Figs 13C, D, 15H); dorsal secondary, subdigital, retromedian and ventromedian carinae absent or obsolete. Fixed and moveable fingers median denticle rows each comprising seven oblique, slightly imbricate subrows, separated by large serrate prolateral and retrolateral denticles (Figs 13C, 15E). Trichobothrial pattern Type D, β configuration. Pedipalp femur with 10 trichobothria visible, five d, two i, and three e trichobothria, trichobothria d 1, d 2, d 4, and d 6 noticeably smaller than others (‘petite’); trichobothrium e 1 situated proximal to trichobothrium d 3; trichobothrium e 3 vertically aligned with trichobothrium d 6 (Figs 13A, 16). Patella with four trichobothria visible, including three d and one i trichobothria; trichobothrium i 1 situated distal to trichobothrium d 3 (Figs 13B, 16). Chela with eight trichobothria visible; fixed finger with two d, two e and one i trichobothria; manus with two E and one V trichobothria; trichobothrium Et 1 situated distally on manus, almost aligned with or proximal to moveable finger condyle; trichobothrium eb situated on fixed finger, slightly distal to moveable finger condyle; trichobothrium esb situated medially on fixed finger; trichobothrium V 2 situated distally on manus and near retroventral carina (Figs 13C, D, 16).
Legs: Tibia lateral and ventral surfaces each with scattered macrosetae (Figs 12K, L, 15G). Basitarsi each with pair of spinule rows, comprising seven or eight relatively long spinules, distally (Figs 12H, L, 15G). Ungues moderately long, distinctly curved; dactyl pronounced, pointed (Figs 12K, L, 15G).
Pectines: Basal piece long, narrow (Figs 12B, 15D). Three marginal lamellae and four median lamellae; surface sparsely covered in macrosetae; longitudinal suture between marginal and median lamellae distinct. Fulcra absent or obsolete. Teeth rounded, distal half of each tooth occupied by sensilla field; peg sensilla very long, columnar with distinct pore.
Genital operculum: Two opercular sclerites narrow and completely separated, as long as pectinal plate (Fig. 12B).
Mesosoma: Pretergites surfaces almost smooth (Fig. 12E); post-tergites I– VI surfaces finely granular, acarinate (Fig. 12E); tergite VII surface sparsely granular with four moderately developed carinae (paired dorsosubmedian and dorsolateral carinae) in posterior half of segment (Fig. 11A). Sternites surfaces smooth, with scattered macrosetae; posterior margins broadly recurved; respiratory spiracles (stigmata) small, ovoid, oblique (Figs 12F, 15C).
Metasoma: Segments I– III progressively increasing in length, I wider than long, others longer than wide (Fig. 12I, J). Segments I– III lateral and ventral surfaces each with few, short macrosetae; dorsal surfaces each with distinct depression. Segments I– III each with six distinct carinae (paired dorsosubmedian, dorsolateral and ventrolateral carinae); dorsosubmedian carinae distinct, markedly serrate; dorsolateral carinae distinct, moderately serrate; ventrolateral carinae obsolete on segment I, moderately developed on II and III.
Material examined: MYANMAR: Kachin State: Noije Bum near Hukawng Valley, precise locality unknown, Cretaceous (Cenomanian) burmite: one juv. (sex unknown), mesosomal segments IV, V and telson absent (NIGP 200655), one juv. (sex unknown), sinistral pedipalp absent (NIGP 201160).
description: Published as part of Xuan, Qiang, Prendini, Lorenzo, Engel, Michael S., Cai, Chenyang & Huang, Diying, 2025, Extinct scorpion family Chaerilobuthidae from Mid-Cretaceous Burmese amber reinterpreted as subfamily of extant family Pseudochactidae (Chelicerata: Scorpiones), pp. 1-60 in Zoological Journal of the Linnean Society 203 (1) on pages 13-20, DOI: 10.1093/zoolinnean/zlae169, http://zenodo.org/record/14831464