Chaerilobuthus enigmaticus Lourenco 2015
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 enigmaticus

description: Chaerilobuthus enigmaticus Lourenço, 2015
(Figs 17–21, 39)
Chaerilobuthus enigmaticus Lourenço, 2015: 44–48, figs 1–6.
Type material: Holotype: one juv. ♀ (personal collection of Patrick Müller, Käshofen, Germany), Cretaceous (Cenomanian) burmite: MYANMAR: Kachin State (precise locality unknown).
Diagnosis: The following combination of characters is diagnostic for C. enigmaticus: carapace anteromedian margin slightly posterior to anterolateral margins (Figs 17A and 18D); lateral ocelli not protruding, macular (Figs 18D, 20A); pedipalp chela moderately robust, manus globose, ratio of chela length: chela manus width less than 4 (Figs 18A, B, 21A); pectines each with five teeth (Figs 18I, 20F, G); ratio of metasomal segment IV: V length greater than 2 (Figs 18A, B, 20H, I, L); metasomal segment V dorsosubmedian carinae slightly serrate (Fig. 20L); telson vesicle bulbous, aculeus very short and moderately curved (Figs 18G, J, K, 19).
Description: Based on the material examined (NIGP 201158, 201159).
Carapace: Posterior width less than length (L/PW = 1.16, Appendix 2). Anterior margin with few, short microsetae; anteromedian depression not visible; anterosubmedial depressions absent; lateral ocular carinae absent; posteromedian and posteromarginal sulci obsolete; surfaces almost smooth to sparsely and finely granular (Fig. 20A, B). Median ocular tubercle situated anteromedially; median ocelli absent; one pair of large posterolateral major lateral ocelli present.
Coxosternalregion: Surfacesmooth,sparselycoveredinmacrosetae (Figs 20E, 39B, C). Leg I maxillary lobes (coxapophyses) distal margins slightly curved, dilate anteriorly and adorned with serrula comprising c. 15 denticles (Fig. 39B, C). Sternum pentagonal; lateral margins sublinear, parallel; ventral surface flat, without distinct concave region or median sulcus; posteromedian depression wide, shallow (Figs 17A, 20E).
Chelicerae: Fixed finger and manus, prolateral and ventral surfaces each with numerous long, dense macrosetae (Fig. 18E, F). Cheliceral dentition partly visible, moveable finger with long dorsal distal (dd) denticle, small dorsal subdistal denticle, stout dorsal median denticle, long ventral distal (vd) denticle and four or five small ventral accessory (va) denticles; fixed finger with long distal denticle and small subdistal denticle (Figs 18E, F, 20C). Moveable finger with prominent serrula comprising long spinules in proximal three-quarters (Fig. 18F).
Pedipalps: Segments moderately robust; surfaces sparsely covered by short microsetae and few macrosetae (Figs 18A, B, 21A). Femur with four carinae evident; prodorsal and proventral carinae distinct, serrate; retrodorsal and retroventral carinae smooth, costate (Figs 18A, 21A, C). Patella with five carinae evident; prodorsal carina obsolete, comprising several tubercles; 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 18A, B, 21A, D). Chela relatively robust (CL/CW = 3.22 or 3.55, Appendix 2); manus globose; chela with six carinae evident; digital carina complete, distinct, granular medially, becoming costate proximally and distally; dorsomedian carina reduced to few granules at base of fixed finger, becoming obsolete proximally on manus; prodorsal carina distinct, comprising several prominent spiniform granules; promedian and proventral carinae obsolete, each comprising few isolated granules; retroventral carina obsolete; dorsal secondary, subdigital, retromedian and ventromedian carinae absent or obsolete (Figs 18A, B, 21A, B, E, F). Only fixed finger distal denticle subrows visible, oblique, slightly imbricate and separated by large serrate prolateral and retrolateral denticles (Fig. 21A). Trichobothrial pattern Type D, β configuration. Femur with three trichobothria visible: two d and one i trichobothria (Fig. 21C). Patella with six trichobothria visible, including three d, one i, and two e trichobothria; trichobothrium i 1 situated distal to trichobothrium d 3 (Fig. 21A, D). Chela with 10 trichobothria visible; fixed finger with two d and one i trichobothria; manus with four 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.
Legs: Tibia lateral and ventral surfaces each with scattered macrosetae (Fig. 18C, 20J, K). Basitarsi each with pair of spinule rows, comprising c. 10 relatively long spinules, distally. Telotarsi each with slightly irregular pair of ventrosubmedian spinule rows, comprising relatively long spinules. Ungues moderately long, distinctly curved; dactyl pronounced, pointed.
Pectines: Basal piece long, narrow (Fig. 20F). Three marginal lamellae and four median lamellae; surface sparsely covered in macrosetae; longitudinal suture between marginal and median lamellae distinct (Figs 18I, 20G). Fulcra absent or obsolete. Teeth rounded, distal three-quarters of each tooth occupied by sensillar field; peg sensilla very long, columnar (Fig. 20G).
Genital operculum: Two opercular sclerites narrow and completely separated, as long as pectinal plate; surfaces with several microsetae (Fig. 20E).
Mesosoma: Pretergites surfaces almost smooth (Fig. 19A); post-tergites I–VI surfaces finely granular, acarinate (Fig. 19A); tergite VII surface sparsely granular, with four slightly serrate carinae (paired dorsosubmedian and dorsolateral carinae) in posterior half of segment (Fig. 20H). Sternites surfaces smooth, with scattered macrosetae; posterior margins broadly recurved; respiratory spiracles small, ovoid, oblique (Figs 18H, 20D).
Metasoma: Segments I–V progressively increasing in length, I wider than long, others longer than wide (Fig. 18J, K, 20H, I, L). Segments I–V lateral and ventral surfaces each with few, short macrosetae (Fig. 18J, K, 20H, I, L); I–IV dorsal surfaces each with distinct depression (Figs. 18K, 20H). Segment I with six distinct carinae (paired dorsosubmedian, dorsolateral, and ventrolateral carinae), segments II–V each with eight distinct carinae (paired dorsosubmedian, dorsolateral, ventrolateral, and ventrosubmedian carinae); dorsosubmedian carinae distinct on all segments, markedly serrate on II–IV, moderately serrate, converging posteriorly on I and V; dorsolateral carinae distinct, moderately serrate on segments I, II and V, slightly serrate on III and IV; ventrolateral carinae distinct, moderately serrate on segments I–IV, markedly serrate on segment V; ventrosubmedian carinae absent on segment I, obsolete on II and III, distinct, moderately serrate on IV and V, and converging posteriorly on V (Fig. 18J, K, 20H, I, L).
Telson: Vesicle bulbous; dorsal surface flat; lateral and ventral surfaces relatively smooth with several macrosetae; (Figs 18G, 19A, B); subaculear tubercle absent; prominent subaculear setal pair, moderately long. Aculeus short, shallowly curved; base narrow, less than one-third vesicle width.
Material examined: MYANMAR: Kachin State: Noije Bum near HukawngValley,preciselocalityunknown, Cretaceous (Cenomanian) burmite: two juv. (sex unknown) (NIGP 201158, 201159).
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 21-26, DOI: 10.1093/zoolinnean/zlae169, http://zenodo.org/record/14831464