Chaerilobuthus hansgeorgmuelleri Lourenço, 2019

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), Zoological Journal of the Linnean Society 203 (1), pp. 1-60 : 31-34

Chaerilobuthus hansgeorgmuelleri Lourenço, 2019

( Figs 25–26 , 39 )

Chaerilobuthus hansgeorgmuelleri Lourenço, 2019 in Lourenço and Velten, 2019: 2–10, figs 1–8.

Type material: Holotype: one juv. ♀ (personal collection of Hans-Georg Müller, Gelsenkirchen, Germany), Cretaceous (Cenomanian) burmite: MYANMAR: Kachin State (precise locality unknown).

Diagnosis: Thefollowingcombinationofcharactersisdiagnosticfor C. hansgeorgmuelleri : carapace length less than posterior width ( Fig. 26A ); carapace anterior margin slightly depressed submedially ( Fig. 26A ); lateral ocelli protruding ( Fig. 26A ); sternum relatively wide ( Fig. 26B ); pectines each with five teeth ( Fig. 26B ); pedipalp patella trichobothrium i aligned with trichobothrium d 3 ( Fig.26F ); pedipalp chela robust, manus globose, ratio of chela length: chela manus width less than 3 ( Fig. 26C ).

Description: Based on the material examined ( NIGP 201164).

Carapace: Length less than posterior width (L/ PW = 0.94). Anteromedian depression narrow, shallow; anterosubmedial depressions absent; lateral ocular carinae absent; posteromedian and posteromarginal sulci distinct; surfaces almost smooth to sparsely and finely granular ( Fig. 26A ). 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 25B , 39G ). Leg I maxillary lobes (coxapophyses) distal margins slightly curved, dilate anteriorly and adorned with serrula comprising c. 15–25 denticles ( Fig. 39G ). Sternum broad, pentagonal; lateral margins sublinear, parallel; ventral surface flat, without distinct concave region or median sulcus; posteromedian depression wide, shallow ( Fig. 26B ).

Chelicerae: Fixed finger and manus, prolateral and ventral surfaces each with numerous long, dense macrosetae ( Fig. 25A ). Cheliceral dentition not clearly visible.

Pedipalps: Segments moderately robust; surfaces sparsely covered by short microsetae ( Fig. 25A ). Femur with three carinae evident; dorsalsurfacewithseveralcoarsegranules;prodorsalandproventral carinae distinct, serrate; retrodorsal carinae distinct, smooth, and costate ( Fig. 26D ). Patella with five carinae evident; prodorsal carina distinct, costate-granular; prolateral surface, dorsoventral ‘vaulted’ projection (‘anterior process’) distinct with moderately developed pair of apophyses or tubercles (‘patellar spurs’), each possessing one macroseta; retrodorsal and retroventral carinae smooth, costate ( Figs 25B , 26F ). Chela relatively robust (CL/ CW = 2.62, Appendix 2); manus globose; chela with six carinae evident; digital carina complete, distinct; dorsomedian carina moderately distinct, costate at base of fixed finger to medially on manus, 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 25A, B , 26C ). Chela finger dentition not visible. Trichobothrial pattern Type D, β configuration. Femur with 11 trichobothria, five d, three i, and three e trichobothria; trichobothrium e 1 situated proximal to trichobothrium d 3; trichobothrium e 3 situated dorsal to trichobothrium d 6 ( Fig. 26D ). Patella with 10 trichobothria, including three d, one i, and two e trichobothria; trichobothrium i 1 aligned with trichobothrium d 3 ( Fig. 26F ). Chela with 12 trichobothria; fixed finger with two d, three i, and two e 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 ( Fig. 26C ).

Pectines: Basal piece not visble ( Fig. 26B ). Three marginal lamellae and four median lamellae; longitudinal suture between marginal and median lamellae distinct. Fulcra absent or obsolete. Teeth rounded, peg sensilla not visible.

Genital operculum: Two opercular sclerites narrow and completely separated ( Fig. 26B ).

Material examined: MYANMAR: Kachin State: Noije Bum near Hukawng Valley , precise locality unknown, Cretaceous (Cenomanian) burmite: one subad. (sex unknown), mesosoma and metasoma absent ( NIGP 201164 ) .

Figures

Figure 25. Chaerilobuthus hansgeorgmuelleri Lourenço, 2019, one subad. (NIGP 201164), habitus under incident light. A, dorsal aspect. B, ventral aspect. Scale bars: 1 mm.

Figure 26. Chaerilobuthus hansgeorgmuelleri Lourenço, 2019, one subad. (NIGP 201164), micro-CT reconstruction. A, B, E, carapace, dorsal, ventral, and frontal aspects.C, D, F, pedipalp trichobothrial pattern, chela, femur, and patella, dorsal, ventral, and lateral aspects.Scale bars: 1 mm (A, C, E, F); 500 μm (D).

Figure 39. Scorpion taxa illustrating presence or absence of serrula on maxillary lobes (coxapophyses) of legs I and II under confocal microscopy. A, Chaerilobuthus serratus Lourenço, 2016, one juv. (NIGP 200656).B, Chaerilobuthus enigmaticus Lourenço, 2015, one juv. (NIGP 201158). C, Chaerilobuthus enigmaticus Lourenço, 2015, one juv. (NIGP 201159).D, Chaerilobuthus complexus Lourenço, 2011, one juv. (NIGP 200655). E, Chaerilobuthus knodelorum Lourenço, 2018, one juv. (NIGP 200657).F, Chaerilobuthus gigantosternum Lourenço, 2016, one juv. (NIGP 200654).G, Chaerilobuthus hansgeorgmuelleri Lourenço, 2019, one subad.(NIGP 201164). H, Betaburmesebuthus bellus Lourenço 2016, one juv.(NIGP 200649). I, Chaerilus sp., one juv. (NIGP 180155). Scale bars: 100 μm (A–E, G–I); 50 μm (F).