Betaburmesebuthus Lourenço, 2015

XUAN, QIANG, CAI, CHEN-YANG & HUANG, DI-YING, 2023, Revision of palaeoburmesebuthid scorpions in mid-Cretaceous amber from northern Myanmar (Scorpiones: Buthoidea), Palaeoentomology 6 (1), pp. 64-101 : 65-72

Genus Betaburmesebuthus Lourenço, 2015

Type species. Betaburmesebuthus kobberti Lourenço, 2015 (in Lourenço & Beigel, 2015).

Included species. Betaburmesebuthus kobberti ( Lourenço & Beigel, 2015) , B. muelleri ( Lourenço, 2015a) , B. bidentatus ( Lourenço, 2015a) , B. bellus (Lourenço, 2016) , B. fleissneri ( Lourenço & Velten, 2016a) , B. larafleissnerae ( Lourenço & Velten, 2016b) , B. joergi ( Lourenço & Rossi, 2017) , B. spinipedis ( Xuan, Cai & Huang, 2022) , B. villosus sp. nov., B. fuscus sp. nov., B. pohli ( Lourenço & Velten, 2017) comb. nov. and B. knodelorum ( Lourenço, 2021) comb. nov.

Diagnosis (emended). Five pairs of lateral ocelli present, including three major lateral ocelli (ALMa, MLMa, PLMa) and two minor lateral ocelli (PDMi, ADMi) ( Figs 2B , 6B , 10B , 17B , 20C , 25A , 28C ).Anterior margin of carapace with a wide weakly to strongly marked median concavity ( Figs 2A , 6A , 10A , 14A , 17A , 20A , 24A , 29A ); central median, posterior median and posterior marginal furrows of carapace well-marked in adults ( Figs 13A , 28A , 29A ). Median ocular tubercle well-marked and located on the first anterior third to the first anterior of carapace ( Figs 2A , 6A , 10A , 13A , 17A , 20A , 24A , 29A ). Sternum elongated pentagonal ( Figs 2D , 6E , 20F , 24C ). Pectines with 13–20 teeth and fulcra present ( Figs 2K , 10F , 24D , 29B ). Metasomal ventral carinae parallel ( Figs 5D , 13C, J , 30 E ). Telson with a very long aculeus and a tiny subaculear tubercle ( Figs 6I , 10H , 14B , 17G , 20I , 25J ). Trichobothriotaxic pattern Type A with beta - configuration ( Figs 3 , 7 , 11 , 14C, D , 18 , 21 , 26 ). Pedipalp patellar dorsomedian carina (DMc) well-developed ( Figs 3E , 7D , 11A , 15A , 18D , 21D , 23E , 29D ). Pedipalp finger dentition composed of about ten discrete linear rows of granules; each slightly oblique with proximal ends directed externally, rows slightly imbricated; a smaller spinous external accessory granule and a bigger spinous internal accessory granule present along the base of each denticle row; tip hooked ( Figs 2G, H , 6H , 13F, I , 21A–C ). Tibial spurs present on legs III and IV ( Figs 2I, J , 6J, K , 10K, L , 13G, H , 20J, K , 29F, H ). Telotarsus with few ventrosubmedian setae and a ventromedian spinules row ( Figs 2M, N , 6L, M , 10I, J , 17C , 20L, M ) or numerous ventrosubmedian setae ( Figs 14E–G , 15C–F , 23F , 24I , 25H, I , 29F–I ) .

Remarks. Previous descriptions of Betaburmesebuthus indicated that most members of the genus, except for B. bidentatus , bear three lateral ocelli ( Lourenço & Beigel, 2015; Lourenço, 2015a, 2016; Lourenço & Velten, 2016a, b; Lourenço & Rossi, 2017). Nonetheless, we confirm the presence of five pairs of lateral ocelli in B. spinipedis ( Xuan et al., 2022) . We do not regard this as a new feature since the fourth and fifth pairs of minor lateral ocelli are greatly reduced in size and are likely to be ignored by previous authors. Our examination of studied specimens reveals that B. bellus , B. kobberti , B. fleissneri , B. larafleissnerae , and B. muelleri share this character.

Lourenço & Velten (2017) reported another fossil from Burmese amber, which is assigned to a new genus and species, i. e., Spinoburmesebuthus pohli . Recently, Lourenço (2021) recorded the second species of this genus, S. knodelorum . The most important character of Spinoburmesebuthus claimed by Lourenço (2021) is the presence of subaculear tubercle. However, in another paper Lourenço presented a line-drawing of the adult male metasoma of Palaeoburmesebuthus knodeli ( Lourenço, 2018: fig. 4) which clearly shows a subaculear tubercle. In addition, a small subaculear tubercle also found in the juvenile individual of B. spinipedis ( Xuan, Cai & Huang, 2022) . Thus, this feature become a contradictory identification key, and we examined the additional materials of Betaburmesebuthus in this paper to contribute to the solution of this taxonomic confusion. We conclude that the subaculear tubercle is present in Betaburmesebuthus , which is difficult to discover in immature individuals but distinct in adult individuals. The two species assigned to alleged Spinoburmesebuthus show many similarities with Betaburmesebuthus and are the large specimens, as our materials, B. fuscus sp. nov. (NIGP200653) and B. sp. (NIGP201157), which all exhibit the obvious subaculear tubercle. As a result, we here merge the genus Spinoburmesebuthus into Betaburmesebuthus syn. nov. and transfer the two species of Spinoburmesebuthus to Betaburmesebuthus , i. e., B. pohli comb. nov. and B. knodelorum comb. nov.

The description of denticles of pedipalp fingers for Betaburmesebuthus remains ambiguous, which could be attributed to the fact that the original authors observed this structure only from the lateral view ( Lourenço, 2021: fig. 16). We provide clear fluorescence and confocal photos from the frontal view and suggest that the absence of any conspicuous accessory granules are artifacts. Remarkably, another Burmese amber fossil, Archaeoananteroides maderai ( Lourenço & Velten, 2016c) shows the same state in denticle rows with our studied specimens and this species is likely to be a member of Betaburmesebuthus .

Santiago-Blay et al. (2022) indicated that the tibial spurs III and IV are variable in Betaburmesebuthus (present in three species, absent or reduced in other three species). A detailed examination of our material, however, revealed the presence of tibial spurs III and IV is fixed in members of Betaburmesebuthus . We suggest that such an absent or reduced condition were probably due to the poor preservation or are artifacts of observation. Furthermore, the tibial spurs of immature individuals are usually undeveloped and not easily to identify.

Another interesting character is telotarsus armature. After the examination of all material, we observed two types: few ventrosubmedian setae and a ventromedian spinules row versus numerous ventrosubmedian setae. The feature is rarely mentioned in published papers and should be regarded as a diagnostic character, despite that the telotarsus armature was considered an important taxonomic character in extant scorpion at higher-level taxa ( Soleglad & Fet, 2003). Lacking more distinct diagnostic characters, we refrain from establishing a new genus to divide the two forms.

Figures

FIGURE 2. Details of Betaburmesebuthus bellus, NIGP200648, under confocal microscopy with depth color-coding. A, Carapace. B, Lateral ocelli. C, Coxapophysis, coxa and trochanter of leg I. D, Sternum and genital operculum. E, Spiracle of sternite VI. F, Tergites I–VI. G, Dentition of movable finger. H, Dentition of fixed finger. I, Tibial spur of leg III. J, Tibial spur of leg IV. K, Left pectine. L–O, Telotarsi of legs I–IV.Abbreviations:ADMi, anterodorsal minor ocellus; ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus; sp, spiracle; ts, tibial spur. Scale bars = 200 μm in A, F, G, K; 100 μm in C, D, E, H, I, J, L, M, N, O; 50 μm in B.

FIGURE 3. Trichobothrial pattern of Betaburmesebuthus bellus, NIGP200648, under confocal microscopy (B, C, E, F, H–K) and green epifluorescence (A, D, G). A, B, Left femur, dorsal view. C, Right femur, dorsal view. D, E, left patella, dorsal view. F, Right patella, dorsal view. G, Left chela, dorsal view. H, Left fixed finger, dorsal view. I, Right manus, ventral view. J, Left manus, dorsal view. K, Left manus, ventral view. Scale bars = 200 μm.

FIGURE 5. Details of Betaburmesebuthus bellus, NIGP200649, under green epifluorescence. A, Carapace and tergites. B, Coxosternal region, pectines and sternites. C, Metasomal segments I–IV, ventral view. D, Metasomal segments I–IV, dorsal view. E, Metasomal segment V and telson, lateral view. F, Tibial spur of leg III. G, Tibial spur of leg IV. H, Telotarsus of leg III. I, Telotarsus of leg IV. Abbreviations: ts, tibial spur. Scale bars = 400 μm in A–E; 100 μm in F–I.

FIGURE 6. Details of Betaburmesebuthus bellus, NIGP200649, under confocal microscopy. A, Carapace. B, Lateral ocelli. C, Chelicerae, dorsal view. D, Chelicerae, ventral view. E, Coxosternal region. F, Genital operculum and basal piece. G, Spiracles. H, Dentition of movable finger. I, Telson. J, Tibial spur of leg III. K, Tibial spur of leg IV. L, Telotarsi of leg IV. M, Telotarsi of leg III. Abbreviations:ADMi, anterodorsal minor ocellus; ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus; sp, spiracle; st, subaculear tubercle; ts, tibial spur. Scale bars = 200 μm in A, E, G, H; 100 μm in C, D, F, I, J, K, L, M; 50 μm in B.

FIGURE 7. Trichobothrial pattern of Betaburmesebuthus bellus, NIGP200649, under confocal microscopy (B, D, F, G) and green epifluorescence (A, C, E). A–B, Right femur, dorsal view. C–D, Right patella, dorsal view. E–F, Right chela, dorsal view. G, Right manus, ventral view. Scale bars = 200 μm in A, B, C, D, G; 400 μm in E, F.

FIGURE 10. Details of Betaburmesebuthus kobberti, NIGP200650, under confocal microscopy. A, Carapace. B, Lateral ocelli. C, Coxapophyses I–II. D, Tergites I–VI. E, Sternites IV–VII. F, Pectine. G, Tergite VII and Metasomal segments I–II. H, Telson. I, Tibial spur of leg II. J, Tibial spur of leg IV. K, Telotarsi of leg III. L, Telotarsi of leg IV. Abbreviations: ADMi, anterodorsal minor ocellus; ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus; sp, spiracle; st, subaculear tubercle; ts, tibial spur. Scale bars = 200 μm in A, D, E, F, G, H; 100 μm in C, I, J, K, L; 50 μm in B.

FIGURE 11. Trichobothrial pattern of Betaburmesebuthus kobberti, NIGP200650, under confocal microscopy. A, Left femur, patella and chela, dorsal view. B, Left femur, patella and chela, ventral view. C. Left femur and fixed finger, dorsal view. D, Right fixed finger, dorsal view. E, Right chela, dorsal view. Scale bars = 200 μm.

FIGURE 13. Details of Betaburmesebuthus fleissneri, NIGP201154, under incident light. A, Carapace and tergites I–III. B, Coxosternal region, pectines and sternites. C, J, Metasoma and telson, lateral view. D, Tergites IV–VII. E, Left pedipalp, dorsal view. F, Dentition of left chela movable finger. G, Tibial spur of leg IV. H, Tibial spur of leg III. I, Dentition of right chela finger. Abbreviations: ts, tibial spur. Scale bars = 2 mm in C, J; 1 mm in A, B, D, E; 500 μm in F, G, H, I.

FIGURE 14. Details of Betaburmesebuthus fleissneri, NIGP201154, under green epifluorescence. A, Carapace and chelicerae. B, Telson, lateral view. C, Patella, dorsal view. D, Femur, dorsal view. E, Telotarsus of leg IV. F, Telotarsus of leg II. G, Telotarsus of leg III. Abbreviations: st, subaculear tubercle. Scale bars = 400 μm.

FIGURE 15. General habitus and details of Betaburmesebuthus sp., NIGP201157, under incident light. A, Ventral view. B, Dorsal view. C, Tarsus of right leg I. D, Tarsus of right leg II. E, Tarsus of right leg III. F, Tarsus of left leg III.Abbreviations: st, subaculear tubercle. Scale bars = 5 mm in A, B; 1 mm in G; 500 μm in C, D, E, F.

FIGURE 17. Details of Betaburmesebuthus larafleissnerae, NIGP201155, A, C–G under green epifluorescence; B under confocal microscopy; H, I under incident light. A, Carapace and chelicerae, dorsal view. B, Lateral ocelli. C, Tarsus of right leg III. D, Tergites. E, Metasomal segments I–IV and telson, lateral view. F, Metasomal segments I–III, ventral view. G, Metasomal segments IV–V and telson, lateral view. H, Pectines. I, Sternite V with right spiracle. Abbreviations: ADMi, anterodorsal minor ocellus; ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus; sp, spiracle; st, subaculear tubercle; ts, tibial spur. Scale bars = 400 μm in A, D, E, F, G, H; 200 μm in C, I; 50 μm in B.

FIGURE 18. Trichobothrial pattern of Betaburmesebuthus larafleissnerae, NIGP201155, A, C, E, F under green epifluorescence; B, D under confocal microscopy. A, B, Right femur, dorsal view. C, D, Left patella, dorsal view. E. Left femur, dorsal view. F, Left chela, dorsal view. Scale bars = 200 μm.

FIGURE 20. Details of Betaburmesebuthus muelleri NIGP201156, A, D, E, F under green epifluorescence; B, C, F, G, I–M under confocal microscopy. A, Carapace and tergites. B, Chelicerae, dorsal view. C, Lateral ocelli. D, Tergite VII and metasomal segments I–IV, dorsal view. E, Coxosternal region, pectines and sternites. F, Sternum and genital operculum. G, Pectine. H, Tergite VII and metasomal segments I–IV, ventral view. I, Telson. J, Tibial spur of leg III. K, Tibial spur of leg IV. L, Tarsus of leg I. M, Tarsus of leg IV.Abbreviations:ADMi, anterodorsal minor ocellus; sp, spiracle; st, subaculear tubercle; ts, tibial spur. Scale bars = 400 μm in A, D, E, H; 100 μm in B, F, G, I–M; 50 μm in C.

FIGURE 21. Trichobothrial pattern of Betaburmesebuthus muelleri NIGP201156, A, B under green epifluorescence; C, D under confocal microscopy. A, Left pedipalp, dorsal view. B, Left pedipalp, ventral view. C–D, Left chela, dorsal view. E. Left femur and patella, dorsal view. Scale bars = 400 μm.

FIGURE 23. Details of Betaburmesebuthus villosus sp. nov., holotype, NIGP200652, under incident light. A, Tergites. B, Sternum and genital operculum and pectines. C, Chela, dorsal view. D, Femur, dorsal view. E, Patella, dorsal view. F, Right Leg III. G, Tergite VII and metasomal segments I–II. H, Telson. Abbreviations: ts, tibial spur. Scale bars = 1 mm in A; 500 μm in B–H.

FIGURE 24. Details of Betaburmesebuthus villosus sp. nov., holotype, NIGP200652, under green epifluorescence. A, Carapace. B, tergites. C, Sternum and genital operculum. D, Pectines. E, Tergite IV–VI. F, Femur, dorsal view. G, Patella, dorsal view. H, Metasomal segments III–IV, Lateral view. I, Left leg III. J, Right chela. Scale bars = 400 μm in A, B, D–H, J; 200 μm in C, I.

FIGURE 25. Details of Betaburmesebuthus villosus sp. nov., holotype, NIGP200652, under confocal microscopy. A, Lateral ocelli. B, Femur, dorsal view. C, Spiracle. D, Tibial spur of leg III. E, Tibial spur of leg IV. F, Right chela manus, ventral view. G, Left chela manus, ventral view. H, Tarsus of leg III. I, Tarsus of leg IV. J–K, Telson, lateral view. Abbreviations: ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus; st, subaculear tubercle; ts, tibial spur. Scale bars = 100 μm in A–C, K; 200 μm in D–J.

FIGURE 26. Line drawings of the trichobothrial pattern of Betaburmesebuthus villosus sp. nov., holotype, NIGP200652. A, femur; B, patella; C, chela. Scale bars = 200 μm.

FIGURE 28. Micro-CT reconstruction of Betaburmesebuthus fuscus sp. nov., holotype, NIGP200653. A, Dorsal view. B, Ventral view. C, Lateral ocelli.Abbreviations:ADMi, anterodorsal minor ocellus; ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus. Scale bars = 3 mm in A, B; 500 μm in C.

FIGURE 29. Details of Betaburmesebuthus fuscus sp. nov., holotype, NIGP200653, under incident light. A, Left pedipalp and carapace. B, Pectines. C, Sternites VI–VII and metasomal segments I–III. D, Femur, dorsal view. E, Patella, dorsal view. F, Tarsus of leg IV. G, Tarsus of leg I. H, Tarsus of leg III. I, Tarsus of leg II. J, Spiracle.Abbreviations: sp, spiracle; ts, tibial spur. Scale bars = 1 mm in A, C; 500 μm in B, F–J; 400 μm in D, E.

FIGURE 30. Micro-CT reconstruction details of Betaburmesebuthus fuscus sp. nov., holotype, NIGP200653. A, B, Left pedipalp. C–E, Metasomal segments I–III. Scale bars = 1.5 mm in A, B; 1 mm in C–E.