Betaburmesebuthus fuscus, XUAN & CAI & HUANG, 2023

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 : 96-100

Betaburmesebuthus fuscus sp. nov.

( Figs 27–30 )

Zoobank LSID urn:lsid:zoobank.org:act:4788832D-992B-4A9A-BD43-E94C48BFC7DA

Material. NIGP201154 , one probable adult male, metasoma IV and V, telson and part of right pedipalp missing.

Etymology. The species is named after the color of scorpion body; the Latin ‘ fuscus ’, meaning dark brown. The name masculine in gender.

Diagnosis(emended). Thisnewspeciescanbeclearly distinguished from other Betaburmesebuthus species by the following set of characters:1) general integument color dark brown 2) anterior margin of carapace with a single moderate marked median concavity ( Figs 28A , 29A ); 3) spiracles small, oblique and slit ( Fig. 29J ); 4) pectines with 20 teeth ( Fig. 29B ); 5) dorsal patellar spur carina with four strong tubercles ( Fig. 29D ); 6) Chela manus with one small tubercle on internal surface ( Fig. 30 ); and 7) telotarsus covered by numerous ventrosubmedian setae ( Fig. 29F–I ).

Locality and horizon. Noije Bum near Tanai, Hukawng Valley, Kachin State of northern Myanmar; upper Albian to lower Cenomanian (mid-Cretaceous).

Description. Carapace. Covered by coarse granules without distinct carinae, posterior and posterior median furrows evident ( Figs 28A , 29A ); median eyes oval, large sized and separated by one ocular diameter ( Fig. 29A ); PDMi posterodorsal to PLMa, and ADMi posterior to PLMa ( Fig. 28C ).

Coxosternal region. A deep groove observed between coxapophysis I and coxa I ( Fig. 28B ); genital operculum longitudinally divided and composed of two oval valves ( Fig. 28B ).

Chelicerae. With setae on internal surface ( Fig. 29A ); cheliceral dentition not visible except a long dorsal distal (dd) denticle ( Fig. 29A ).

Pedipalps.Femur with five carinae( Figs29E , 30A, B ): internomedian carina well-marked and serratocrenulate; dorsointernal carina costate; dorsoexternal, ventroexternal and ventrointernal carinae crenulate. Patella with seven carinae ( Figs 29D , 30A, B ): Dorsal Patellar Spur carina (DPSc) and Ventral Patellar Spur carina (VPSc) welldeveloped; dorsointernal, dorsomedian and ventrointernal carinae costate with several granules; ventroexternal and dorsoexternal carinae smooth and costate; two evident macrosetae present on distal. Chela relatively slender (Cl/ Cw = 6.74, Table 1 ); finger denticle rows not visible.

Trichobothrial pattern ( Fig. 29D, E ). Trichobothria not clear. Femur with 7 trichobothria observed, 5 dorsal and 2 external trichobothria, trichobothrium e 1 proximal to trichobothrium d 5. Patella with 4 trichobothria observed, including 1 dorsal and 3 external trichobothria.

Legs. Trochanter bearing a lateral apophysis ( Fig. 28B ); femur with serrated internal and external carinae evident ( Fig. 27B ); patella incrassate with serrated internal carina ( Fig. 27B ). Prolateral and retrolateral pedal spurs present on all legs ( Fig. 29F–I ). Ungues very long, dactyl pointed ( Fig. 29F–I ).

Pectines ( Fig. 29B ). Basal piece with an anterior median furrow evident ( Fig. 28B ). Pectines with 3 marginal lamellae and 10 median lamellae; fulcra present, small. Numerous sensory hairs extending from surface of lamellae. Peg sensillae very short and sensory area fully occupied distal end of teeth.

Mesosoma. Tergites covered by coarse granules ( Fig. 27A ), median carina evident on posterior half of all tergites ( Fig. 28A ); dorsolateral carinae evident on tergites III and VI ( Fig. 28A ); tergite VII with five costate carinae ( Fig. 28A ): paired dorsolateral and lateral carinae, and one axial carina on anterior half. Sternites covered by coarse granules; Sternite VII with five carinae ( Fig. 29C ).

Metasoma ( Figs 29C , 30C–E ). All segments longer than width and covered by macrosetae ventrally. Segments I–III with distinct depression dorsally; segments I–II with ten carinae (paired ventromedian, ventrolateral, lateral, dorsolateral, and dorsal carinae); segments III with eight well marked carinae (paired ventromedian, ventrolateral, dorsolateral, and dorsal carinae) and two feebly marked lateral carinae; all ventral and dorsal carinae obviously serrated.

Remarks. The most distinguishing character differentiating B. fuscus from others is the general body coloration and other species all exhibit yellowish integument. In addition, the slit-like spiracle is shared by B. larafleissnerae and B. villosus sp. nov. but not oblique in them.

Figures

FIGURE 27. General habitus of Betaburmesebuthus fuscus sp. nov., holotype, NIGP200653, under incident light. A, Dorsal view. B, Ventral view. Scale bars = 2 mm.

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.