Two new species of the remarkable scorpion genus Megacormus Karsch, 1881 (Scorpiones: Euscorpiidae) Author Teruel, Rolando Author Kovařík, František Author Lowe, Graeme Author Šťáhlavský, František text Euscorpius 2023 375 1 22 journal article 10.5281/zenodo.8222206 1536-9307 8222206 E7C4D357-A2FF-4F8D-B93D-1B9B6CFE3115 Key to species of Megacormus 1. Adult male with basal lobe/notch combination of pedipalp fingers well-developed, absent in adult females and juveniles of both sexes (Figs. 44–45, 48–49, 58–59). ...................... 2 – Adult and juveniles of both sexes with basal lobe/notch combination of pedipalp fingers entirely absent (figs. 46– 47, 50–57). ...................................................................... 4 2. Pedipalp patella with 3 et trichobothria in distal external series; patella ventral surface granulose, with small to medium granules that are more sparse in the female ........ ................................................... M. grubbsi Sissom, 1994 – Pedipalp patella with 4 et trichobothria in distal external series; patella ventral surface smooth in female, smooth or almost smooth in male with only very fine, sparse granules (shagreened) in some areas ............................................ 3 3. Adult male pedipalp chela with dorsal marginal carina coarsely granulose, distal ventral surface of manus sparsely, finely granulose (figs. 59, 61 in KovařÍk, 2019: 15); metasoma V with dorsolateral carina only very slightly elevated (figs. 80, 83 in KovařÍk, 2019: 18) ......... .......................................... M. gertschi DÍaz Nájera, 1966 Figures 62 – 65 . Hemispermatophores of Megacormus spp . Figure 62 . M . orizaba sp . n . 19MD (holotype, No. 1621). Figure 63 . M . granosus (No. 2462) . Figures 64–65 . M . seductus sp . n . 22MA (holotype and paratopotype, Nos. 2460, 2461). Convex views of left hemispermatophores (62, 63) and right hemispermatophores shown in mirror image (64, 65). Scale bars: 500 μm. – Adult male pedipalp chela with dorsal marginal carina more finely granulose, distal ventral surface of manus densely, finely granulose (figs. 94, 96 in KovařÍk, 2019: 22); metasoma V with dorsolateral carina distinctly elevated (figs. 115, 118 in KovařÍk, 2019: 25). ................. ............................................................... M. orizaba sp . n . 4. Adult size medium for the genus, over 30 mm . Adult male pedipalp chelae robust and with intercarinal tegument glossy. .................................................................................... 5 – Adult size small for the genus, less than 30 mm . Adult male pedipalp chelae slender and with intercarinal tegument entirely matt. ................................................................... 6 5. Adult male with pedipalp manus and metasoma slenderer, metasomal segment V length/width ratio 2.60–2.80. ........ ................................................ M . franckei KovařÍk, 2019 – Adult male with pedipalp manus and metasoma more robust, metasomal segment V length/width ratio 1.94– 2.13. ................. M . xichu González-Santillán et al., 2017 6. Pectines with shaft not clearly divided into areas and lamellae, all fused together into a single triangular sclerite, at most with faint incomplete vestiges of sulci. Entire body and appendages densely covered by very short, rigid, white microsetae in addition to ordinary setae. ................. ............................................ M . granosus (Gervais, 1843) – Pectines with shaft clearly divided by deep sulci into well-defined areas and lamellae. Entire body and appendages either lacking or with only a few very short, rigid, white microsetae in addition to ordinary setae. ........................ 7 7. Adult male carapace with central median and posterior median carinae well-defined from surrounding granulation, finely granulose. Metasoma slenderer and with carinae stronger, composed of sharper granules. ........................... .......................................... M . segmentatus Pocock, 1900 – Adult male carapace with central median and posterior median carinae missing, not distinguishable from surrounding granulation ( Fig. 27 ). Metasoma more robust and with carinae weaker, composed of blunter granules ( Figs. 37–39 ). ..................................... M . seductus sp. n .