Megacormus, Karsch, 1881

Teruel, Rolando, Kovařík, František, Lowe, Graeme & Šťáhlavský, František, 2023, Two new species of the remarkable scorpion genus Megacormus Karsch, 1881 (Scorpiones: Euscorpiidae), Euscorpius 375, pp. 1-22 : 16-17

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

– 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.

Figures

Figures 27–34: Megacormus seductus sp. n. Figures 27–28. Male holotype, carapace and tergites I–IV (27) and coxosternal area and sternites (28). Figures 29–34. Female paratype, carapace and tergites I–IV (29), coxosternal area and sternites (30), and left legs I–IV, retrolateral aspect (31–34).

Figures 35–42. Megacormus seductus sp. n. Figures 35, 37–39. Male holotype, telson in lateral (35), metasoma and telson in lateral (37), dorsal (38) and ventral (39) views. Figures 36, 40–42. Female paratype, telson in lateral (36), metasoma and telson in lateral (40), dorsal (41) and ventral (42) views. Scale bars: 10 mm (37–39, 40–42).