Chactidae (Soleglad & Fet, 2003)

Soleglad, Michael E. & Fet, Victor, 2005, The genus Auyantepuia González-Sponga, 1978 is confirmed as a synonym of Broteochactas Pocock, 1893 (Scorpiones: Chactidae), Euscorpius 29 (29), pp. 1-14 : 4

Current Chactidae systematics

With respect to trichobothrial patterns, the clade Euscorpiidae + Chactidae is distinguished (i.e., synapomorphies) by the placement of chelal trichobothrium it on the palm and the dorsal (= outer) angling of the est– esb–eb juncture (i.e., eb situated close to finger inner edge). The latter synapomorphy is of particular relevance to this discussion since it is key, in part, in differentiating the two subtribes of brotheine tribe Brotheini . Figure 1 shows the arrangement of the eb–et series of the chelal finger illustrating representative species spanning families Euscorpiidae and Chactidae . As can be seen from the illustrated examples, the est–esb–eb juncture forms essentially a right to obtuse angle, trichobothrium eb positioned the closest to the fixed finger’s inner edge. In the euscorpiids the eb–et series is situated more distally on the fixed finger, while eb, although close to the inner finger edge, is not adjacent to the fixed/movable finger juncture. In the three subfamilies of Chactidae , however, eb is adjacent to the fixed/movable finger juncture, quite close to the articular membrane of the movable finger. There are three exceptions to this important pattern in the clade Euscorpiidae + Chactidae : (1) in Euscorpiidae (subfamily Scorpiopinae ), the eb–et series is arranged essentially in a straight line, or, the est–esb–eb juncture angles towards the fixed finger edge (see Soleglad & Sissom, 2001: figs. 112– 118); (2) in Euscorpiidae (subfamily Megacorminae , tribe Chactopsini ), the eb–et series is straight and closely arranged on the extreme distal aspect of the fixed finger (see Vachon, 1974: fig. 190); and (3) in Chactidae (subfamily Brotheinae , tribe Brotheini , subtribe Brotheina ) the eb–et series is arranged essentially in a straight line, or, the est–esb–eb juncture angles towards the fixed finger edge (see Soleglad & Fet, 2003: figs. 89–90, 118– 123). What is quite interesting about these three separate exceptions to the et–eb alignment seen in Euscorpiidae + Chactidae (all considered as separate derivations, by the way) is the tendency for other chelal trichobothria to exhibit a distal repositioning on the segment as well. For example, in the scorpiopines, tribe Scorpiopini , we see an unusual distal placement of trichobothrium Eb 3, which is of diagnostic importance to the genera of this tribe (Soleglad & Sissom, 2001: figs. 113–118). In genus Chactopsis (Megacorminae, Chactopini) several chelal trichobothria exhibit drastic distal dislocation, Et 3 –Et 5, Eb 2 –Eb 3, Db–Dt, and it (Vachon, 1974: figs. 190,192); and in the brotheines, tribe Brotheini , we see in subtribe Brotheina (all established as synapomorphies by Soleglad & Fet, 2003) that the eb–et series, which is situated distally, is either in a straight line or the est– esb–eb juncture angles towards the finger inner edge, the Et 2 –Et 5 series is situated more distally on the palm, in many cases, Et 5, Et 4, and sometimes Et 3, are found on the fixed finger, and series Db–Dt is situated more distally on the palm. Soleglad & Fet (2003: 137) considered these three exceptions to the eb–et arrangement as separate derivations from the arrangement illustrated in Fig. 1 (their character-21). From this analysis, it is clear that subtribe Brotheina is the most recently derived lineage in subfamily Brotheinae .

Figures

Figure 1: Pedipalp chelal trichobothrial patterns for series eb–et for chactoid families Euscorpiidae and Chactidae (in part). These figures illustrate the est–esb–eb juncture angling away from the fixed finger edge (i.e., eb is closest to the fixed finger edge), a demonstrated synapomorphy for Euscorpiidae + Chactidae (Soleglad & Fet, 2003). Specified species name lists are associated, from top to bottom, with patterns, left to right. Figures are from several sources, in part, (Vachon, 1974: fig. 229; Soleglad, 1976: figs. 72, 91; Soleglad & Fet, 2003: figs. 81–88; González-Sponga, 1996: fig. 153).