Brotheini Simon, 1879

Soleglad, Michael E. & Fet, Victor, 2003, High-level systematics and phylogeny of the extant scorpions (Scorpiones: Orthosterni), Euscorpius 2003 (11), pp. 1-175 : 97-98

Tribe Brotheini Simon, 1879 , new rank

Type Genus. Brotheas C. L. Koch, 1837 .

Composition. The tribe is established here, embracing four genera from tropical South America. It is divided into two subtribes (the category not used before in scorpion systematics): Brotheina and Neochactina , established here.

Distribution. South America.

Taxonomic history. Sissom (2000a: 313) outlined an important taxonomic problem connected with the South American genera now included in the tribe Brotheini . The genus Hadrurochactas has often been considered a synonym of Broteochactas . Lourenço (1986, 1988) placed Hadrurochactas , along with Auyantepuia , Taurepania and Vachoniochactas as “species groups” in Broteochactas ; later, however, he resurrected Vachoniochactas as a valid genus (Lourenço, 1994a). González-Sponga (1996a) continued to recognize Hadrurochactas and Taurepania , and these two genera therefore were listed as valid genera by Sissom (2000a), while Auyantepuia was listed as a synonym of Broteochactas . Sissom (2000a) listed only two species of Hadrurochactas ( H. odoardoi and H. schaumii ). Monod & Lourenço (2001: 195–196) discussed these issues, and again considered Hadrurochactas a speciesgroup of Broteochactas ( “schaumii ” group), commenting that this decision “is, however, only preliminary”. In addition to Broteochactas odoardoi González-Sponga, 1985 and Broteochactas schaumii (Karsch, 1880) , Monod & Lourenço (2001) also listed in the “schaumii ” group the species Broteochactas brejo , Broteochactas mapuera , and a new species, Broteochactas polisi Monod & Lourenço, 2001 .

Diagnosis. Synapomorphies. Neobothriotaxy Ch2 present on ventral surface of patella; neobothriotaxy Ch2 present on external surface of patella; pectinal middle lamellae composed of one or two plates, semi-fused with anterior lamellae, fulcra if present, quite reduced. Important Symplesiomorphies. Patellar trichobothria distance between esb 1 and esb 2 is much greater than distance between em 1 and em 2; ventral surface of leg tarsus dominated with setal pair configuration, median row of spinules essentially obsolete.

Discussion. This tribe is well-defined within the chactids by its distinct neobothriotaxy Ch2 found on both the ventral and external surfaces of the patella. As with subfamily Chactinae , this neobothriotaxy is essentially fixed as to its number of accessory trichobothria and overall pattern distribution. Within this tribe, we can distinguish two subtribes based entirely on relative positions and configurations of key trichobothrial series of the chela. Although these diagnostic characters were briefly described in the Character Analysis section, we discuss them here in detail, quantifying the variability seen across the species of these two subtribes.

The primary character distinguishing two subtribes within Brotheini is the orientation of the eb and esb trichobothria. In subtribe Neochactina , the est–esb–eb juncture angles away from the fixed finger edge ( Figs. 124–125); trichobothrium eb is located at the base of the fixed finger, and positioned very close to the articular membrane at the fixed/movable finger juncture; and trichobothrium esb is located closer to the dorsal edge of the fixed finger, removed from the finger edge. In general, the eb–et series is positioned on the basal two-thirds of the fixed finger. In subtribe Brotheina , the est– esb–eb juncture, if not straight, angles toward the fixed finger edge ( Figs. 118–123); trichobothrium eb is removed from the finger edge, located more towards the dorsal edge of the fixed finger, never close to the articular membrane; and trichobothrium esb is located closer to the finger edge. In general, the et–eb series is located on the distal two-thirds of the fixed finger, but this is variable depending on the morphometric proportions of the chelal fingers. Vachon (1974: Figs. 224–225) first identified these differences for species Brotheas gervaisi (his Fig. 224) and Neochactas delicatus (identified by Vachon as Broteochactas delicatus , his Fig. 225). We follow Vachon’s designations of the eb and esb trichobothria (note that, in many of the trichobothria illustrated by González-Sponga (1996a), this author reverses the designations of eb and esb). It is important to note here that the eb–esb positional orientations exhibited in subtribe Neochactina are the same as that found in the brotheine tribe Belisariini , chactid subfamilies Chactinae and Uroctoninae , and in euscorpiid subfamilies Euscorpiinae and Megacorminae . Clearly this condition is relatively primitive within the clade “ Euscorpiidae + Chactidae ” and therefore, the eb–esb pattern exhibited in subtribe Brotheina is derived. In concert with the relative positions of the eb–et series distinguishing the two subtribes, the db–dt series also reflects these distinctions; i.e., db–dt series is situated on the basal two-thirds of the fixed finger in Neochactina and, in contrast, is located on the midfinger to distal two-thirds in Brotheina . The second character used to diagnose these subtribes is the relative positions of the Et 3 –Et 5 trichobothria. In subtribe Neochactina , these trichobothria are located on the distal aspect of the palm, below the articular membrane of the movable finger, between the fixed/movable finger juncture and the external condyle, and are never found on the fixed finger. In subtribe Brotheina , depending on the attenuation of the fingers, at least Et 5 is located adjacent to or dorsal of the fixed/movable finger juncture. In genus Brotheas and those species of Broteochactas that exhibit somewhat elongated fingers, Et 5, Et 4 and sometimes Et 3, are located dorsal of the fixed/movable finger juncture, Et 5 and Et 4 actually located on the fixed finger ( Figs. 118–121). The third character distinguishing these two subtribes is the location of the Db–Dt series. In subtribe Neochactina, Db is always located considerably proximal of the midpoint of the chelal palm and Dt is always located proximal of the movable finger external condyle and usually proximal of trichobothrium Est. In Brotheina , Db is located close to or distal of the palm midpoint and Dt is usually located distal of trichobothrium Est and many times, on species with longer fingers, is found on the fixed finger base. Figures 118–125 illustrate these three characters showing the complete spectrum of relative locations as seen in subtribe Brotheina . Except for the very short-fingered species, Broteochactas nitidus ( Fig. 122) and B. scorzai ( Fig. 123), we see consistency with all diagnostic characters described above. In these short-fingered species, only the primary character, the position of trichobothria eb and esb, is the most apparent. However, by closely comparing these two species with Neochactas sarisarinamensis ( Fig. 124) and N. laui ( Fig. 125), the subtle differences between the relative positions of Et 5 –Et 3 and Db–Dt series are evident.

It is interesting to point out here that, when González-Sponga (1978) created genus Auyantepuia to distinguish species Broteochactas scorzai from other species of Broteochactas , he used, in part, the primary diagnostic character presented here to distinguish the two Brotheini subtribes. In particular, González-Sponga attributed the pattern we define, in part, for subtribe Brotheina , to his new genus Auyantepuia . Francke & Boos (1986) discussed González-Sponga’s result and dismissed it because the character was not consistent within species of Broteochactas (i.e., they examined species which exhibited both the Neochactina and Brotheina eb–esb patterns described in this paper). Francke & Boos’s logic for rejecting Auyantepuia is not particularly sound here, since González-Sponga created the new genus to accommodate these distinctions. However, whether or not one accepts Francke & Boos’s reason for rejecting Auyantepuia , the point becomes mute. This is because Francke & Boos (1986) redescribed Broteochactas nitidus , based on a lectotype designated by them, thus confirming it as the type species of Broteochactas . Since this type species exhibits the same pattern as attributed to Auyantepuia by González-Sponga, and our subtribe Brotheina , Auyantepuia , in our opinion, remains a synonym of Broteochactas . This, in turn, requires that those species of Broteochactas González-Sponga contrasted with Auyantepuia must be placed in a different genus. We do this here by establishing the new genus Neochactas , which becomes the type genus for subtribe Neochactina . We discuss below in the appropriate subtribe sections the reallocation of species of the tribe Brotheini necessitated by this change.