Scolopocryptops simojovelensis Edgecombe & Vahtera & Stock & Kallonen & Xiao & Rack & Giribet 2012, SP. NOV.

SCOLOPOCRYPTOPS SIMOJOVELENSIS SP. NOV. (FIGS 1–3)

Diagnosis: Scolopocryptops lacking margination on cephalic plate; paramedian sutures terminating on tergite 21; anterior margin of forcipular coxosternite lacking lateral tooth or bulge, median part of margin projecting anterior to lateral part; coxopleural process long, terminating in a robust pointed spine; two tibial spurs on legs 1–19, ventral spur only on leg 20; accessory spurs on legs 1–22 c. 20% length of the pretarsus.

Holotype: AMNH Ch-SH7, American Museum of Natural History amber arthropod collection, from Simojovel de Allende, Chiapas, Mexico.

Etymology: For Simojovel de Allende, the most prolific source of Chiapas amber.

Description: Length of body (anterior margin of cephalic plate to posterior margin of tergite 23) 29 mm. Cephalic plate lacking margination either laterally or posteriorly, its posterior margin overlying tergite 1 (Figs 1C, 3A). Seventeen articles in right antenna (left antenna preserves only a few basal articles, the remainder eroded from the inclusion); moderately long setae numerous over length of articles to at least article 8; articles 2 and 3 bearing a similar, moderate number of setae dorsally (neither is sparsely setose); short, dense setae on article 4 and more distal parts of antenna.

Anterior margin of forcipular coxosternite partly covered (Fig. 3C), only visible on lateral half of right side; exposed part of margin approximately straight, its more medial part anterior to its lateral part, lacking lateral tooth or lateral bulge.

Complete pair of paramedian sutures on tergites (TT)16-21 (Fig. 2A, B), anterior to this to at least T8 (and apparently as far as T5) a pair of lines of surficial crust run parallel to the course of the paramedian sutures on TT16-21 and evidently represent deposits along the sutures; paramedian sutures absent on TT1-3 and 22. Posterior part of tergites bearing several subtransverse anastomosing ridges (Fig. 2B), more prominent on posterior trunk segments to c. segment 21.

Paired tibial spurs on legs 1–19, smaller anterodorsal spur and larger ventral spur; ventral spur only on leg 20 (Fig. 1B), lacking on legs 21–23. Single tarsal spur on legs 1–21 (Fig. 1B, C); tarsal spurs lacking on legs 22 and 23. Pretarsus of legs 1–22 with moderately developed pair of accessory spurs (Fig. 1D); ultimate leg with small accessory spurs. Sternite of segment 23 with evenly concave posterior margin. Coxopleural pore field extending close to base of coxopleural process ventrad, posterior margin of pore field sinuous but without a re-entrant field devoid of pores dorsad (Fig. 3D). Dorsomedial spinose process of ultimate leg prefemur more than half the length of strong ventral spinose process (Fig. 2C, D). Setal density on distal articles of ultimate leg (Fig. 2D) apparently similarly sparse to that on proximal part (no evidence for clustered ‘bottle brush’ setae on any article).

Discussion: Although the new species is known from a single specimen, it exhibits distinct states for characters that, in combination, are routinely used in species diagnosis in Scolopocryptops. It is readily distinguished from all North American and Asian species of the genus by the absence of margination on the cephalic plate, a character that is invariant in species. Some of the states cited in the species diagnosis exhibit variability in geographically widespread extant species, but the condition in the fossil allows distinction from other species. For example, the paramedian sutures terminate on any of tergites 20–22 in S. mexicanus, but the state in the fossil (terminating on tergite 21) differs from that seen in S. macrodon or Scolopocryptops miersii (terminating on tergite 22). Likewise, the posterior-most leg with two tibial spurs may be either 18 or 19 in S. mexicanus and S. miersii, but the fossil (with two spurs on leg 19) is distinguished from S. macrodon (two spurs on leg 20). The shape of the coxopleural process and the development of the pretarsal accessory spurs are stable within species, and, in combination, the states are diagnostic.

The fossil can be reliably distinguished from each of the five extant Neotropical species of Scolopocryptops. Perhaps the most pertinent comparisons are with the two most geographically widespread species, S. mexicanus Humbert & Saussure, 1869, and S. melanostoma Newport, 1845, because their modern distributions include the area inhabited by S. simojovelensis in the Miocene. Both of these species occur in southern Mexico and range throughout Central America and the Caribbean, throughout which they are the only extant members of Scolopocryptopinae (Chagas Juniór, 2008). Compared to S. melanostoma the fossil has more strongly developed pretarsal accessory spurs (Fig. 1D), has the medial part of the forcipular coxosternal margin anterior to the lateral part (versus the opposite in S. melanostoma), possesses both dorsal and ventral tibial spurs on leg 19 (versus a ventral spur only on leg 19 in S. melanostoma), and has a ventral tibial spur on leg 20 (Fig. 1B). Following Chagas Juniór (2008), we apply the name S. mexicanus to Neotropical material that has generally been identified as Scolopocryptops ferrugineus (Linné, 1767). Compared to S. mexicanus, the Chiapas specimen lacks a lateral tooth on the forcipular coxosternal margin, and has a substantially longer coxopleural process (both a longer spinose distal part as well as a more sloping posterior margin when seen in lateral view; Fig. 2C; Attems, 1930: fig. 347 for S. ferrugineus). It appears to differ from both of these species in that antennal articles 2 and 3 bear numerous setae dorsally. Compared to the Brazilian Scolopocryptops piauhyensis Chagas, 2004, the new species has a less concave posterior margin of the ultimate sternite, and that sternite does not conceal as much of the coxopleural pore field. Scolopocryptops guacharensis Manfredi, 1957, from Venezuela (revised by Chagas Juniór, 2003b) has a much smaller dorsomedial spinose process on the ultimate leg prefemur, possesses an external tooth on the forcipular coxosternal margin, has paramedian sutures terminating on tergite 20 (versus 21 in S. simojovelensis), and has a strongly setose tibia and tarsus on leg pair 23.