Phrynus luisdearmasi, Dunlop & Bartel, 2025

Phrynus luisdearmasi sp. nov.

Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3

Etymology. The new species-group name is proposed in honour of Prof. Luis F. de Armas for his extensive contributions towards the study of whip spiders, and other arachnids, in the Neotropics.

Type series. MB.A. 1747 . Holotype and only known specimen. From Dominican Republic amber. Miocene: Burdigalian (ca. 20.43 – 15.97 Mya).

Diagnosis. Fossil Phrynus species from the ‘A’ group sensu Quintero (1983), body length of holotype ca. 8 mm, with leg I tibia subdivided into 34 articles. Ventral pedipalp femoral spination pattern, FvI–II> FvV> FvIII> FvVI> 5vIV; dorsal pedipalp patella spination pattern Pd5> Pd3> Pd2> Pd4> Pd6> Pd1 = Pd7, with Pd6 almost the same size as Pd4; both dorsal pedipalp tibial spine 1 and proximal ventral tibial spine pronounced. Closely-related living (and fossil) species have less than 34 leg I tibial articles. Relatively large dorsal tibial spine 1 in the new species also differentiates it from both the amber species Ph. resinae and the extant species Ph. marginemaculatus , Ph. alejandroi Armas & Teruel, 2010 , Ph. eucharis Armas & Pérez González, 2001 , and Ph. kennidae Armas & Pérez González, 2001 , in which this tibial spine is noticeably smaller. Pedipalp spination of the new species resembles that of Ph. hispaniolae Armas & Pérez González, 2001 , and Ph. decoratus Teruel & Armas, 2005 , both of which also have a more pronounced dorsal tibial spine 1, but in the new species Pd6 and Pd4 are similar in size whereas in Ph. decoratus P6 is noticeably shorter than P4; while the number of tibial articles (34) differentiates the new fossil from Ph. hispaniolae which has, at most, only 32 articles.

Description. Almost complete inclusion, visible in both dorsal and ventral views ( Fig. 1 View FIGURE 1 ); limb series almost complete, better preserved on right side. Total preserved length ca. 8. Carapace reniform, wider than long; length 2.9, maximum width 4.2. Median and lateral eyes present ( Fig. 2 View FIGURE 2 ), but lateral eyes inconspicuous. Chelicerae largely tucked beneath carapace, total length ca. 1.5; pattern of cheliceral dentition equivocal. Sternal elements between leg coxae also equivocal.

Pedipalps robust and spinous ( Fig. 2 View FIGURE 2 ). Article lengths: trochanter 0.8, femur 1.4, patella 2.4, tibia 1.4, tarsus 1.2. Trochanter with 4 spines, from proximal to distal second spine largest; trochanter with at least three long setae. Femur with six dorsal spines ( Fig. 3B View FIGURE 3 ), numbered from proximal to distal; Fd1–3 larger than 4–6, but angle of preservation makes resolving whether there was a common F1+F2 base sensu Armas & Pérez González (2001) equivocal, and also makes it difficult to accurately determine the relative heights of 4–6. Femur also ventrally with six spines (designated by Roman numerals sensu Seiter et al. 2022), FvI–II longest, followed by FvV, then FvIII and FvVI, with 5vIV shortest. Patella wide with eight (left, Fig. 3B View FIGURE 3 ) and seven (right) dorsal spines, again numbered from proximal to distal. From longest to shortest: Pd5> Pd3> Pd2> Pd4> Pd6> Pd1 = Pd7. Additional (eighth) spine on left side shorter than Pd7 ( Fig. 3B View FIGURE 3 ); not usually included in notation scheme. Ventrally with at least 5 subequal spines, but details lacking. Tibia with three dorsal spines ( Fig. 3B View FIGURE 3 ); from proximal to distal 1 and 3 approximately equal in length, spine 2 about twice as long as 1 and 3. Tibia with at least two ventral spines ( Fig. 2D View FIGURE 2 ), proximal one shorter than distal one. Details equivocal, but presence of a well-developed first ventral tibial spine here distinctive. Tarsus sickle-shaped, bearing a tuft of seta (the cleaning organ) about midway along its length ( Figs 2B, D View FIGURE 2 ); no additional spine on the prodorsal surface.

Legs gracile ( Fig. 1 View FIGURE 1 ), leg I especially elongate and slender. Leg I article lengths: femur 6.9, patella 0.5, tibia 13.3, tarsus at least 8.5, but distal tip equivocal. Both tibia and metatarsus with multiple short articles, 34 the tibia ( Fig. 3A View FIGURE 3 ) and at least 50 tarsal elements. Leg II article lengths: femur 5.1, patella, 0.5, basitibia 4.2, distitibia 2.5, basitarsus 0.6, tarsus 0.7. Leg III article lengths: femur 6.0, patella 0.5, basitibia 3.7, remaining articles ca. 4.4, but details equivocal. Leg IV article lengths: femur 5.5, patella 0.5, basitibia 4.4, distitibia 2.9, basitarsus 0.7, tarsus 0.8. Basitibiae of legs II–IV with weakly expressed subdivision into three articles, distal basitibiae and distitibiae with several long trichobothria, but details equivocal. Tarsi of at least legs II and IV subdivided into three tarsomeres; tarsus terminates in a pair of small claws. This tarsal configuration was probably present in leg III too, but structure of leg tip here equivocal.

Opisthosoma broadly oval ( Fig. 1 View FIGURE 1 ), anteriormost part slightly tucked under posterior carapace margin, opisthosoma also tapering somewhat posteriorly; length 5.4, maximum width 3.9. At least 8 tergites visible, anteriormost elements slightly recurved, otherwise all with straight posterior margins; at least 5 tergites with pairs of indented muscle apodemes towards centre of the plate. Ventrally ( Fig. 1C–D View FIGURE 1 ), genital operculum, and succeeding sternite, with notably recurved posterior margins. Genital structures associated with genital plate equivocal. Other sternites poorly preserved, but ca. five elements demarcated by weak transverse lines. Posteriormost opisthosomal segments converge towards a blunt pygidium, but details of individual elements here difficult to resolve.