Holmelgonia, JOCQUE & SCHARFF, 2007

Lin, Shou-Wang, Lopardo, Lara & Uhl, Gabriele, 2022, Evolution of nuptial-gift-related male prosomal structures: taxonomic revision and cladistic analysis of the genus Oedothorax (Araneae: Linyphiidae: Erigoninae), Zoological Journal of the Linnean Society 195, pp. 417-584 : 482

HOLMELGONIA JOCQUÉ & SCHARFF, 2007

Type species: Elgonia nemoralis Holm, 1962 .

Diagnosis, description and taxonomic remarks: The resemblance of Holmelgonia to Callitrichia and other related genera (i.e. Oedothorax , Toschia and Ophrynia ) has not been mentioned in previous publications. Regarding the shape of embolic division, the enlarged terminal part of paracymbium, the vastly erected palpal tibia prolateral apophysis and the general epigyne morphology, Holmelgonia is similar to numerous Callitrichia species. Nzigidahera & Jocqué (2014) described Holmelgonia as characterized by the absence of cheliceral stridulation ridges, the presence of a double ventral row of setae on the femora, the long tibial spines (two to three times as long as the diameter of the segment), tibial chaetotaxy 2-2-1-1, TmI between 0.32 and 0.7, the absence of prosomal modification and the apophysis on the dorsal side of the palpal tibia. However, all these features are not unique to the members of this genus. One potential diagnostic feature, the absence of cheliceral stridulatory ridges, is actually present in our studied species ( Ho. basalis , Fig. 22B ), and the chelicera of Ho. disconveniens Nzigidahera & Jocqué, 2014 (SEM photo, figs 2–3 in Nzigidahera & Jocqué 2014) shows a scaly lateral surface without setae, which could also be interpreted as stridulatory striae (fig. 3 shows the detail of the anterior surface, instead of the lateral surface). Despite the lack of defining features for this genus, and the sister-relationship of Ho. basalis and Callitrichia shown in the present study, this genus differs from Callitrichia in the lack of truncated protegulum and the presence of a central embolar apophysis ( Fig. 36B, D , arrow). The latter structure is present in all species with known males, except Ho. discoveniens and Ho. afromontana Nzigidahera & Jocqué, 2014 . Due to the lack of synapomorphies defining this genus, the monophyly of Holmelgonia remains untested ( Nzigidahera & Jocqué 2014). In our phylogenetic hypothesis ( Fig. 3 ), Ho. basalis resulted sister to Callitrichia (Clade 40), a relationship supported by the presence of a rim at the distal area of the protegulum (Ch 38, synapomorphic) and posterior lateral spinneret with more than three aciniform gland spigots (Ch 116, homoplastic). Since only one Holmelgonia species was represented in our analysis, it is yet premature to decide whether the genus is a monophyletic assemblage sister to Callitrichia , or a paraphyletic set of taxa that should in turn require taxonomic actions. Further phylogenetic analyses with a thorough species representation of Holmelgonia , including the type species Ho. nemoralis , as well as Callitrichia and other related taxa, is needed.

Distribution: Ivory Coast, Cameroon, Congo, Burundi, Tanzania, Uganda, Kenya, Malawi and Mozambique.

Natural history: Species of this genus were found in lower vegetation, forest litter and by pitfall traps ( Jocqué 1981; Jocqué & Scharff 1986; Scharff 1990a). Most species live at high altitude and have small endemic ranges, while some have a wide distribution at midaltitude ( Nzigidahera & Jocqué 2014).

Figures

Figure 3. Continuation of Figure 2, showing Clade 36.

Figure 22. Male chelicerae, stridulatory striae on lateral side. A, ‘Oedothorax’ meghalaya. B, ‘Oe.’ uncus. C, Holmelgonia basalis. D, Callitrichia holmi. E, Ca. picta. F, Ca. gloriosa. G, Ca. convector. H, Ca. sellafrontis. I, Ca. juguma. J, Ca. uncata. K, Ca. pilosa. L, Ca. usitata. M, Ca. legrandi. N, Ca. macrophthalma. O, Ca. muscicola. P, Ca. latitibialis. Q, Ca. longiducta. R. Nasoona setifera. S, N. crucifera. Scale bars 0.05 mm.

Figure 36. Holmelgonia basalis Jocqué & Scharff, 1986. A–D, male right palp, images flipped horizontally. A, retrolateral view. B, prolateral view. C, dorsal view. D, ventral view. E, F, epigyne. E, ventral view. F, external morphology. G, male posterior median spinnerets and posterior lateral spinnerets. H, female right spinnerets. I, female right posterior lateral spinneret. Scale bars 0.1 mm.