Harmonicon F. O. Pickard-Cambridge 1896
Creators: name: Wermelinger-Moreira, Gabriel
name: de Souza Castanheira, Pedro
name: Baptista, Renner Luiz Cerqueira
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Dipluridae
Harmonicon

description: Harmonicon F. O. Pickard-Cambridge, 1896
Type species.
Harmonicon rufescens F. O. Pickard-Cambridge, 1896, by monotypy.
Composition.
Five species: Harmonicon audeae Maréchal & Marty, 1998; H. candango sp. nov.; H. cerberus Pedroso & Baptista, 2014; H. rufescens F. O. Pickard-Cambridge, 1896; and H. oiapoqueae Drolshagen & Bäckstam, 2011.
Diagnosis.
Harmonicon and the other three lyrate genera of Diplurinae (i. e., Diplura, Trechona and Harpathele) can be separated from Linothele, by the presence of lyra on the ventral side of each maxilla (Fig. 1 C; Pedroso et al. 2018, fig. 9; Pedroso et al. 2019, fig. 3 A – H; Wermelinger-Moreira et al. 2024, figs 1 C, 3 G). Harmonicon, Diplura and Harpathele differ from Trechona by having lyra with less than 35 macrosetae in a unique row (Fig. 1 C; Pedroso et al. 2018, fig. 9; Wermelinger-Moreira et al. 2024, figs 1 C, 3 G) (vs. more than 35 setae arranged in a plate with several rows; Pedroso et al. 2019, fig. 3 A – H), spinnerets usually longer than abdomen (Fig. 1 A; Wermelinger-Moreira et al. 2024, figs 5 A) (vs. reaching up to ½ abdomen length on females and ⅔ on males; Pedroso et al. 2019, fig. 4 A, B), fovea slightly transverse (Fig. 1 A; Wermelinger-Moreira et al. 2024, fig. 1 A) (vs. fovea strongly recurved; Pedroso et al. 2019, fig. 4 A – C) and medium-sized to large adult body size (females at most 25 mm, males 20 mm) (Figs 1 A, 2 A; Wermelinger-Moreira et al. 2024, figs 1 B, 3 B) (vs. large adults, females at least 35 mm, males 23 mm; Pedroso et al. 2019, fig. 4 A – C). Harmonicon and Harpathele differ from Diplura by the maxilla of pedipalp with a dorsal transverse suture bearing a strong curve at its basal third (Fig. 1 C; Wermelinger-Moreira et al. 2024, fig. 1 C) (vs. straight or slightly curved at its basal third; Pedroso et al. 2018, fig. 9); a field of numerous long and thin setae between the lyra and the transverse suture (Fig. 1 C; Wermelinger-Moreira et al. 2024, fig. 1 C) (vs. no or just few interspersed short thin setae; Pedroso et al. 2018, fig. 9); and a field of small rigid bristles (spiniform setae) below the same suture (Fig. 1 C; Wermelinger-Moreira et al. 2024, fig. 1 C) (vs. no rigid bristles; Pedroso et al. 2018, fig. 9). Furthermore, Harmonicon and Harpathele males do not bear a field of rigid macrosetae on the prolateral face of metatarsus I and have the tibia of pedipalp long and thin (Fig. 2 B; Pedroso et al. 2018, fig. 22) (vs. with such field or clasper and tibia of pedipalp clearly inflated and relatively short; Pedroso et al. 2018, figs 14, 21).
Harmonicon can be distinguished from Harpathele by carapace brownish red, strongly contrasting with uniform dark grey abdomen in living specimens (Figs 1 G, 3 G) (vs. carapace brownish not strongly contrasting with abdomen colour; Wermelinger-Moreira et al. 2024, figs 1 A, 3 A), dorsum of abdomen without transverse stripes (Figs 1 A, 2 A, 3 A) (vs. with transverse light stripes, sometimes difficult to see in males; Wermelinger-Moreira et al. 2024, figs 1 B, 3 B, 4 A, 5 A), and lyra formed by 5–8 macrosetae relatively thick and short, each one with basis clearly separated by a gap from the other setae, and apex usually strongly curved (Fig. 1 C; Maréchal and Marty 1998, fig. 2 A – B; Drolshagen and Bäckstam 2011, fig. 6; Pedroso and Baptista 2014, fig. 6) (except Harmonicon candango sp. nov., figs 2 H, 3 C) (vs. 25–31 macrosetae, usually long, with bases closely placed and apex almost straight or weakly curved, but with some clavate tips in females; Wermelinger-Moreira et al. 2024, figs 1 C, 3 G, 4 B, 5 G, 6 A – D). Furthermore, Harmonicon females have spermathecae formed by two branches rising from one base (Figs 1 D – F, 3 D – F; Drolshagen and Bäckstam 2011, fig. 5) (vs. one long, curved, and flattened branch, sometimes with a small round lateral vesicle or lobule; Wermelinger-Moreira et al. 2024, figs 2 A – D, 4 D), and males have embolus reaching between 1.1 and 1.5 as long as the palpal bulb in retrolateral view (Fig. 2 B, D; Maréchal and Marty 1998, fig. 4; Drolshagen and Bäckstam 2011, fig. 1; Pedroso and Baptista 2014, fig. 7) (vs. 2 or more times longer than bulb; Wermelinger-Moreira et al. 2024, figs 3 C, F, 5 E).
Taxonomic notes.
A comparative diagnosis of Harmonicon and other genera of Dipluridae was published by Pedroso et al. (2018). Since then, Harpathele was added to the subfamily, and some updates were made to the diagnosis presented above.
All described Harmonicon species have colour pattern and somatic traits generally similar and less variable, with the exception of H. cerberus, which exhibits some troglomorphic characters, such as the fused and reduced lateral eyes and the pale yellow carapace (Pedroso and Baptista 2014, fig. 1–3). Most diagnostic characters are related to the genitalia or to sexual dimorphic traits.
An interesting diagnostic somatic character is the shape of the sternal sigilla III. Harmonicon rufescens, H. oiapoqueae, and H. candango sp. nov. share sternal sigilla III with similar longer than wide ellipsoid shape (Figs 1 B, 2 G, 3 B; Drolshagen and Bäckstam 2011, fig. 3). Those sigilla strongly contrast with the rounded (slightly longer than wide) sigilla of H. audeae (Maréchal and Marty 1998, fig. 1 C). As noted by Pedroso et al. (2018), some species of Harmonicon do not bear a lyra with hook-shaped macrosetae. Instead, they are clavate with a long and weaker bent beginning at the median third of the seta, as in H. candango sp. nov. (Fig. 2 H, 3 C). Additional thickened and more sclerotised setae on the maxillae may represent a diagnostic character for at least some species of Harmonicon. They are represented by three to five stiff setae placed at the distal half of the maxilla, away from the most basally placed lyra, and at the beginning of the large field of elongated and thin setae that cover its prolateral face, as in H. cerberus (Pedroso and Baptista 2014, fig. 6), H. rufescens (Fig. 1 C), and also in H. oiapoqueae (Pedroso et al. 2018). In females, the tarsal claw of the pedipalp has double row of teeth in H. rufescens, H. audeae, and H. candango sp. nov., but only one row of teeth in H. oiapoqueae (see Drolshagen and Bäckstam 2011, p. 92).
The most useful sexual characters in males are those from the palpal bulb and modified tibia and metatarsus of leg I. Their tibia I bears one distal prolateral macroseta besides the retrolateral spur. In H. audeae, the prolateral macroseta is thin and elongated (Maréchal and Marty 1998, fig. 3 C, D). In H. candango sp. nov., that macroseta is lost, but the dark insertion plate is clearly visible (Fig. 2 J), and in H. oiapoqueae, a similar plate seems to be present in an Internet photograph taken by Droslhagen, but it is not mentioned or illustrated in the description (Drolshagen and Bäckstam 2011, fig. 7). The only species apparently without such macroseta is H. cerberus (Pedroso and Baptista 2014, fig. 11), but its holotype has been destroyed during the MNRJ ’ s fire. The distal retrolateral spur of tibia I is similar in all described species, projected like a small, weakly curved rod in retrolateral view and slightly projected laterally in ventral view. The distal megaspine over the spur is a little more variable in both thickness and curvature. It is more elongate and curved and has a basis slightly thicker in H. oiapoqueae (see Drolshagen and Bäckstam 2011, fig. 7) and H. audeae (see Maréchal and Marty 1998, fig. 3 C, D) than in H. cerberus (see Pedroso and Baptista 2014, fig. 11) and H. candango sp. nov. (Fig. 2 I, J).
In relation to metatarsus I, most species have a retrolateral tubercle at its basal third, but it is absent in H. audeae (see Maréchal and Marty 1998, fig. 3 D). The shape and size of the tubercle are similar in the three species where it has been recorded, where it appears as a small mound with a rounded point (Fig. 2 J; Drolshagen and Bäckstam 2011, fig. 7; Pedroso and Baptista 2014, fig. 11). In H. candango sp. nov. and H. cerberus, there is a retrolateral macroseta at the ventral side near the retrolateral tubercle of metatarsus I (Fig. 2 J; Pedroso and Baptista 2014, fig. 11), which is not found in H. oiapoqueae (see Drolshagen and Bäckstam 2011, fig. 7). In H. candango sp. nov., that macrosetae is placed at the same level of the tubercle (Fig. 2 J), but it is placed basally to the tubercle in H. cerberus (Pedroso and Baptista 2014, fig. 11).
The palpal bulb differs among the species. In H. audeae, it is thin and piriform (Maréchal and Marty 1998, fig. 4 A – C), while it is wider and more rounded in H. cerberus, H. oiapoqueae, and H. candango sp. nov. (Fig. 2 C – F; Pedroso and Baptista 2014, fig. 7–9; Drolshagen and Bäckstam 2011, fig. 1, 2). In retrolateral view, the embolus may be about as long as (H. cerberus, see Pedroso and Baptista 2014, fig. 7) or a little longer (H. oiapoqueae, ca. 1.2 ×, Drolshagen and Bäckstam 2011, fig. 2) than the bulb proper, but may also be elongated (H. candango sp. nov., ca. 1, 5 × longer, Fig. 2 B, D).
In females, the spermathecae and its accessory parts are very useful for diagnosis. The median branch of the spermathecae varies from about the same length as the lateral branch and ending in a rounded, blunt tip (H. oiapoqueae, Drolshagen and Bäckstam 2011, fig. 5) to a little longer than the lateral branch and ending in a tip with 3–4 lobules (ex. H. candango sp. nov., Fig. 3 D – F). The lateral branch may have its tip folded over its stem (ex. H. rufescens, Fig. 1 D – F) or with several lobules. The lobulated tip may have up to 4–5 lobules (H. oiapoqueae, Drolshagen and Bäckstam 2011, fig. 5) or be very wide and multilobulate (Fig. 3 D – F).
Distribution.
The genus can be found in several localities in the Amazon region, in French Guiana and Pará State, North Brazil. Its geographical range is here extended to Brasília, Distrito Federal, Central-West region of Brazil, in the Cerrado biome. There are also records of undescribed species from Amazonian Peru, the Northeast region, and additional states from the Central-West region of Brazil, according to Pedroso et al. (2018).
description: Published as part of Wermelinger-Moreira, Gabriel, de Souza Castanheira, Pedro & Baptista, Renner Luiz Cerqueira, 2024, A new species of Harmonicon F. O. Pickard-Cambridge, 1896, from central-west Brazil and redescription of H. rufescens F. O. Pickard-Cambridge, 1896 (Araneae, Mygalomorphae, Dipluridae), pp. 261-271 in Evolutionary Systematics 8 (2) on pages 261-271, DOI: 10.3897/evolsyst.8.141847