Harmonicon rufescens F. O. Pickard-Cambridge, 1896

Figs 1 A – G, 4

Harmonicon rufescens F. O. Pickard-Cambridge, 1896: 756, pl. 33, fig. 3, 6, pl. 35, fig. 2–3 (juvenile).

Diplura rufescens: Raven, 1985: 153 (synonymy and transfer to Diplura).

Harmonicon rufescens: Maréchal & Marty, 1998: 500 (rejected synonym with Diplura).

Material examined.

Holotype: Brazil • ♂ imm., lower Amazon, Santarém, Pará; no date; F. O. Pickard-Cambridge and Austen leg; NHMUK (no registration number). Not examined.

Other material.

Brazil • ♀; Pará, Altamira [3°12'08.3"S, 52°13'36.4"W]; 14 April 2009; A. P. L. Giupponi and D. R. Pedroso leg.; UFRJ 2575 ) • 2 ♀♀, 5 j; same data as for previous; MNRJ 4371 • ♀, 4 j; same locality as preceding; 2–7 April 2011; D. R. Pedroso leg; MNRJ 4362 .

Diagnosis.

Females of H. rufescens and H. oiapoqueae present spermathecae with median branch ending in a blunt rounded tip and without additional lobules (Fig. 1 D – F; Drolshagen and Bäckstam 2011, fig. 5). Females of H. rufescens can be separated from H. oiapoqueae by the tarsal claw of the pedipalp with a double row of teeth (vs. unique row; Drolshagen and Bäckstam 2011, p. 92); and spermathecae lateral branch with its tip folded over the stem and without lobules (vs. tip bearing several lobules) (Fig. 1 D – F; Drolshagen and Bäckstam 2011, fig. 5).

Taxonomic notes.

Harmonicon was established by F. O. Pickard-Cambridge (1896) to accommodate a single species, H. rufescens, based on a presumed female specimen from Santarém, Brazil. Drolshagen and Bäckstam (2011, p. 91) were able to examine the holotype and noticed that “ Cambridge (1896) was incorrect in stating that the holotype of Harmonicon rufescens is a female; it is in fact a juvenile male ”. The female described here is from Altamira, also in the Pará state, Brazil, and located ca. 300 km from Santarém. Both localities are placed in the lower Amazons, have similar climate, low altitude, and are covered by dense or open Ombrophile Amazonian Forest and Savannas (Magnusson et al. 2008). Other Dipluridae species collected in Santarém at the same expedition to lower Amazon as H. rufescens also have large distribution range. Diplura sanguinea (F. O. Pickard-Cambridge, 1896) is widespread through North and Northeast regions of Brazil (Brescovit et al. 2021) and is also found in Colombia (Sherwood et al. 2023). Diplura nigra (F. O. Pickard-Cambridge, 1896) has been recorded from several localities around Santarém (Brescovit et al. 2021), and we examined specimens from other localities from Pará, Amazonas, Roraima, Rondônia, and Mato Grosso states in Brazil. The only other species described for the same Brazilian state is H. cerberus, from Pequiá cave, near Carajás, in the municipality of Parauapebas, but its male holotype has several troglomorphic characteristics, and its type locality is placed ca. 660 km away from Santarém (Pedroso and Baptista 2014). Besides, the region around the cave where H. cerberus was collected is covered by the Amazon “ canga ” vegetation, which covers areas rich in iron ores and has unique vegetation (Mota et al. 2018).

Description.

Female (UFRJ 2575). Carapace oblong, wider at middle portion, light orange-brown, covered with dark setae, caput slightly elevated, darker; cephalic area not shortened, darker furrows, margins of thoracic area with a row of long, thick, rigid, erect, and curved dark setae pointing ectally (Fig. 1 A). Clypeus long, with frontal margin carrying 19 median-to-long, thick setae facing forward (Fig. 1 A). Eye tubercle with 15 thick setae on its anterior margin; area between eyes with 11 short and thickened setae, and others abundant and dark but not thickened setae (Fig. 1 A). Eye formula: ALE> PLE> AME> PME. Ocular area much wider than long. Anterior eye row slightly recurved. Posterior eye row slightly recurved. Median ocular quadrangle wider than long, wider at its posterior margin. AME rounded, ALE and PLE elliptical, and PME reduced in size, oval. AME - AME separated by less than its diameter. AME contiguous to PME. AME separated from PME by around half of its diameter. ALE and PME contiguous to PLE. Fovea transverse and slightly recurved (Fig. 1 A). Labium wider than long with no cuspules (Fig. 1 B). Sternum longer than wide, covered by black stiff setae and brownish thin recumbent setae, one pair of labial comma-shaped sigilla clearly separated from each other, three sternal sigilla near margin on each side, increasing in size from first to last, the third one much larger and elliptical (Fig. 1 B). Chelicerae dark red with 10 promarginal teeth at left chelicera and 12 promarginal teeth at right chelicera, fangs furrow with denticles. Plectrum with 6–8 separated thick setae on left side and right side, respectively. Maxillae elongated with 25 cuspules at the right side and 31 at the left one (Fig. 1 B). Lyra at ventral side of maxilla, asymmetrical, formed by 6–7 modified thick and long setae, increasing in size in a basal to distal direction, with a distinct gap between the base of each seta (Fig. 1 C). Left lyra with six setae (Fig. 1 C), right lyra with seven (two broken) setae. Left lyra thick, erect, regularly curved setae (Fig. 1 C, arrows) placed distally and interspersed among the field of long and thin setae covering the retrolateral face of maxilla, five at the left side and four at the right side. Leg formula IV> I> II> III; length of segments (femur + patella + tibia + metatarsus + tarsus = total length): I – 8.4 + 2.8 + 8.3 + 6.9 + 5.1 = 31.5, II – 7.4 + 2.6 + 7.5 + 6.9 + 4.8 = 29.2, III – 6.7 + 2.3 + 7.0 + 8.2 + 4.6 = 28.8, IV – 8.6 + 2.7 + 9.6 + 10.8 + 4.9 = 36.6. Tarsi with few cracks covering almost all dorsal and lateral faces, except by basis and tip of article; all tarsi and metatarsi with thin scopula, metatarsi with inconspicuous scopula; pedipalp tarsi with middle to apical scopulae; pedipalp claw with seven teeth; ITC without teeth; STC teeth: I: 9–5, II: 9–4, III – IV: 10–4. Macrosetae: Leg I: femur pld 0–0 – 2, d 1–1 – 1, rld 0–0 – 1, patella 0, tibia v 1–1 – 3 right, p 0–1 – 1, v 1–1 – 2 left, metatarsus v 2–1 – 2; Leg II: femur d 2–1 – 0, pld 0–0 – 1 left, pld 0–2 – 1 right, patella pld 0–0 – 1 left, tibia p 0–0 – 1 left, p 0–1 – 1 right, v 1–2 – 2 right, v 1–1 – 2 left, metatarsus v 1–2 – 2, p 0–1 – 0; Leg III: femur pld 0–0 – 2 left, d 2–0 – 0, rld 0–2 – 1 left, rld 2–2 – 1 right, patella 0, tibia p 0–1 – 1, rld 1–0 – 0, r 0–2 – 1 left, r 0–1 – 1 right, v 2–0 – 2 left, v 2–2 – 2 right, metatarsus d 0–0 – 2, r 0–2 – 0 left, rld 1–0 – 0 left, r 1–2 – 2 right, p 2–1 – 0, v 2–2 – 2 right, v 3–2 – 3 left; Leg IV: femur rld 2–2 – 1, d 1–1 – 0 right, d 2–1 – 0 left, patella r 0–1 – 0, tibia rld 1–0 – 0, p 1–0 – 1, r 1–1 – 1, v 2–2 – 2, metatarsus rld 2–1 – 1 left, rld 2–2 – 1 right, r 0–2 – 0 left, pld 2–1 – 1, v 2–1 – 3 left, v 3–1 – 3 right. Abdomen light brown with no stripes (Fig. 1 A), covered with dark setae, venter uniformly brown. PLS longer than half of abdomen, with articulate fusules on all articles, and last article finger-like and with light patches of ventral cracks (Fig. 1 A). Spermathecae separated by ca. 1.5 × its length, with two sclerotised thick stems (or branches), originating from a common basis poorly sclerotised and translucent, each branch with almost the same thickness and length; median branch slightly curved laterally and with large, rounded, and blunt tip without vesicles; lateral branch straight, with a wider rounded head, with its tip rounded and folded upon the stem (Fig. 1 D – F).

TL 26.9. Carapace 10.2 long, 9.1 wide, carapace length / width 1.12. AME 0.32 mm, AME - AME 0.24 mm. Abdomen 16.7 long, 8.5 wide. Spinnerets: PMS 2.6 long; PLS 16.2 long, basal article 4.7, middle 4.9, distal 6.6.

Variation.

Females (n = 6). TL 24.4–32.9. Chelicerae with 10 to 13 promarginal teeth, plectrum with five to eight setae, 25 to 40 maxillary cuspules, and lyra with five to seven bristles.

Distribution.

Only known from Altamira and Santarém cities, Pará State, Brazil (Fig. 4).