Triaena mirabilis Tullberg, 1871

Body length: 0.51 mm (Holotype). Habitus cylindrical and robust, typical of Friesea. Color bluish-gray with ventral of head, legs and sternites white. Secondary granules moderately developed. Antennae shorter than cephalic diagonal. Ratio antenna: cephalic diagonal = 1: 1.4. Ant IV with apical bulb simple and subapically displaced on ventral side; subapical organite, dorsolateral S-microchaeta and 6 S-chaetae present dorsally (Fig. 1). Sensory organ of Ant III formed by five S-chaetae: two internal S-microchaetae bent externally and freely exposed; two subcylindrical guard S-chaetae and one smaller ventral S-microchaeta (Fig. 2). Ant I with 7 simple chaetae and Ant II with 11 chaetae, of which 10 are simple and one is strongly spatulate dorsoexternally (see detail in Fig. 7).

Head with 8+8 eyes in heavily pigmented eye-patch. Mandible strong with 5 unequal teeth; basal tooth measuring approximately twice the size of the others; maxilla head typical of the genus, with three lamellae; internal lamella with about 6 denticles (Fig. 3). Buccal cone short; Pre-labral/labral chaetae arranged according to the formula: 2/5,5,4. Labium typical of the genus, with papillated chaeta L, chaeta F about twice the length of E (Fig. 4).

Chaetotaxy of legs I, II, III. Subcoxae I 1,3,3; Subcoxae II 0,2,2; Coxae 3,6,7; Trochanters 5.4,4; Femora 11,10,10; Tibiotarsi 18,18,17, without M chaeta. Tibiotarsi I-III with 4,5,5 clavate tenent hairs, respectively (2 dorsal and 2 ventral on Tita I; 3 dorsal and 2 ventral on Tita II and III) (Figs 5, 6). Subcoxa I of legs I-III and lateral region of Abd V with hemispheric tegumentary protuberance constituted of primary granules (see detail of Fig. 7). Ungues toothless.

Dorsal body. Composed of short ordinary chaetae, slender S-chaetae, slightly longer than ordinary, and strongly clavate chaetae laterally on head and abdominal tergites IV-VI (Fig. 7). Head chaetotaxy composed of a0, d0, d2-5, sd1-5, oc1-3, c1-2, p1-2. Th I with 2+2 simple chaetae. Abd IV with 2+2 small clavate dorsolateral chaetae; Abd V with 2+2 long clavate dorsal chaetae; Abd VI with 10 strongly clavate chaetae arranged in three linear rows, as 4,4,2 (Fig. 7 and detail). Formula of S-chaetae by half tergite: 022/11111.

Ventral tube with 3+3 chaetae. Abdominal sternites II-V with 4+4, 5+5, 12+12, 5+5 chaetae, respectively (Fig. 8). Tenaculum and furca absent; furcal area with 2+2 microchaetae. Anal valves with 11-12 chaetae and one hr chaeta. Male genital plate with 2+2 pregenital chaetae, 4+4 eugenital and 9 circungenital chaetae (Figs 8, 9).

Holotype male. BRAZIL, Amazonas State: Presidente Figueiredo municipality, forest leaf litter of Amazon Rainforest, coordinates 02°02'56"S, 60°06'08"W, 23.IV.2008, Hamada, Azevedo, Neiss, Silva & Meneses leg. (CM/MNRJ slide number 2538).

The specific name multiclavata is derived from Latin, meaning bearing nails, and is an allusion to the numerous clavate chaetae arranged along the tergites.

Friesea multiclavata sp. nov. can be included in the reducta-group, which is composed of 14 species, according to Queiroz and Mendonça (2015), based on the following characters: 8+8 eyes and absence of furca and anal spines (Table 1). Despite the absence of anal spines, most species in this group, with the exception of Friesea africana Delamare Deboutteville, 1953, have some degree of chaetae modification on Abd VI. In this sense, the new species is unique within this group since it also presents modified chaetae on head and antennae.

Friesea multiclavata sp. nov. is very similar to Fr. albithorax Massoud & Thibaud, 1980 (Antilles), Fr. lobulata Palacios-Vargas & Díaz, 1986 and Fr. mucumontana Palacios-Vargas & Díaz, 1986 (Venezuela) mainly for sharing the 2+2 chaetae on Th I, clavate chaetae on body and 18,18,17 chaetae on tibiotarsi I-III. However, Fr. multiclavata sp. nov. has a simple apical bulb, 4,5,5 tenent hairs on tibiotarsi and ungues without teeth while Fr. lobulata has a trilobed apical bulb, only two clavate tenent hairs on legs I-III and toothed unguis. Friesea multiclavata sp. nov. is uniformly bluish-gray colored, while Fr. albithorax presents white thoracic tergites and the rest of the body is grey. Moreover, Fr. multiclavata sp. nov. is unique among the four species here referred, by the 10 strongly clavate chaetae on Abd VI, while the others have six (Fr. lobulata and Fr. mucumontana) or eight (Fr. albithorax) clavate chaetae.

Friesea multiclavata sp. nov. has an inconspicuous tegumentary protuberance on subcoxa I of legs I-III and ventrolaterally on Abd V (Fig. 7), also found in Fr. reducta and Fr. boitata. This structure was first mentioned by Massoud and Thibaud (1980) in specimens of Fr. reducta from Lesser Antilles. Later on, Fr. boitata was also found to possess the same structures on subcoxae I and Abd V. According to Queiroz and Mendonça (2015), it is possible that these structures were not mentioned in other descriptions as they may have not been properly visualized.

Although there are no phylogenetic studies for Neotropical species of Friesea, the proposition of a group relying on morphological similarities, such as reducta-group, represents the first step towards a better understanding of the genus’ morphological diversity in the biogeographical region. As proposed by Queiroz and Mendonça (2015), it is possible to distinguish “subgroups” of species within this group based on the number of chaetae on Th I, being 2, 3 or 4 by half tergite. Despite that, we believe that the striking resemblance of these species, especially those previously mentioned with 2+2 chaetae on Th. I, suggests close relationship between them.

While further studies may clarify phylogenetic relationships, comparative morphological studies are still the mainframe for species recognition. In this sense, all described species in the mentioned subgroup can be distinguished mainly based on body chaetotaxy, especially chaetae morphology, such as clavate chaetae. This character is considered to be consistent and, therefore, it is widely used, especially for recently described species.

Figures 1–6. 

Friesea multiclavata sp. nov. holotype male: (1) Ant III-IV in dorsal view; (2) Ant III-IV in ventral view; (3) maxillae in dorsal view; (4) half labium in ventral view; (5) Tita II in ventrolateral view; (6) Tita II in dorsolateral view.

Micranurida africana Massoud, 1963

Body length 0.9 mm (Holotype). Habitus elongated and cylindrical, paratergites not developed. Secondary granules moderately developed. Color white, in ethanol. Antennae shorter than cephalic diagonal. Ratio antenna: cephalic diagonal = 1: 1.6. Ant IV with trilobed apical bulb, subapical organite apically displaced, next to apical bulb; 6 long S-chaetae (S1-S4, S8, S9?); dorsolateral S-microchaeta absent. Ant III and Ant IV dorsally fused. Antennal organ III with two inner small and curved S-microchaetae, two subcylindrical guard S-chaetae and one S-microchaeta ventrally; dorsal guard S-chaeta apically displaced, towards Ant IV and aligned to S2 and S3, and as long as S-chaetae of Ant IV (Figs 10, 11). Ant II with 11 chaetae and Ant I with 6 chaetae.

Head. Eyes absent, PAO circular with 8–9 vesicles, rosette-like (Fig. 12). Central head chaetotaxy with d1–5, sd3–5 (chaetae sd1,2 absent – probable homology), oc1–3, p1–3; c row of chaetae is absent. Maxilla styliform; Mandible with 7 teeth: 2 large basal, 3 subequal intermediate and 2 apical (Fig. 13). Pre-labral/labral chaetae arranged according to the formula: 4/2,3,5,2 (Fig. 14). Labium truncate with C and D chaeta apically displaced (Fig. 15).

Chaetotaxy of legs I, II, III. Subcoxa I 1,3,3; Subcoxa II 0,2,2; Coxa 3,6,8; Trochanter 6,6,6; Femur 12,12,11; Tibiotarsus 19,19,18; M chaetae basally displaced (Figs 16–18). Unguis of leg I with a strong basal tooth on inner edge (Fig. 16); unguis of legs II and III with small basal tooth on inner edge (Fig. 18).

Dorsal chaetotaxy of tergites consisting of simple, short and subequal chaetae and thin and long S-chaetae. Formula of S-chaetae by half tergite: 022/11111. Ratio ordinary chaeta: S-chaeta= 1: 4.5. Th I with 2+2 chaetae. Th II with dorsolateral S-microchaetae; Th II and III with one lateral ordinary chaeta posteriorly displaced. Abd VI with 8 chaetae, which 4 arranged in a row (Fig. 19).

Ventral tube with 3+3 chaetae. Abdominal sternites II-V with 2+2, 2+2, 5+5 and 3+3 chaetae, respectively (Fig. 20). Tenaculum with 3+3 teeth. Furca well developed: manubrium with 20 chaetae, dens with 5–6 chaetae; mucro with two lamellae and slightly curved apex (Fig. 21). Ratio mucro: dens = 1: 2.3. Each anal valve with 13 chaetae and 3 hr. Genital plate of male with 5+5 eugenital chaetae and 10 circungenital chaetae (Fig. 22).

Holotype male. BRAZIL, Amazonas State: Manacapuru municipality, forest leaf litter of Amazon Rainforest, coordinates 03°12'23"S, 60°40'21,0"W, 29.III.2008, Nessimian, Querino, Pepinelli, Azevedo & Neiss leg. (CM/MNRJ slide number 2523).

The name of this species is a reference to the legendary Amazonian giant snake called Boiuna, in Amerindian Tupi Language. According to the legend, a huge snake grows to unrealistic proportions and, as it crawls through dry land, it leaves behind the grooves that later on become the Igarapés.

The broadness and vagueness of the current diagnosis for Furculanurida was discussed in some studies involving species of this genus and its similarity to other genera (Thibaud and Palacios-Vargas 2000, Queiroz and Fernandes 2011, Zon et al. 2014). Recently, Zon et al. (2014) drew attention to the fact that Furculanurida has a poor definition, with many morphological features overlapping with the diagnosis of Pseudachorutes Tullberg, 1871 and Stachorutes Dallai, 1973 (see Table 2). The most conflicting aspects are related to number of eyes, PAO shape and number of vesicles and furcal development, as well as antennal chaetotaxy, more specifically the presence/absence of dorsolateral S-microchaeta on Ant IV (Queiroz and Fernandes 2011, Zon et al. 2014). Therefore, a revision of the genus is needed, along with a redescription of the type species, Fu. africana (Massoud, 1963).

According to Massoud (1967), Fu. africana has no eyes and no body pigments but has a well-developed furca. Regarding these characteristics, until now, Fu. emucronata Zon et al., 2014 was the only species similar to Fu. africana, except for the absence of mucro. In this sense, the new species Fu. boiuna sp. nov. represents the third in the genus without eyes and body pigment.

In relation to these three species, the most remarkable similarity among them is: the presence of a somewhat swollen branch of mandible and two basal strong teeth, although some minor differences can be observed in the total number of apical teeth. Furculanurida boiuna sp. nov., together with Fu. emucronata, has seven teeth on the mandible and the ungues exhibit a tooth on their inner edge, while Fu. africana mandible has nine teeth and the ungues are devoid of teeth.

Despite the mentioned similarities, Fu. boiuna sp. nov. shows a complete furca, while in Fu. emucronata it is incomplete, without mucro. Moreover, Fu. emucronata has 7 S-chaetae on Ant IV and between 13–16 vesicles on PAO of an elliptical shape, while Fu. boiuna sp. nov. shows 6 S-chaetae on Ant IV and 8–9 vesicles arranged in circular shape.

From a biogeographical point of view, the fact that the Neotropical Fu. boiuna sp. nov. is the first species outside of Africa with these set of characters is of considerable relevance. This indicates that a more widespread distribution, i.e. holotropical, is possible and raises questions regarding Pseudachorutinae distribution throughout the tropics. In this sense, despite their rareness, since few specimens are known from these three species, e.g., Fu. africana is known only by the holotype, these eyeless species are important for Pseudachorutinae taxonomy.

It must be highlighted that the new species clearly fits the recently proposed Arlesia-group of genera (Queiroz and Zeppelini 2017). Except for an elongated Sgd, almost subequal to Ant IV S-chaetae, Ant III-IV chaetotaxy is doubtlessly similar to the mentioned group of genera. For example Fu. boiuna sp. nov. has trilobed apical bulb; absence of ms; presence of S1–4, S8 and S10; x chaeta between a1 and i chaeta; and apically displaced Sgd. Regarding head and thorax chaetotaxy, the pattern similarity is also evident. On head: the reduced sd chaetae, absence of c row of chaetae, as well as only p1–3 chaeta on head. On thorax: Th. I with only 2+2 chaetae; Th. II and III with one dorsolateral chaeta posteriorly displaced.

In the same sense, according to original illustrations provided by Zon et al. (2014) for Fu. emucronata, it is possible to recognize one main chaetotaxal difference from the proposed Arlesia group: the absence of one dorsolateral chaeta on Th. II and III, probably the posteriorly displaced one. However, regarding all other chaetotaxy features of Ant III-IV (S10 is interpreted as S9 by Zon et al. 2014), head (sd with fewer chaetae – sd2–5? – and c row absent) and tibiotarsi (although not drawn, M chaetae position is clearly basally displaced), it can also be placed inside the Arlesia group.

In short, as advocated by Queiroz and Fernandes (2011) and Zon et al. (2014), it should be reinforced that Furculanurida, now with 15 species (see Table 2), needs to be revised. We estimate that after such review, only these three species, Furculanurida boiuna sp. nov., Fu. emucronata and Fu. africana, would remain within the genus. However, further analyses must be made to stablish species relationships as well as their character evolution.

Figures 7–15. 

(7–9) Friesea multiclavata sp. nov. holotype male: (7) dorsal body chaetotaxy with details of clavate chaetae of Ant II, lateral head and Abd V-VI and tegumentary protuberances of Scx I of legs; (8) ventral chaetotaxy of Abd I-VI; (9) genital plate of male. (10–15) Furculanurida boiuna sp. nov. holotype male: (10) dorsal view of Ant III-IV; (11) ventral view of Ant III-IV; (12) dorsal head chaetotaxy with detail of PAO; (13) mandibles; (14) labrum; (15) labium.