Pectenobunus Roewer, 1910

Tourinho-Davis, Ana Lúcia, 2004, The third South American species of the genus Pectenobunus Roewer, with a new synonymy for the genus (Opiliones, Eupnoi, Sclerosomatidae, Gagrellinae), Zootaxa 405 (1), pp. 1-16 : 4-7

Pectenobunus Roewer, 1910

Opilio [part]: Canestrini 1888: 105–106.

Pectenobunus Roewer 1910: 157 ; 1923: 1063; Mello­Leitão 1932: 18; 1938: 321; Roewer 1953: 185; Ringuelet 1954: 297–298; 1959: 16; Capocasale 1967: 28; Cokendolpher & Hunt 1993: 1–2; Crawford 1992: 38.

Caiza Roewer 1925: 32 ; Mello­Leitão 1932: 18; 1938: 322; Roewer 1953: 185, Ringuelet 1954: 287–288; 1959: 217; Crawford 1992: 14. [type species is Caiza colliculosa Roewer, 1925 , by monotypy]. syn. nov.

Acropiliops Mello­Leitão 1933: 99 ; 1938: 319; Crawford 1992: 11. Synonymy established by Cokendolpher & Hunt 1993.

Type species. Pectenobunus paraguayensis ( Canestrini, 1888) by original designation.

Included species. P. colliculosus (Roewer) , P. paraguayensis (Canestrini) and P. ruricola (Mello­Leitão) .

Former diagnoses (each character is numbered and referred to in a subsequent paragraph):

Roewer, 1923 — Eye mound as wide as long (1.1), with one to five spines with three points each (1.2). Dorsum unarmed (2); femur II approximately two times longer than the body, femora I and III approximately as long as the body; femur II with 2 nodules, I, III and IV without nodules (4). Coxae armed with relatively short three­pointed denticles (6), legs relatively short (9) and thin.

Roewer, 1953 — Eye mound with two rows of four to five spines (1.2), abdominal scute evenly curved, unarmed (2); Femur with 0/2/0/0 nodules (3); femora I and III shorter than body (4).

Ringuelet, 1954 — Eye mound with two rows of high spines divergent and variable from three to six, each one with two to four small apical points (1.2). Dorsum unarmed (2). Nodules 0/2/0/0, femur II may have less than two or none: I/2, I/I, I/0 or 0/0 (3). Femora relatively short, I to III about equal, II between 1.5 to 2.3 times, IV around 1.5 the length of the body: a little shorter in females (4). Tegument with reticulations forming alveoli (5). Coxae armed with sharp tri­pointed denticles (6).

Ringuelet, 1959 — Eye mound armed with two rows of high divergent spines ending in 2, 3 or 4 small apical points (1.2). Dorsum unarmed (2). Femora I and III from a little shorter to a little longer than the body, femur II from 1.5 to two body length, formula: (♂) 0.9 to 1.3/1.5 to 2.3/0.9 to1.3/13 to 1.9, (♀) 0.8 to 1.1/1.5 to 1.8/0.8 to 1.0/1.2 to 1.4 (4). Tegument with reticulations forming alveoli (5). Coxae: teeth with three sharp points (6).

Cokendolpher & Hunt, 1993 — Eye mound with four to seven tubercles (each tipped with three to four spines) (1b), presence of two pseudoarticular nodules in femora II (nodules lacking in other femora) (3), femora I equal to or slightly longer (up to 1.5 times) than body (4), abdomen without median spines or tubercles (2), male palpal tarsi lacking ventral rows of denticles (7), penis with a small narrow alate portion (8).

Comments on the characters used in the former diagnoses:

(1.1) (6) These states and (7) (8) characters are widespread in Neotropical Gagrellinae and of limited use for a diagnosis.

(1.2) Spines and tubercles are also found in species of Holmbergiana , Guaranobunus and Parageaya . In Holmbergiana they are as shorter as in P. ruricola , and possess three or more small points each, in Guaranobunus they have the same number, shape and length as P. colliculosus and P. paraguayensis and in Parageaya the eye mound varies from unarmed to armed.

(2) This character is applicable to all Neotropical species of Gagrellinae , however it does not match the species of Pectenobunus . P. colliculosus , P. paraguayensis and P. ruricola have these processes or tubercles in different sizes in abdominal scute ( Figs. 7, 8, 9 ). They are very subtle in P. ruricola , almost imperceptible ( Fig. 9 ), while much more developed in P. colliculosus ( Fig. 7 ) and intermediate in P. paraguayensis ( Fig. 8 ). One projection in the frontal margin of the abdominal scute is found in two species of Holmbergiana , the only species of Guaranobunus and the type species of Parageaya – Parageaya ciliata . The presence of the armature in the abdominal scute supports the tribe Gagrelleae and it may be a convergence in Pectenobunus , Holmbergiana , Guaranobunus and Parageaya ciliata .

The tribes Gagrelleae and Zalepteae were established by Roewer (1954, 1955), this dichotomy was based upon two states of the same external character, presence or absence of spines on the abdominal scute. Following the concept of Roewer the New World Gagrellinae were recognized mainly by the absence of spines on abdominal scute, tribe Zalepteae , and most of the Old World species (tribe Gagrelleae ) by the presence of one or more spines. It seems that Roewer did not consider in his analysis the well developed spines present on the abdominal scute of his Caiza colliculosa , much as he did with the protuberances shown in species of Pectenobunus , Holmbergiana and Parageaya . Martens (1987) presented several illustrations of Old World species without any spine or protuberance on the ventral surface of the body. As what happens with most of the New World Gagrellinae the systematics of Old World is as confused, if not more chaotic than it is in their American counterparts. Since Roewer’s publications the groups of species placed together in Old World genera have never been subject of systematic revisions. However a large number of new taxa have been described in the last years according with the Roewerian system ( Suzuki 1963, 1969, 1970, 1977a, 1977b). The only work presenting detailed descriptions for both external and genital mophology, and discussion of the genital patterns among the Old World species ( Gagrelleae included) were done by Martens (1987) for the Nepalese species. However for his work Martens did not revise the genus Gagrella (the type genus of the subfamily), gave descriptions or discussed the characters of the penis shared by the species within this genus. Martens studied and described a large number of species of Gagrella , although examining the illustrations given in the paper it can be noted that the species did not share external or genital similarities suggesting a closer relationship among them, or supporting this group as monophyletic. On the opposite there is high variety of size and shape in the stylus, glans (including the angle formed by shaftglans), winglets, and shaft among the Gagrella species studied for the work. Knowing if the two tribes Gagrelleae and Zaleptinae make sense for the modern concept and study in Opiliones will depend upon systematic revisions refining descriptions, illustrations, studying genitalia and external morphology of Old World Gagrellinae in a deeper level.

The western South American species of Gagrellinae have some similarities with the Old World species of the same subfamily, not presently shared with the Tropical South American species. Cokendolpher (1984) commented about the closer affinities among the only one Colombian (Punta di Carmen) species of Carmenia and the eastern Asian species, including some characters present in species of other subfamilies such as Sclesomatinae. Species of Pectenobunus also share a set of characters with Asian Gagrellinae , as the presence of spines or protuberances on the abdominal scute ( Figs. 7, 8 ) and the very small sclerites present on the lateral sides of the opisthosoma ( Figs. 3, 4 ).

(3) This character may be variable even in the same species, and the same number appears in several species of Holmbergiana , variation should be included in the statement of number.

(4) This character varies in the three species thus it is ineffective for the generic diagnosis ( Table 1 ).

(5) (9) These states match the genus, but they are also present in all species attributed to Guaranobunus , Holmbergiana and Parageaya .

Emended Diagnosis. Eye mound armed with two rows of three to seven spines or shorter tubercles with three to four apical points each ( Figs. 7a–9a ; fig. 1 in Cokendolpher & Hunt 1993). Abdominal scute with one subtle protuberance, three small projections or three blunt process sharply marked in both males and females ( Figs. 7–9 ). Femoral formula: 0/0­2/0/0. Winglets of penis narrow (longer than wide), distal portion straighter without projections. Outline of winglets not very sinuous or undulated ( Figs. 10, 12, 14– 15 ; fig. 4 in Cokendolpher & Hunt 1993). Shaft forming acute angle (less than 25º) with the glans ( Figs. 11, 13 ; fig. 5 in Cokendolpher & Hunt 1993). Transverse section of glans elliptical. Stylus short (20% the length of glans) ( Figs. 14–15 ; fig. 4 in Cokendolpher & Hunt 1993).

Distribution. Southern Brazil, Bolivia, Paraguay, Uruguay and Northeastern Argentina ( Fig. 16 ).

Figures

FIGURE 16. Western South America showing distribution of the three nominal species of Pectenobunus Roewer. P. paraguayensis (triangles), P. ruricola (square), P. colliculosus (circles). This map includes Paraguay, Uruguay, part of Argentina, Bolivia and Brazil. Dotted lines = countrys and state boundaries, thin lines = rivers.

FIGURES 6–9. Fig. 6. P. colliculosus (Roewer). Male (SMF RII/346/144). 6, right pedipalp, lateral view. Scale bar = 1.0 mm. Figs 7–9. Schematic view of Pectenobunus species showing (by the arrows) the armature of the eye mound and the variation in protuberances on the abdominal scute. 7–7a, P. colliculosus; 8–8a, P. paraguayensis; 9–9a, P. ruricola, protuberance indicated by the arrow.

FIGURES 1–5. Pectenobunus colliculosus (Roewer). (paratypes SMF RII/346/144). Male: 1, dorsal view; 1a, detail showing the sculpture of the tegument; 3, male, lateral view; 5, right chelicerae showing ventrobasal spine in the detail; Female: 2, dorsal view; 4, lateral view. Scale bars = 1.0 mm for Figs 1–4; = 0.5 mm for Fig 5.

FIGURES 10–15. Figures 10–11, 14. P. colliculosus. Male (SMF RII/346/144), Penis, 10, ventral view; 11. lateral view; 14, anterior half, ventral view. Figures 12–13,15. P. paraguayensis. Male, (SMF R I/4/573), penis, 12, ventral view; 13, lateral view; 15 anterior half, ventral view. Scale bars = 0.5 mm for Figs 10–11, 12–13; = 0.25 mm for Figs. 14–15.