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Rediscovery of Lobonychium palpiplus Roewer, 1938 (Opiliones, Laniatores, Epedanidae) in Sabah, Malaysia
expand article infoChao Zhang, Jochen Martens§|
‡ Hebei University, Hebei, China
§ Institut für Organismische und Molekulare Evolutionsbiologie, Mainz, Germany
| Senckenberg Research Institute, Frankfurt am Main, Germany
Open Access

Abstract

Lobonychium palpiplus Roewer, 1938, originally reported from Indonesian Borneo, is redescribed based on the specimens from Malaysia. The genitalia of this species are described for the first time and a new genital terminology is proposed. The rediscovery expands the known distribution of the species to Malaysian Borneo.

Keywords

Arachnida, harvestmen, genitalia, functional morphology, taxonomy, Indonesia

Introduction

The monotypic epedanid genus Lobonychium Roewer, 1938 was previously known from three specimens of the nominate species L. palpiplus Roewer, 1938, collected in the area of Pontianak (Kalimantan Barat, Indonesia, island of Borneo). The species is peculiar in having seven ventral and medial setiferous tubercles on the femur of the pedipalp and basal lobes on the claw of tarsi III and IV. The types are deposited in the Naturmuseum Senckenberg, Sektion Arachnologie, Frankfurt am Main, Germany. Except for the original description, the genus and species have not been mentioned in the literature during the past eighty years.

In February 2017, the senior author was able to re-examine the type specimens. Moreover, Malaysian Borneo, to the north of the type locality, was visited in October 2015 and May 2017 and several specimens (male and female) of L. palpiplus were collected. The newly discovered Lobonychium specimens are redescribed and illustrated.

The functional morphology of the male genitalia has been elaborated in some Laniatores families, e.g., Assamiidae Sørensen, 1884; Biantidae Thorell, 1889; Fissiphalliidae Martens, 1988; Phalangodidae Simon, 1879; Podoctidae Roewer, 1912; Stygnommatidae Roewer, 1923; Zalmoxidae Sørensen, 1886, etc. (Martens 1986, 1988; Ubick and Briggs 1992; Kury and Pérez-González 2002; Schwendinger 2006; Pérez-González 2007). In order to improve the morphological knowledge of Epedanidae Sørensen, 1886 we describe for the first time the expanded and unexpanded male genitalia.

Materials and methods

Taxonomic methods follow the outline proposed by Acosta et al. (2007). The type material of Lobonychium is preserved in 70% denatured ethanol, and the specimens were examined under a Leica MZ16 at the Senckenberg Museum, Frankfurt, Germany (SMF). Non-type specimens were preserved in 75% ethanol, examined and drawn under a Leica M205A stereomicroscope. Photographs were taken using a Leica M205A stereomicroscope equipped with a DFC450 CCD. The male genitalia were placed first in hot lactic acid, then transferred to distilled water to expand the movable parts for observation (Schwendinger and Martens 2002). The terminology of genital structures follows Macías-Ordóñez et al. (2010), and the macrosetae terminology follows Kury and Villarreal (2015). Non-type material is deposited in the Museum of Hebei University, Baoding, China (MHBU). All measurements are given in mm.

Taxonomy

Epedanidae Sørensen, 1886

Epedaninae Sørensen, 1886

Lobonychium Roewer, 1938

Lobonychium Roewer, 1938: 125.

Type species

Lobonychium palpiplus Roewer, 1938, by monotypy.

Etymology

The name Lobonychium is derived from the Greek λοβός, meaning lobe of the ear, and the Latinized Greek onyx (genitive onychos), meaning claw.

Diagnosis

Body, including ocularium, unarmed. Basichelicerite and tibia II elongate. Basichelicerite dorsally with conspicuous granules. Femur of pedipalp ventrally with a row of seven setiferous tubercles. Distitarsus I with two tarsomeres, distitarsus II with three. Double claws of tarsi III–IV with basal lobes, untoothed; no scopula. Ventral plate of penis forming a heart-shaped stereoscopic structure (ventral view, Fig. 28). Glans partially sunken into dorsally depressed portion of pars distalis (Fig. 26). Stylus with capsula interna sunken into capsula externa (Fig. 27).

Sexual dimorphism

Tibia II in male distended at distal portion, but normal in female.

Remarks

Within the subfamily Epedaninae, Lobonychium is morphologically similar to Epedanidus Roewer, 1943, Metepedanulus Roewer, 1913, and Zepedanulus Roewer, 1927 in having an unarmed body. Besides, Lobonychium and Caletorellus Roewer, 1938 have characteristic basal lobes or medial branches on double claws of tarsi III–IV (Roewer 1938: 125, 129, fig. 4 b–d). However, Lobonychium is noticeably distinct from these epedanids by the pedipalp femur, medially with a row of seven setiferous tubercles.

Distribution

The type locality is at or near the city of Pontianak (Fig. 36 A), Indonesia. The new records are from Malaysia, at Trus Madi Mountain (Fig. 36 B) and Kalabakan (Fig. 36 C).

Lobonychium palpiplus Roewer, 1938

Figs 1–7, 8–22, 23–30, 31–34, 36

Lobonychium palpiplus Roewer, 1938: 125, fig. 44.

Type specimens

Male lectotype (SMF-5376-1201), here designated, labeled: “Lobonychium palpiplus, male lectotype (SMF-5376-1201), designated by Chao Zhang [handwritten]”.

All types (lectotype and two paralectotypes) from Pontianak [00°01'S, 109°20'E], Borneo (West Kalimantan, Indonesia), deposited in the Senckenberg Museum Frankfurt, Germany, labeled: “Arachn. Coll. Roewer – Lfd. No. 5376, Opil: Epedaninae No. 16, Lobonychium palpiplus Rwr [abbreviation for Roewer], 2♂1♀, Borneo: Pontianak, Typus, Roewer det. 1935” (Fig. 35) (examined).

Additional material examined. 1♂ (MHBU-Opi-20151208m) and 2♀, (MHBU-Opi-20151208f, MHBU-Opi-2015120801f), Malaysia: Sabah, Trus Madi Mountain, about 1103 m alt. 05°25.637'N, 116°25.984'E, October 9, 2015, Z. Z. Gao leg.; 1♀, Malaysia: Sabah, Trus Madi Mountain, about 1081 m alt. 05°26.111'N, 116°27.237'E, October 10, 2015, Z. Z. Gao leg.; 1♀, Malaysia: Sabah, Trus Madi Mountain, about 760 m alt. 05°27.598'N, 116°26.936'E, October 12, 2015, Z. Z. Gao leg.; 1♀, Malaysia: Sabah, Kalabakan, about 330 m alt. 04°32.522'N, 117°10.020'E, October 18, 2015, Z. Z. Gao leg.; 2♀, Malaysia: Sabah, Trus Madi Mountain, about 1121 m alt. 05°26.529'N, 116°27.309'E, May 1, 2017, C. Jin leg.; 1♂1♀, Malaysia: Sabah, Trus Madi Mountain, about 1081 m alt. 05°26.111'N, 116°27.237'E, May 3, 2017, C. Jin leg.

Redescription

Male (MHBU-Opi-20151208m) habitus as in Figs 1, 8–9, 31. Coloration (Fig. 31): entire body rusty yellow, with somewhat dark brown to blackish brown patches on dorsum; median area of carapace with dark brown reticulations; both lateral ridges of scutum with blackish brown stripes; opisthosomal region of scutum banded with a dark brown outline; a dark brown band across posterior margin of scutum; free tergites I–III each with a dark brown band; coxa with dark brown reticulations; free sternites with transverse dark brown band; chelicerae and pedipalp reticulated; trochanters of all legs pale yellow, femur, patella, tibia and metatarsus with black reticulations, tarsus lighter.

Figures 1–7. 

Lobonychium palpiplus Roewer, 1938, male (MHBU-Opi-20151208m) (1–6), female (MHBU-Opi-20151208f) (7) 1 Body, lateral view 2 Left chelicera, medial view 3 Same, ectal view 4 Cheliceral fingers, frontal view 5 Basal segment of left chelicera, dorsal view 6 Left pedipalp, medial view 7 Right pedipalp, medial view. Scale bars: 1mm (1, 6–7); 0.5 mm (2–3, 5); 0.25 mm (4).

Dorsum (Figs 8, 31). Scutum elongate in appearance, both sides straight, nearly parallel, widest portion of body at scutal area IV, abdomen bluntly pointed posteriorly. Carapace unarmed on lateral portion of anterior margin. Surface of dorsum smooth. Ocularium low and oval, unarmed, removed from anterior border of scutum by 0.16 mm. Borders of opisthosomal scutum parallel to each other. Free tergites and anal operculum unarmed.

Figures 8–22. 

Lobonychium palpiplus Roewer, 1938, male (MHBU-Opi-20151208m) (8–16), female (MHBU-Opi-20151208f) (17–22) 8 Body, dorsal view 9 Same, ventral view 10 Right tarsus I, retrolateral view 11 Distal segment of right tarsus III, retrolateral view 12–15 Patellae and tibiae of left legs, prolateral view 12 Leg I 13 Leg II 14 Leg III 15 Leg IV 16 Basal segment of right chelicera, dorsal view 17 Body, dorsal view 18 Right chelicera, ectal view 19 Cheliceral fingers, frontal view 20 Basal segment of left chelicera, ectal view 21 Patella and tibia of left leg II, prolateral view 22 Ovipositor, ventral view. Scale bars: 1 mm (8–9, 12–15, 17, 21); 0.5 mm (10, 16, 18, 20); 0.25 mm (11, 19, 22).

Venter (Fig. 9). Surface of coxa I tuberculated, antero-dorsally with a coarse tubercle, and a row of five tubercles on ventral surface. Coxa II with a row of small granules on ventral surface. Coxae III and IV nearly smooth aside from a row of small teeth on front and rear margins of coxa III. Genital operculum and free sternites with seta-tipped granules. Spiracles clearly visible.

Chelicerae (Figs 2–5, 16). Basichelicerite elongate, with a slight bulla and armed with two conspicuous granules at base of bulla, medial surface with a basal protuberance (Figs 2, 3, 5). Cheliceral hand with some greater seta-tipped tubercles. Fingers relatively short, inner edges toothed (Fig. 4): moveable finger and fixed finger with eight crested teeth, respectively.

Pedipalpi (Fig. 6). Coxa dorsally with one small tubercle near distal margin. Trochanter ventrally with one setiferous tubercle and dorsally with one small tubercle. Femur ventrally with a row of seven setiferous tubercles of even size and spirally arranged from base to distal end on medial side; dorsally with many low conical tubercles along entire length. Patella ventro-mesally with two long and one short setiferous tubercles, and ventro-ectally with one long and one short setiferous tubercles. Tibia ventro-mesally with three setiferous tubercles, and ventro-ectally with four setiferous tubercles. Tarsus with three setiferous tubercles on each side of ventral surface. Tarsal claw curved, approximately same length as tarsus.

Legs (Figs 10–15). Slender and long. All segments unarmed, nearly smooth. Femora I–IV not curved, almost straight. Tibia II distended at distal portion, conspicuously longer than tibiae I, III and IV (Figs 12–15). Distitarsus I with two (Fig. 10), distitarsus II with three tarsomeres. Distitarsi III–IV without scopula. Each claw of tarsi III–IV with one basal lobe nearly circular in shape (Fig. 11). Tarsal formula (I–IV): 7/19/7/7.

Penis (Figs 23–30). Shaft slender, nearly parallel-sided, then distended towards apical portion (pars distalis). Ventral plate inflated, hollow on inner side, forming a heart-shaped stereoscopic ventral frame (ventral view, Fig. 28) (Figs 27, 30). Glans partially sunken into dorsal depressed portion of pars distalis (Fig. 26). Prior to inflation of capsula externa (follis) (Fig. 30), stylus with capsula interna sunken into capsula externa (Fig. 27). Capsula externa dorsally and ventrally extended at distal end. Everted capsula interna with a bifurcate ventral lobe distally. Stylus finger-shaped. Spination symmetrical. One pair of setae A, C, D, and E. Two pairs of setae F. Four pairs of setae B (Figs 28–30).

Figures 23–30. 

Lobonychium palpiplus Roewer, 1938 (MHBU-Opi-20151208m) 23 Penis, ventral view 24 Same, dorsal view 25 Same, lateral view 26 Distal part of penis, lateral view 27 cross-section through glans and truncus at the marked point 28 Distal part of penis (expanded), ventral view 29 Same, dorsal view 30 Same, lateral view. Abbreviations: CE capsula externa (follis) CI capsula interna G glans S stylus VF ventral frame. Scale bars: 0.25 mm.

Female (MHBU-Opi-20151208f) (Figs 7, 17–22, 32–34). Generally similar to male except abdomen slightly wider than in male (Figs 17, 32). Tibia II conspicuously longer than tibiae I, III and IV, but inconspicuously distended distally (Fig. 21). Inner edges of finger of chelicera toothed (Fig. 19): moveable finger with 12 teeth; fixed finger with seven teeth. Tarsal formula (I–IV): 7/22/7/7.

Figures 31–34. 

Lobonychium palpiplus Roewer, 1938 Photographs of male (MHBU-Opi-20151208m) and female (MHBU-Opi-20151208f) 31 Male body and parts of appendages, dorsal view 32 Female body and parts of appendages, dorsal view 33 Same, lateral view 34 Same, ventral view. Scale bars: 1 mm (Fig. 33); 0.5 mm (Figs 31–32, 34).

Ovipositor (Fig. 22). Ventral surface with four setae and dorsal surface with six setae.

Measurements

Male (female): body 1.89 (2.74) long, 1.36 (1.64) wide at widest portion, scutum 1.69 (1.76) long. Ocularium 0.19 (0.20) long, 0.37 (0.35) wide. Proximal article of chelicera 0.69 (0.62) long, 0.24 (0.23) wide; second 0.89 (0.98) long, 0.26 (0.26) wide; distal 0.40 (0.44) long, 0.09 (0.08) wide. Pedipalp claw 0.64 (0.63) long. Penis 0.88 long. Measurements of pedipalp and legs as in Tables 1, 2.

Pedipalp and leg measurements (mm) of Lobonychium palpiplus Roewer, 1938, male, length/width.

Trochanter Femur Patella Tibia Metatarsus Tarsus Total
Pedipalp 0.32/0.28 1.47/0.20 0.97/0.19 0.77/0.18 0.71/0.14 4.24
Leg I 0.35/0.18 1.72/0.14 0.46/0.18 1.38/0.11 2.21/0.05 1.33/0.03 7.45
Leg II 0.36/0.18 3.34/0.10 0.66/0.18 2.99/0.17 3.75/0.05 2.80/0.04 13.90
Leg III 0.37/0.24 2.20/0.15 0.64/0.25 1.23/0.17 2.63/0.10 1.24/0.07 8.31
Leg IV 0.37/0.24 2.90/0.15 0.61/0.25 1.52/0.17 3.56/0.10 1.44/0.07 10.40

Pedipalp and leg measurements (mm) of Lobonychium palpiplus Roewer, 1938, female, length/width.

Trochanter Femur Patella Tibia Metatarsus Tarsus Total
Pedipalp 0.45/0.31 1.49/0.18 1.10/0.22 0.91/0.19 0.89/0.12 4.84
Leg I 0.37/0.19 1.62/0.10 0.48/0.18 1.36/0.10 2.20/0.06 1.34/0.04 7.37
Leg II 0.39/0.20 3.18/0.10 0.62/0.18 3.01/0.10 3.72/0.06 2.73/0.04 13.65
Leg III 0.42/0.26 2.13/0.12 0.54/0.26 1.28/0.16 2.54/0.09 1.10/0.06 8.01
Leg IV 0.42/0.26 2.88/0.12 0.54/0.26 1.61/0.16 3.41/0.09 1.43/0.06 10.29

Habitat

The specimens were collected by leaf litter sieving in dark moist places under dense forest canopy.

Variation

The collection examined contains ten specimens, two males and eight females. The male (MHBU-Opi-20151208m) and the female (MHBU-Opi-20151208f) described here are asymmetrical in the position of granules on the left (Figs 5, 20) and right (Figs 16, 18) basichelicerites of chelicerae. Another male body 1.96 long, 1.21 wide at the widest portion, scutum 1.68 long. Size range of other females (n=7) as follows minimum (maximum in parentheses): body 2.20 (2.70) long, 1.59 (1.76) wide at the widest portion, scutum 1.72 (1.89) long. The variations in the number of segments in the tarsus are shown in Table 3.

Numbers of tarsomeres of on legs of Lobonychium palpiplus Roewer, 1938. L left, R right tarsus. Only one number is given when the specimen is symmetrical.

Specimen number (n=10) Sex Leg I Leg II Leg III Leg IV
1 male 7 L19, R 21 7 7
2 female 7 L19, R 20 7 7
3, 4 male and female 7 19 7 7
5, 6 females 7 22 7 7
7, 8 females 7 18 7 7
9 female 7 L18, R 21 6 7
10 female 7 21 7 7

Distribution

Indonesia (Pontianak), Malaysia (Trus Madi Mountain, Kalabakan).

Remarks

The three type specimens have not been dissected and are in good condition, with all appendages attached. The original description of the types by Roewer (1938) corresponds more-or-less to the morphology of the type specimens except for few minor characters, e.g., the male tibia II is distended at its distal portion, the presence of one short setiferous tubercle ventro-mesally on the pedipalpal patella, the minimum numbers of the tarsomeres II and III are 18 and 6, respectively, and the smaller male body (1.89–1.96).

Additionally, the localities of the new records from Malaysia are at most about 120 km apart. The distance between the recorded type locality (Indonesian part of Borneo) and the new localities (Malaysian part) is nearly 1000 km (Fig. 36).

Figure 35. 

Original label with Roewer’s handwriting of the type series of Lobonychium palpiplus Roewer, 1938.

Figure 36. 

Distribution of Lobonychium palpiplus Roewer, 1938 in Borneo. A type locality B Trus Madi Mountain C Kalabakan.

According to the drawings presented by Suzuki (1969: 30, fig. 19 E; 1977: 19, fig. 6 F–G; 1981: 268, fig. 1B–C) the male genital morphology of Epedanidae seems to be quite homogeneous and little functional variation has been documented to date.

Acknowledgements

We thank Peter Jäger, Julia Altmann, Lukas Keine, and Lea Wolter for their very kind attention during one of the author’s (CZ) visit to the SMF. Many thanks are due to Zhizhong Gao and Chi Jin for collecting the specimens. This work was supported by the National Natural Science Foundation of China (No. 31471956), and the researcher alumni network Senckenberg, Frankfurt am Main, Germany (FANS). Adriano B. Kury and Gonzalo Giribet provided insightful criticism to the draft. Chris Glasby kindly checked the English style and wording. We heartily thank them for their valuable help.

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