Megachernes Beier, 1932

Harvey, Mark S., Ratnaweera, Pamoda B., Udagama, Preethi V. & Wijesinghe, Mayuri R., 2012, A new species of the pseudoscorpion genus Megachernes (Pseudoscorpiones: Chernetidae) associated with a threatened Sri Lankan rainforest rodent, with a review of host associations of Megachernes, Journal of Natural History (J. Nat. Hist.) 46 (41 - 42), pp. 2519-2535 : 2522-2533

publication ID	https://doi.org/ 10.1080/00222933.2012.707251
publication LSID	lsid:zoobank.org:pub:D04A3A17-A252-44A4-AD5E-4D46417F2AF1
persistent identifier	https://treatment.plazi.org/id/F44587ED-1832-A62E-137C-FD44667E6C7D
treatment provided by	Felipe
scientific name	Megachernes Beier
status

Treatment

Megachernes Beier View in CoL

Megachernes Beier 1932: 128 View in CoL ; Beier 1933: 518; Beier 1948: 476; Morikawa 1960: 144; Harvey 1991: 599; Harvey 2011, without pagination.

Type species

Chernes grandis Beier, 1930 , by original designation.

Diagnosis

Megachernes differs from other chernetid genera by the following combination of character states: posterolateral corner of coxa IV enlarged and rounded ( Figures 3 View Figure 3 , 4B View Figure 4 ); cheliceral rallum with three blades ( Figure 4F View Figure 4 ); tarsus III and IV with long tactile seta situated in middle of segment ( Figure 4G View Figure 4 ); and female spermathecae very long and T-shaped.

Megachernes kanneliyensis sp. nov.

( Figures 2–4 View Figure 2 View Figure 3 View Figure 4 )

Material examined

Holotype. Male , Kanneliya rainforest, Southern Province, Sri Lanka, 6 ◦ 09’ to 6 ◦ 18’ N, 80 ◦ 19’ to 80 ◦ 27’ E, 9 November 2006, from dorsal fur of Mus mayori pococki Ellerman, P.B. Ratnaweera ( WAM T121678 ). GoogleMaps

Paratypes. One female (with attached brood-sac) ( WAM T121679 ), two protonymphs ( WAM T121680 ), collected with holotype GoogleMaps .

Etymology

This species is named after the type locality, Kanneliya rainforest.

Diagnosis

Megachernes kanneliyensis View in CoL is the only species of the genus in which males have been described with long setae on the pedipalpal patella and chela, particularly on the prolateral surfaces, but short setae on the femur ( Figure 4C View Figure 4 ). Males of Megachernes View in CoL with long setae on the patella usually also have long setae on the femur as reported for M. afghanicus Beier, 1959 View in CoL , M. barbatus Beier, 1951 View in CoL , M. glandulosus Mahnert, 2009 View in CoL , M. limatus Hoff and Parrack View in CoL , M. loebli Schawaller, 1991 View in CoL , M. monstrosus Beier, 1966 View in CoL , M. trautneri Schawaller, 1994 View in CoL and M. tuberosus Mahnert, 2009 View in CoL ( Beier 1951, 1959, 1966, 1967; Hoff and Parrack 1958; Schawaller 1991, 1994; Mahnert 2009). Other species for which males have been described have short setae as in the majority of females. These include M. grandis ( Beier, 1930) , M. mongolicus ( Redikorzev, 1934) View in CoL , M. soriciola Beier, 1974 , M. titanius Beier, 1951 View in CoL and M. vietnamensis Beier, 1967 View in CoL ( Beier 1930, 1951, 1967, 1974; Redikorzev 1934). Of the species for which males have not been fully described or illustrated, M. kanneliyensis View in CoL is substantially larger than M. crinitus Beier 1948 View in CoL , M. himalayensis ( Ellingsen 1914) View in CoL , M. ochotonae Krumpál and Kiefer 1982 View in CoL , M. papuanus Beier 1948 View in CoL , M. pavlovskyi Redikorzev 1949 View in CoL , M. penicillatus Beier 1948 View in CoL and M. queenslandicus Beier 1948 View in CoL , which have a female pedipalpal femur length less than 1.30 mm ( Beier 1932, 1948; Redikorzev 1949; Krumpál and Kiefer 1982; Dashdamirov 2005), compared with 1.44 mm for M. kanneliyensis View in CoL . Of those species of a comparable size, M. kanneliyensis View in CoL differs as follows: the pedipalpal segments are less slender than in M. philippinus Beier, 1966 ( Beier 1966) View in CoL ; and the prolateral face of the chelal hand is only slightly curved in M. kanneliyensis View in CoL , but is noticeably curved in M. ryugadensis Morikawa, 1954 ( Morikawa 1954) View in CoL .

Description – Adults

Pedipalps, cephalothorax, abdomen and legs uniformly pale yellow ( Figures 2 View Figure 2 , 3 View Figure 3 ). Vestitural setae generally short and inconspicuous, lightly dentate; most sternal setae acicular. Pleural membrane longitudinally wrinkled striate for entire length, without setae.

Pedipalps. Robust ( Figures 2A–D View Figure 2 , 4C,D View Figure 4 ), with trochanter 1.45 (♂), 1.55 (♀), femur 2.48 (♂), 2.62 (♀), patella 2.14 (♂), 2.56 (♀), chela (with pedicel) 2.78 (♂), 3.41 (♀), chela (without pedicel) 2.54 (♂), 3.08 (♀), hand (without pedicel) 1.26 (♂), 1.44 (♀) times longer than wide; movable finger 1.12 (♂), 1.14 (♀) times length of hand. All pedipalpal surfaces finely granulate. Fixed finger with c.60 (♂), c.64 (♀) marginal teeth, movable finger with c.64 (♂), c.70 (♀) marginal teeth; accessory teeth present in distal half of fingers, fixed finger with six (♂), eight (♀) retrolateral and 12 (♂), seven (♀) prolateral teeth; movable finger with six (♂), seven (♀) retrolateral and 10 (♂), 6 (♀) prolateral teeth; fingers not gaping when closed; chelal gland pores not observable. Pedipalpal setae: male with setae on trochanter and femur small and inconspicuous, on patella and chela long and slightly curved, especially on prolateral margin ( Figure 4C View Figure 4 ); female with all setae small and inconspicuous ( Figure 4D View Figure 4 ). Fixed finger with eight trichobothria, movable chelal finger with four trichobothria ( Figure 4C,D,I View Figure 4 ); eb closer to esb than to est; est closer to et than to esb; ib and ist inserted basally; isb closer to ist than to ib; sb closer to b than to st; st closer to t than to sb. Venom apparatus only present in movable finger with nodus ramosus terminating between t and st ( Figure 4I View Figure 4 ).

Chelicerae. Hand with seven (♂, ♀) setae, including the usual five setae and two additional bs setae, all except ls and is dentate; movable finger with one acuminate seta ( Figure 4E View Figure 4 ). Galea long and stout with seven (♂), nine (♀) prominent distal rami ( Figure 4E View Figure 4 ). Rallum ( Figure 4F View Figure 4 ) composed of three blades; each dentate along anterior margin. Serrula exterior with 26 (♂), 20 (♀) lamellae. Lamina exterior present.

Cephalothorax. Carapace ( Figures 2A,C View Figure 2 , 4A View Figure 4 ) 1.09 (♂), 0.99 (♀) times longer than wide, broadest posteriorly; unicolored; eyes and eye-spots completely absent; setae small and inconspicuous, with numerous setae, including about six (♂), five (♀) setae near anterior margin, and c.59 (♂), c.62 (♀) setae on posterior disk; posterior half with two deeply incised transverse furrows, anterior furrow crosses the carapace at c.0.56 (♂), c.0.57 (♀) of carapace length, posterior furrow crosses at c.0.80 (♂), c.0.84 (♀) of carapace length; completely granulate with exception of transverse furrows. Manducatory process with one long distal and several other sub-distal setae, and with short, curved sub-oral seta; remainder of maxilla with numerous setae. Coxae ( Figures 2B,D View Figure 2 , 3 View Figure 3 , 4B View Figure 4 ) with numerous small setae over entire ventral surface, with longer setae on posterior margin of coxae IV; posterior corners of coxae IV rounded and slightly protruding but not particularly enlarged.

Abdomen. Tergites I–X and sternites V –X divided ( Figure 2 View Figure 2 ). Tergal chaetotaxy, ♂ : 44: 49: 53: 66: 68: 64: 63: 65: 48: 39: 17: 2; ♀: 62: 60: 72: 76: 74: 72: 70: 68: 54: 52: 24: 2; setae usually restricted to posterior and lateral tergal margins. Sternal chaetotaxy, ♂ : 70: (4)

61 (4): (2) 32 (2): 58: 66: 62: 60: 53: 45: 14: 2; ♀: 40: (2) 14 (2): (4) 42 (4): 66: 72: 82: 76: 72: 48: 14: 2.

Genital region. Male not studied in detail; female genitalia with anterior genital operculum with setae arranged in inverted-U, some long most short; spermathecae not observable. Brood-sac with c.24 embryos ( Figure 3 View Figure 3 ).

Legs. Legs I and II with a strongly oblique junction between femur and patella ( Figure 4H View Figure 4 ). Leg IV ( Figure 4G View Figure 4 ) with femur + patella 3.82 (♂), 3.72 (♀) times longer than broad. Tibiae of legs III and IV without tactile setae. Tarsi of legs III and IV with long tactile seta ( Figure 4G View Figure 4 ), TS = 0.59 (♂), 0.54 (♀). Tarsi with slightly raised slit sensillum. Sub-terminal tarsal setae arcuate, not dentate. Tarsal claws simple; arolium shorter than claws.

Dimensions (mm). Male holotype: body length 4.2. Pedipalps: trochanter 0.94 / 0.65, femur 1.54 / 0.62, patella 1.56 / 0.73, chela (with pedicel) 2.47 / 0.89, chela (without pedicel) 2.26, hand length (without pedicel) 1.12, movable finger length 1.25. Chelicera 0.51 / 0.27, movable finger length 0.36. Carapace 1.72 / 1.58. Leg I: femur 0.48 / 0.30, patella 0.82 / 0.29, tibia 0.68 / 0.20, tarsus 0.53 / 0.16. Leg IV: femur + patella 1.45 / 0.38, tibia 1.16 / 0.23, tarsus 0.70 / 0.19.

Female paratype. Body length 4.2. Pedipalps: trochanter 0.79 / 0.51, femur 1.44 / 0.55, patella 1.36 / 0.53, chela (with pedicel) 2.08 / 0.61, chela (without pedicel) 1.88, hand length (without pedicel) 0.88, movable finger length 1.00. Chelicera 0.39 / 0.23, movable finger length 0.30. Carapace 1.52 / 1.54. Leg I: femur 0.42 / 0.27, patella 0.75 / 0.25, tibia 0.61 / 0.19, tarsus 0.48 / 0.14. Leg IV: femur + patella 1.34 / 0.36, tibia 1.04 / 0.22, tarsus 0.65 / 0.16.

Description – protonymph

Uniformly very pale yellow, nearly white. Vestitural setae generally short and inconspicuous, lightly dentate. Pleural membrane longitudinally striate for entire length, without setae.

Pedipalps. Robust, with trochanter 1.60, femur 2.44, patella 2.12, chela (with pedicel) 3.35, chela (without pedicel) 3.10, hand (without pedicel) 1.65 times longer than wide; movable finger 0.97 times the hand (with pedicel). All surfaces of pedipalps finely granulate with exception of fingers. Fixed finger with three trichobothria, movable chelal finger with one trichobothrium ( Figure 4J View Figure 4 ); eb and ist situated basally; et situated subdistally; t medially. Venom apparatus only present in movable finger with nodus ramosus terminating slightly distal to t.

Chelicerae. With four setae on hand; movable finger without seta. Galea long and stout with seven prominent distal rami. Rallum composed of three blades.

Cephalothorax. Carapace: 0.91 times longer than wide, broadest posteriorly; eyes and eye-spots completely absent; setae small and inconspicuous, with five setae on anterior

margin, and six setae on posterior margin; shallow median furrow present, posterior furrow absent.

Abdomen. Tergites I–X and sternites II–X divided. Tergal chaetotaxy: 6: 6: 6: 6: 6: 6: 6: 6: 6: 6: T2T: 2. Sternal chaetotaxy: 0: (0) 2 (0): (1) 4 (1): 7: 6: 6: 6: 6: 6: 4: 2.

Legs. Tarsi of legs III and IV with long tactile seta, situated medially.

Dimensions (mm). Body length 1.56. Pedipalps: trochanter 0.24 / 0.15, femur 0.39 / 0.16, patella 0.36 / 0.17, chela (with pedicel) 0.67 / 0.20, chela (without pedicel) 0.62, hand length (without pedicel) 0.33, movable finger length 0.32. Carapace 0.56 / 0.61.

Remarks

Megachernes kanneliyensis is the first species of Megachernes recorded from Sri Lanka and the first pseudoscorpion recorded from the pelage of a Sri Lankan mammal. The occurrence of adult and nymphal specimens of M. kanneliyensis in the fur of Mus mayori pococki strongly suggests that the pseudoscorpions are either breeding in the pelage or in their nests and are being transported phoretically by the mouse. Species of Megachernes do not appear to be restricted to individual host species ( Table 1).

Host associations of Megachernes

Species of Megachernes are closely associated with other animals, either in the nests or fur of small mammals, nests of birds and bumblebees, or in bat guano within caves ( Tables 1, 2). The following species have been collected most frequently or exclusively in the nests or pelage of small mammals: M. barbatus , M. crinitus , M. grandis , M. himalayensis , M. kanneliyensis , M. limatus , M. monstrosus , M. ochotonae , M. penicillatus , M. philippinus , M. queenslandicus , M. soricicola , M. titanius , M. trautneri and M. vietnamensis , as well as three undescribed species from Papua New Guinea and Australia ( Table 1). This assemblage may also include M. loebli , specimens of which were sifted from leaf litter at the foot of a wall ( Schawaller 1991), a habitat that Schawaller (1991) suggested is frequently occupied by murids and that a close association with a small mammal was likely.

Three other species, M. afghanicus , M. pavlovskyi and M. ryugadensis , have been collected from guano in caves ( Table 1). Although the origin of the guano is rarely stated, deposits of bat faeces are the likely source in all cases. Two of these species have also been recorded from other habitats. Megachernes pavlovskyi has been taken from within a barn, under stones, in pigeon guano, forest litter, plant roots and rodent nests, and the subspecies M. ryugadensis myophilus differs from the other two subspecies ( M. ryugadensis ryugadensis and M. ryugadensis naikaiensis ) by its close association with other animals, having been collected on small mammals ( Rattus norvegicus and Mogera wogura ) and from nests of bumblebees. Of the remaining three species ( Table 1), M. glandulosus and M. tuberosus have been collected in caves without any mention of whether they were taken in guano ( Mahnert 2009), and M. mongolicus lacks any habitat data ( Redikorzev 1934).

M. queenslandicus Beier, 1948 Australia from Rattus fuscipes assimilis , R. fuscipes and grey scrub rat

M. ryugadensis Morikawa , Japan in bat guano in caves

1954

M. ryugadensis myophilus Japan from nest of Bombus diversus and B. ardens ; on Mogera wogura ; Morikawa, 1960 on Rattus norvegicus

M. ryugadensis naikaiensis Japan from bat guano in caves

Morikawa, 1957

M. soricicola Beier, 1974 Nepal from Soriculus nigrescens

M. titanius Beier, 1951 Vietnam from Niviventer tenaster (given as Rattus niviventer champa ), Maxomys surifer (given as R. rajah koratis ), R. sladeni sladeni ; and “from the fur of various species of rats”

M. trautneri Schawaller, 1994 Thailand from small mammal nest

M. tuberosus Mahnert, 2009 China in cave

M. vietnamensis Beier, 1967 Vietnam from Niviventer fulvescens and Rattus andamanensis (originally reported as Rattus niviventer and R. sladeni sladeni )

M. sp. indet. Papua New from nests of Micromurexia habbema (given as Antechinus Guinea habbema ) and Phascomurexia naso (given as Antechinus naso )

M. sp. nov. (Papua New Papua New from Rattus niobe , Melomys sp. and Murexechinus melanurus

Guinea) Guinea (given as Antechinus wilhelmin a)

M. sp. nov. ( Australia) Australia from Vespadelus regulus (given as Eptesicus regulus ) and Falsistrellus tasmaniensis

M. sp. nov. ( Australia) Australia from nest box of Leadbeater’s Possum ( Gymnobelideus leadbeateri )

( Beier 1948; Judson 1997)

( Morikawa 1954, 1960)

( Morikawa 1960)

( Morikawa 1957, 1960)

( Beier 1974; Martens 1975)

( Beier 1967; Judson 1997)

( Schawaller 1994) ( Mahnert 2009)

( Beier 1967; Tenorio and Muchmore 1982) ( Woolley 1989)

( Durden 1991)

( Harvey and Parnaby 1993)

∗ The host name “ Rattus ruber trimitius ” recorded by Beier (1965) appears to be a lapsus. Rattus ruber is now a synonym of R. nitidus ( Wilson and Reeder, 2005) and “trimitius” may refer to the trichozoan blood parasite Trimitus .

Phylum Chordata

Class Mammalia

Order Dasyuromorpha

Micromurexia habbema (Tate and Archbold, 1941)

Murexechinus melanurus (Thomas, 1899)

Phascomurexia naso (Jentink, 1911)

Phascogale sp.

Order Diprotodontia

Gymnobelideus leadbeateri McCoy, 1867

Order Soricomorpha

Mogera wogura (Temminck, 1842)

Soriculus nigrescens (Gray, 1842)