Species of Brachystomella ( Collembola : Brachystomellidae ) from the Neotropical region

In this paper six new species o f the genus Brachystomella Agren from the Neotropical region are described : B. desutterae sp. n. (Peru), B. mataraniensis sp. n. (Peru), B. pefauri sp. n. (Venezuela), B. purma sp. n. (Peru), B. saladaensis sp. n. (Argen­ tina) and B. zerpa sp. n. (Venezuela). Brachystomella honda Christiansen & Bellinger, 1988 is synonymised with Brachystomella baconaoensis Gruia, 1983. Diagnoses and comments on the original descriptions as well as remarks on 22 species are included.


INTRODUCTION
revised the list of species of the genus Brachystomella, which currently includes 52 spe cies, out of which 25 occur in the Neotropical region.In the Catalogue of Neotropical Collembola by Mari Mutt & Bellinger (1990) there are 29 species of Brachystomella.However, this list was assembled from the literature without critical evaluation of the species.B. allendei Massoud & Rubio (in Hermosilla & Rubio, 1976) is nomen nudum.Specimens from this region determined as B. parvula, with the "parvula" type of furca, should be called B. ca.parvula (Schaeffer, 1896).B. rosai (Bonet, 1934) belongs to the genus Setanodosa Salmon.B. trinitata (Jackson, 1927) (probably = B. septemoculata Denis, 1931) was identified on the basis of immature specimens (Massoud, 1967).B. subandinensis Massoud, 1967 is a new synonym for B. contorta Denis, 1931.Two other species should also be mentioned, as they may belong to the genus Brachystomella.These are: Pseudachorutes asper Borner, 1906, described from Brasil and Schoettella subcrassa Schaffer, 1897, described from Argentina.However, at present it is not possible to resolve this problem, because the type mate rial has been lost (Strumpel, personal comm.).
In the material from Argentina, Peru and Venezuela we found six new species, which are described below.We also examined the types and additional material of 22 spe cies, commented on the original descriptions and pro vided some additional remarks.We were not able to examine one species: Brachystomella sexoculata Mas soud, 1967 because the type material was not preserved.We also synonymised Brachystomella honda Christiansen & Bellinger, 1988 with Brachystomella baconaoensis Gruia, 1983.This study confirms that most of the species of Bra chystomella occur the Neotropical region (Najt & Weiner, 1996).
Redescription.Antennae shorter than head (about 3/4 the length of head).Antennal segment I with 7 setae, antennal segment II with 12-13 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sen sory organ of antennal segment III consisting of: two small globular internal sensilla, two subcylindrical guard sensilla (both the same size) and one guard seta between them; ventral microsensillum present.Antennal segment IV with rather short ordinary setae, with 5 only slightly distinct subcylindrical sensilla; dorsoexternal microsen sillum present, truncated subapical organite present; apical vesicle simple in a deep cavity, ventral side with a few truncated setae (Fig. 3).

Brachystomella contorta
Redescription.Antennae shorter than head (about 3/4 the length of head).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sensory organ of antennal segment III consisting of: two small globular internal sensilla, two subcylindrical guard sensilla (dorsolateral sensillum shorter than ventrolateral one) and two guard setae between them; ventral microsensillum present.Antennal segment IV with rather short ordinary setae, with 6 slightly distinct subcylindrical sen silla; dorsoexternal microsensillum present, truncated subapical organite present; apical vesicle simple in deep cavity, ventral side with a few truncated setae.(Fig. 9).

Brachystomella cyanea
Redescription.Antennae shorter than head (about 3/4 the length of head).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sensory organ of antennal segment III consisting of: two small globular internal sensilla, two subcylindrical guard sen silla (both of the same size) and two guard setae between them; ventral microsensillum present.Antennal segment IV with rather long ordinary setae, with 6 slightly distinct subcylindrical sensilla; dorsoexternal microsensillum pre sent, truncated subapical organite present; apical vesicle simple in deep cavity, ventral side with a few truncated setae (Fig. 16).
Antennae shorter than head (about 3/4 the length of head).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ven tral separation well marked.Sensory organ of antennal segment III consisting of: two small globular internal sensilla, two guard sensilla subcylindrical (both of the same size) and two guard setae between them; ventral microsensillum present.Antennal segment IV with ordinary setae and 6 subcylindrical sensilla; dorsoextemal microsensillum, subapical organite present; apical vesicle trilobated, ventral side with a few blunt setae (Fig. 22).
Tibiotarsi I, II and III with 19, 19 and 18 setae, respectively, with acuminate distal setae, seta M present, seta B7 absent on tibiotarsus III.Femora I, II and III with 11,11 and 10 setae, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 1 and 1 setae, subcoxae " 1" I, II and III with 1, 2 and 2 setae, respectively.Claw with inner tooth at half length of its inner edge, with pair of lateral teeth (Fig. 24).Empodial appendage absent.Discussion.The new species is closest to B. contorta Denis, 1931.Both species share the same characters: absence of setae a0, on the head, 2+2 setae on the thoracic tergum I, the same number of setae on the dens (5), the same number of setae on tibiotarsi (19,19,18).They differ in the shape of the apical vesicle (simple in B. contorta and trilobated in the new species), in the number of setae on femora I (12 in B. contorta and 11 in the new species), in the number of setae on subcoxae "2" II and III (2, 2 in B. contorta and 1, 1 in the new species), in the number of setae hr on the even anal valves (two on each valve in B. contorta and one in the new species).

Brachystomella globulosa
Redescription.Antennae shorter than head (about 3/4 the length of head).Antennal segment I with 7 setae, antennal segment II with 11-12 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sen sory organ of antennal segment III consisting of: two small internal sensilla globular distally, two subcylin drical guard sensilla (dorsolateral sensillum somewhat shorter than ventrolateral one) and two guard setae between them; ventral microsensillum present.Antennal segment IV with rather long ordinary setae, with 6 only slightly distinct subcylindrical sensilla; dorsoexternal microsensillum present, truncated subapical organite pre sent; apical vesicle slightly trilobated in deep cavity, ven tral side with a few truncated setae.(Fig. 28).
Antennae shorter than head (about 3/4 length of head).Antennal segment I with 7 setae (sometimes asymmetrical: 6 or 8 on one antenna), antennal segment II with 12 setae (also asymmetrical: 11 or 13 setae).Antennae III and IV fused dorsally, ventral separation well marked.Sensory organ of antennal segment III con sisting of: two small globular internal sensilla, two rather short subcylindrical guard sensilla (both of the same size) and two guard setae between them; ventral microsen sillum present.Antennal segment IV with rather short ordinary setae, with 6 distinct subcylindrical sensilla; dor soexternal microsensillum present, truncated subapical organite present; apical vesicle simple, ventral side with a few blunt setae (Fig. 35).
Tibiotarsi I, II and III with 19, 19 and 18 setae, respec tively, with acuminate distal seta; seta M in row B, seta B7 absent on tibiotarsus III.Femora I, II and III with 12, 11 and 10 setae, trochanters I, II and III with 5, 5 (asym metry: 3 or 4), and 4 setae, coxae I, II and III with 3, and 7 setae, subcoxae "2" I, II and III with 0, 2 and setae, subcoxae "1" I, II and III with 1, 2 and 2 setae, respectively.Claw with inner tooth at half length of its inner edge, with pair of lateral teeth (Fig. 37).Empodial appendage absent.Discussion.Of the species of Brachystomella, with four vesicles in the postantennal organ, the new species is closest to Brachystomella victoriensis from Argentina (Izarra, 1972).The two species differ in the shape of the apical vesicle (trilobated in the new species and simple in B. victoriensis), in the number of setae on femora I, II and III (12, 11 and 10 in the new species and 13, 12 and 11 in B. victoriensis), and in the presence of two long setae curved at the tip on the tibiotarsi in B. victoriensis.Thibaud & Massoud, 1983 Remarks.This species has the maxilla typical for the genus (not as in Thibaud & Massoud, 1983: Fig. 1B); however, the distal tooth is very prominent.The entire type material is badly preserved and therefore we are unable to comment more extensively.Palacios-Vargas & Najt, 1981 Remarks.Sensory organ of antennal segment III with two guard setae between guard sensilla.Tibiotarsi I, II and III with 18, 18 and 17 setae, respectively, of which 3, 4 and 4 capitate (not 4, 4 and 4 as in the original descrip tion by Palacios-Vargas & Najt, 1981); A1, A7, T2 capi tate on tibiotarsus I, setae A1, A2, A7, T2 capitate on tibi otarsi II and III, seta M absent, seta B7 absent on tibio tarsus III.Femora I, II and III with 12, 11 and 10 setae, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 2 and 2 setae, subcoxae " 1" I, II and III with 1, 2 and 2 setae, respectively.Even anal valves each with three setae hr.Najt & Palacios-Vargas, 1986 Remarks.Sensory organ of antennal segment III with two guard setae between guard sensilla, ventral sensillum longer than dorsal one.Tibiotarsi I, II and III with 19, 19 and 18 setae, respectively (not 18, 18 and 17 as in the original description by Najt & Palacios-Vargas, 1986); seta M present, seta B7 absent on tibiotarsus III.Femora I, II and III with 12, 11 and 9 setae, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 2 and 2 setae, sub coxae " 1" I, II and III with 1, 2 and 2 setae, respectively.Even anal valves each with one seta hr.Rubio & Najt, 1979 Remarks.Sensory organ of antennal segment III with two guard setae between guard sensilla.Tibiotarsi I, II and III with 19, 19 and 18 setae, respectively (not 15, 15 and 14 as in the original description by Rubio & Najt, 1979); seta M present, seta B7 absent on tibiotarsus III.Femora I, II and III with 12?, 11 and 10 setae, trochanters 1, II and III with 5, 5 and 4 setae, coxae I, II and III with 2, 3 and 3 setae, subcoxae "2" I, II and III with 0, 1 and 1 setae, subcoxae " 1" I, II and III with 1, 2 and 2 setae, respectively.Even anal valves each with three setae hr.(Scott, 1960) Neanurodesneomexicanus Scott, 1960Brachystomella arida Christiansen & Bellinger, 1980 Remarks. Sensory organ of antennal segment III with two guard setae between guard sensilla.Tibiotarsi I, II and III with 18, 18 and 17 setae, respectively; seta A1 slightly capitate, seta M absent, seta B7 absent on tibio tarsus III.Femora I, II and III with 12, 11 and 10 setae, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 2 and 2 setae, subcoxae " 1" I, II and III with 1, 2 and 2 setae, respectively.Even anal valves each with three setae hr.
Antennae shorter than head (about 3/4 length of head).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sensory organ of antennal seg ment III consisting of: two small globular internal sensilla, two subcylindrical guard sensilla (both of the same size) and two guard setae between them; ventral microsensillum present.Antennal segment IV with ordi nary setae and 6 subcylindrical sensilla; dorsoexternal microsensillum, subapical organite present; apical vesicle slightly trilobated, ventral side with a few truncated setae (Fig. 41).
Antennae shorter than head (more than 3/4 length of head).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ven tral separation well marked.Sensory organ of antennal segment III consisting of: two small curved internal sen silla, two subcylindrical guard sensilla (dorsolateral sensillum shorter than ventrolateral one) and two guard setae between them; ventral microsensillum present.Antennal segment IV with ordinary setae, with 6 distinct subcylin drical sensilla; dorsoexternal microsensillum, subapical organite present; apical vesicle trilobated, ventral side with a few blunt setae (Fig. 47).
Tibiotarsi I, II and III with 19, 19 and 18 setae, respec tively, with acuminate distal setae, with seta M present between setae B4 and B5, seta B7 absent on tibiotarsus III.Femora I, II and III with 12, 11 and 10 setae, respec tively, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 1 and 1 setae, subcoxae " 1" I, II and III with 1, 2 and 2 setae, respectively.Claw with inner tooth in the middle of its inner edge, with a pair of lateral teeth (Fig. 50) .Empodial appendage absent.Discussion.The new species is closest to B. agrosa Wray, 1953 described from Puerto Rico.They possess the same number of vesicles in postantennal organ (4), the same number of setae on thoracic tergum I (2+2), the same number of setae on the dens (5), the same sensillar formula (022/21111), the same number of setae on tibio tarsi I, II and III (19,19 and 18) and seta a0 on the head.The two species differ in the shape of the apical vesicle on antennal segment IV (simple in B. agrosa and trilo bated in the new species), in the number of setae hr (two setae in B. agrosa and one seta in the new species), and in size (1-1.5 mm for B. agrosa and 0.47-0.65 mm for the new species).Najt, 1973 Remarks.Sensory organ of antennal segment III with two guard setae between guard sensilla, dorsolateral sensillum somewhat shorter than ventrolateral one.Tibiotarsi I, II and III with 19, 19 and 18 setae, respectively; setae A1, A2, A4, A5, A7, B4 and B5 slightly capitate; seta M present, seta B7 absent on tibiotarsus III.Femora I, II and III with 13, 12 and 11 setae, trochanters I, II and III with 6, 6 and 6 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 2 and 2 setae, subcoxae "1" I, II and III with 1, 3 and 3 setae, respectively.Chae totaxy of abdominal tergum V with a1 and p1 (not as in  with 2+2 setae.Furca well developed with 5 setae on each dens.Mucro straight with apex slightly hooked.Tibiotarsi I, II and III with 19, 19 and 18 setae, respec tively, with seta M. Subcoxae "2" I, II and III with 0, 2 and 2 setae, respectively.Even anal valves each with two setae hr.
Antennae shorter than head (about 3/4 length of head).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sensory organ of antennal seg ment III consisting of: two small globular internal sensilla, two subcylindrical guard sensilla (dorsolateral sensillum somewhat shorter than ventrolateral one) and two guard setae between them; ventral microsensillum present.Antennal segment IV with ordinary setae and 6 distinct subcylindrical sensilla; dorsoexternal microsensil lum, subapical organite present; apical vesicle trilobated, ventral side with a few blunt setae (Fig. 53).
Tibiotarsi I, II and III with 19, 19 and 18 setae, respec tively, acuminate distal setae, with seta M present, seta B7 absent on tibiotarsus III.Femora I, II and III with 12, 11 and 10 setae, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 2 and 2 setae, subcoxae "1" I, II and III with 1, 2 and 2 setae, respectively.Claw with inner tooth at 1/3 length of its inner edge, with pair of lat eral teeth (Fig. 56).Empodial appendage absent.Discussion.The new species shares some characters with B. taxcoana Palacios-Vargas & Najt, 1981.Both have the same number of setae on the head, including seta a0, the same number of setae on the dens (5), the same number of setae on tibiotarsi (19, 19 and 18) and the apical vesicle on antennal segment IV is trilobated.They differ in the number of setae hr on the even anal valves (3 in B. taxcoana, 2 in B. saladaensis), in the ratio mucro : dens (1 : 2.12 in B. taxcoana and 1 : 2.6 in the new spe cies), in the size of guard sensilla in the sensory organ of antennal segment III (long sensilla in B. taxcoana, with ventrolateral sensillum somewhat longer than the guard seta and short in the new species, with ventrolateral sen sillum shorter than the guard seta).Denis, 1931 Figs 59-64 Diagnosis.Habitus and buccal cone typical for the genus Brachystomella.Postantennal organ with five vesi cles.7+7 eyes present.Very short ordinary setae, formula of sensory setae s per half tergum: 022/21111.Head without setae a0, sd1 and sd4, setae c3 and c5, one medial seta dx present.Thoracic tergum with 2+2 setae.Furca well developed with 5 setae on each dens.Mucro straight with apex slightly hooked.Tibiotarsi I, II and III with 19, 19 and 18 setae, respectively, with seta M almost in row B. Subcoxae "2" I, II and III with 0, 2 and 2 setae, respec tively.Even anal valves each with two setae hr.
Tibiotarsi I, II and III with 19, 19 and 18 setae, respec tively, with acuminate distal seta; seta M between setae B4 and B5, seta B7 absent on tibiotarsus III.Femora I, II and III with 12, 11 and 10 setae, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 0, 2 and 2 setae, sub coxae "1" I, II and III with 1, 2 and 2 setae, respectively.Claw with inner tooth at 1/3 length of its inner edge, with pair oflateral teeth (Fig. 63).Empodial appendage absent.tomella septemoculata is closest to Brachystomella con torta, described also from Costa Rica.The two species differ in the number of eyes (7+7 in B. septemoculata and 8+8 in B. contorta) and in the shape of the mucro (straight with apex slightly hooked in B. septemoculata and bent in B. contorta).
Antennae shorter than head (about 2/3 length of head).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sensory organ of antennal seg ment III consisting of: two small globular, slightly bent internal sensilla, two subcylindrical guard sensilla (dorso lateral sensillum somewhat shorter than ventrolateral one) and two guard setae between them; ventral microsensillum present.Antennal segment IV with long ordinary setae and 6 indistinct sensilla; dorsoexternal microsensillum, subapical organite present; apical vesicle fairly sim ple, ventral side with a few blunt setae (Fig. 67).

Brachystomella victoriensis
Redescription.Antennae as long as head.Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dorsally, ventral separation well marked.Sensory organ of antennal segment III consisting of: two small globular internal sensilla, two subcylindrical guard sensilla (dorsolateral sensillum somewhat shorter than ventrolateral one) and two guard setae between them; ventral microsensillum present.Antennal segment IV with rather long ordinary setae, with 6 only slightly distinct, long subcylindrical sensilla; dorsoexternal microsensillum present, truncated subapi-cal organite present; apical vesicle trilobated in deep cav ity, ventral side with a few truncated setae (Fig. 72).

Brachystomella villalobosi
Redescription.Antennae shorter than head (about 3/4 length ofhead).Antennal segment I with 7 setae, antennal segment II with 12 setae.Antennae III and IV fused dor sally, ventral separation well marked.Sensory organ of antennal segment III consisting of: two small globular internal sensilla, two subcylindrical guard sensilla (dorso lateral sensillum shorter than ventrolateral one) and two guard seta between them; ventral microsensillum present.Antennal segment IV with rather long ordinary setae, with 6 slightly distinct subcylindrical sensilla; dorsoexternal microsensillum present, truncated subapical organite present; apical vesicle slightly bilobated in deep cavity, ventral side with a few truncated setae (Fig. 79).
Tibiotarsi I, II and III with 19, 19 and 18 setae, respec tively, with acuminate distal setae, seta M (= microchaeta) between setae B4 and B5 present, seta B7 absent on tibiotarsus III.Femora I, II and III with 12, 11 and 10 setae, trochanters I, II and III with 5, 5 and 4 setae, coxae I, II and III with 3, 6 and 7 setae, subcoxae "2" I, II and III with 1, 2 and 2 setae, subcoxae "1" I, II and III with 1, 2 and 2 setae, respectively.Claw with inner tooth at 1/3 length of its inner edge, with pair of lat eral teeth (Fig. 89).Empodial appendage absent.Discussion.The new species shares with B. montebella Najt &Palacios-Vargas, 1986 andB. chilensis Rapoport &Rubio, 1963 the same number of eyes (5+5) and the same number of setae on thoracic tergum I (2+2).It dif fers from the first species in the number of setae on tibio tarsi (18, 18 and 17 in B. montebella and 19, 19, and 18 in the new species), the number of dental setae (6 in B. mon tebella and 5 in the new species) and the shape of the apical vesicle on antennal segment IV (simple in B. mon tebella and trilobated in the new species).The new spe cies is closest to B. chilensis, which has the same number of tibiotarsal setae and the same sensillar formula.The two species differ in the number of dental setae (6 in B. chilensis, 5 in the new species), and vesicles in the postantennal organ (4 in B. chilensis, 5 in the new species), in the shape of apical vesicle (simple in B. chilensis and trilobated in the new species), and in the arrangement of eyes (in B. chilensis D, F and H absent, in the new species F, G and H absent).There are also some differences in chaetotaxy: B. chilensis has seta a0 on head and 3+3 setae on thoracic tergum I, and the new species has no seta a0 on head, and 2+2 setae on thoracic tergum I.
, Muséum national d'Histoire naturelle in Paris, who kindly collected this material for us.
Brachystomella globulosaCassagnau & Rapoport, 1962 possesses short furca like B. villalobosiCassagnau & Rapoport, 1962, B. barrerai Palacios- Vargas & Najt, 1981 and B. minimucronata Palacios- Vargas & Najt, 1981 (with very reduced mucro).All these species have some capitate setae on the body, 2-4 capitate setae on tibiotarsi.B. globulosa has the same number of capitate setae on tibiotarsi I,II and III (3, 4 and  4) like B. barrerai and B. minimucronata (2, 3 and 3 in B.  villalobosi).It differs in the number of setae on each dens (4 in B. globulosa, and 3 in the other species) and in the number of setae hr on the even valves (two in B. globu losa and three in the all other species).
Type material.Lectotype 2 , paralectotype in alcohol pres ently designated, in Natur historiska Riksmuseet (Stockholm, Sweden).Type locality.Falklands Is., Murray Heigths near Port Stan ley, 22.ii.1902,lgt.Svenska Sydpolsexped.Discussion.Brachystomella tuberculata is quite excep tional among the species from the Neotropical region; it differs in the presence of 4+4 setae on thoracic tergum I and the number of setae on subcoxae A " 1" II and III (3-4).It shares the first character with four species from the Australian region: B. ultima Greenslade & Najt, 1987, B. disputa Greenslade & Najt, 1987, B. solidaria Greenslade & Najt, 1987, B. dianae Greenslade & Najt, 1987 and with one species from the South African region: B. coatsi Weiner & Najt, 1991.Four of them (excluding B. ultima) differ from B. tuberculata in the absence of seta a2 on thoracic tergum III (present in B. tuberculata and B. ultima).B. tuberculata and B. ultima differ in the number of vesicles in the postantennal organ (4 in B. tuberculata and 7-8 in B. ultima), in the presence of: setae from m-row of thoracic segments II and III in B. ultima (absent in B. tuberculata), long, bent and slightly capitate setae on tibiotarsi I-III and a pair of lateral teeth on the claw (the last two characters absent in B. ultima).
Brachystomella villalobosi Cassagnau & Rapoport, 1962 is closest to B. barrerai Palacios-Vargas & Najt, 1981.They share the same number of the setae on the dens (3) , the same shape of mucro and of apical vesi cle.They differ in the number of the capitate setae on the tibiotarsus III (2, 3 and 3 in B. villalobosi and 3, 4 and 4 in B. barrerai), in the number of the setae hr on even anal valves (2 in B. villalobosi and 3 in B. barrerai).