Bactericera nigrilla (Crawford, 1911) Halbert & Burckhardt, 2020

Halbert, Susan E. & Burckhardt, Daniel, 2020, The psyllids (Hemiptera: Psylloidea) of Florida: newly established and rarely collected taxa and checklist, Insecta Mundi 2020 (788), pp. 1-88 : 55-61

Bactericera nigrilla (Crawford, 1911) , new combination, revived status

( Fig. 151–157 , 162–180 )

Trioza salicis Mally 1894: 161 ; junior secondary homonym of Chermes salicis Linnaeus 1761: 264 , in Trioza .

Trioza nigra Crawford 1910a: 232 ; junior primary homonym of Trioza nigra Kuwayama 1910: 57 ; synonymized with Trioza salicis Mally by Crawford 1914: 91.

Trioza nigrilla Crawford 1911b: 503 ; replacement name for Trioza nigra Crawford nec Kuwayama .

Trioza louisianae Aulmann 1912: 144 ; replacement name for Trioza nigra Crawford nec Kuwayama .

Trioza minuta similis Crawford 1911a: 425 , 433; unavailable name ( ICZN 1999 /2012: Article 45.6.4), deemed to be infrasubspecific; synonymized with Trioza salicis Mally by Crawford 1914: 91. Phylloplecta salicis ; Caldwell 1938a: 250.

Phylloplecta multidubiata Caldwell 1939: 211 ; replacement name for Trioza salicis Mally nec Chermes salicis Linnaeus (in Phylloplecta ).

Materials examined. Type material of Trioza salicis Mally. USA: syntypes 6 adults, Iowa, Ames ( USNM, dry mounted).

Type material of Trioza nigra Crawford. Lectotype ♂: USA: “Colo”, “ Coll. CF Baker ” ( USNM, dry mounted), here designated; paralectotypes 4 ♂ same as lectotype; paralectotypes 2 ♀, Louisiana (G.R. Pilate) ( USNM, dry mounted); paralectotypes 2 ♂, Illinois, Algonquin ( Nason ) ( USNM, dry mounted).

Type material of Trioza minuta similis Crawford. Lectotype ♂: USA: “Oreg. 2506”, “Coll CF Baker”, “ Trioza minuta similis Crawf. ” ( USNM, dry mounted), here designated; paralectotypes 5 ♂, 6 ♀, 1 pin without specimen, same data as lectotype.

Additional material. USA: Florida: Specimens from Alachua and Collier counties.

Description. Adult ( Fig. 151, 152 ). Coloration ( Fig. 151 ). Head jet-black. Clypeus dark brown. Antennal segments 1–3 whitish, segments 4–10 dark brown or black. Thorax dark orange with dorsum mostly dark brown to black. Legs yellowish; pro- and mesotibiae dark brown posteriorly; apical segments of pro- and mesotarsi brown. Forewings with colorless, transparent membrane; veins whitish in basal three quarters and ochreous apically, vein A 1 of the same color as other veins. Hindwings with colorless, transparent membrane. Abdomen yellow to orange with mostly black tergites; intersegmental membrane orange. Male and female proctiger with black patches; paramere dark brown. – Structure. Head inclined in a 45° angle from longitudinal body axis ( Fig. 151 ), narrower than mesonotum in dorsal view. Vertex ( Fig. 153 ) subtrapezoidal, about twice as wide as long along mid line; disk with some scattered short hairs, mostly smooth except for margins which bear a tubercular microsulpture; genal processes about as long as vertex along mid-line, conical, subacute apically. Antenna 1.8–1.9 times as long as head width, with a single subapical rhinarium ( Fig. 154 ) on each of segments 4, 6, 8 and 9; segments 3, 9 and 10 slightly thicker than 4–8; relative length of flagellar segments as 1.00: 0.5: 0.5: 0.4: 0.5: 0.4: 0.2: 0.1; relative length of antennal segment 10 and terminal setae as 1.0: 0.9: 0.5 ( Fig. 155 ). Rostrum 0.5 times as long as head width. Forewing ( Fig. 156 ) 5.2–5.5 times as long as head width, 2.8 times as long as wide, lanceolate, widest in the middle, apex subacute, lying in cell m 1; vein Rs weakly sinuous; bifurcation of vein M distal to line connecting apices of veins Rs and Cu 1a; surface spinules ( Fig. 157 ) present in distal half of wing, sometimes faint, irregularly spaced, leaving spinule-free stripes along the veins. Male terminalia ( Fig. 164–171 ) with proctiger 0.3 times as long as head width, posterior lobes short, triangular. Male subgenital plate short, with very few setae. Paramere longer than proctiger; digitiform, in profile, relatively straight; inner face beset with moderately long setae, apex acute. Distal segment of aedeagus slightly longer than proctiger; apical inflation slightly longer than a third of the segment; sclerotized end tube of ductus ejaculatorius short and sinuate. Female terminalia ( Fig. 162–163 ) with proctiger 0.6 times as long as head width, sparsely covered with a few moderately long setae; dorsal margin of proctiger distal to circumanal ring, in lateral view, almost straight in the middle, curved down apically; apex, in profile rounded, with a very small hook. Circumanal ring oval, 0.4 times as long as proctiger; consisting of two unequal rows of pores. Subgenital plate 0.6 times as long as proctiger, truncate apically with a small median lobe. Dorsal valvulae triangular, ventral valvulae almost straight; lacking teeth. – Measurements (in mm; 1 ♂, 1 ♀). Head width 0.52; antenna length 0.94–1.00; forewing length 2.68–2.86; length of male proctiger 0.16; paramere length 0.20; length of distal segment of aedeagus 0.18; length of female proctiger 0.32.

Fifth instar immature ( Fig. 172–174 ). Coloration. In life, dirty yellowish, weakly sclerotized, semitransparent. Tips of antennae and rostrum dark. Abdomen light green; yellow in the middle because of the translucent bacteriome. – Structure. Body strongly dorso-ventrally flattened, oval, 1.5 times as long as wide; dorsally flat. Dorsal sclerites covered in granular microsculpture and sparse microscopical setae, lacking sectasetae. Marginal sectasetae truncate present in following numbers (one side only): head ( Fig. 175 ) 31–37; forewing pad ( Fig. 176 ) 72–85; hindwing pad ( Fig. 177 ) 14–15; caudal plate ( Fig. 178 ) 71–81. Each half of head broadly rounded anteriorly. Antenna 0.3 times as long as forewing pad; inserted on ventral body side, three-segmented, segment 3 with four rhinaria. Humeral lobe reaching well beyond anterior eye margin, narrowly rounded. Tarsal arolium ( Fig. 180 ) lobe-like, oval, with short unguitractor, lacking petiole, slightly longer than claws which are both well developed. Outer circumanal ring ( Fig. 179 ) small, transversely oval; on ventral body side; distance from hind margin to hind margin of caudal plate 4.0 times as long as distance from fore to hind margin of outer circumanal ring (measured in the middle); consisting of a single row of oval pores. – Measurements (in mm; 4 immatures). Body length 1.90–2.12; antenna length 0.28–0.30.

Distribution. Reported from USA: IA ( Mally 1894, as Trioza salicis ), CO, LA, IL ( Crawford 1910b, as Trioza nigra ), OR ( Crawford 1911a, as Trioza minuta similis ). – Florida: Alachua, Collier, Hillsborough, Marion , Miami- Dade, Polk, St. Lucie counties. This species was discovered in Florida in suction trap samples. The first specimen was collected in the Miami-Dade County trap (FSCA# E2007-8729). In 2010 (FSCA# E2010-4570), a specimen was collected in a Collier County suction trap. The psyllid has become much more common in the Collier County traps than in Miami-Dade County. A single specimen was collected in a Polk County trap in 2012 (FSCA# E2012- 1758). Suspecting that this psyllid was on willows, we surveyed by sweeping willows near the Immokalee (Collier County) suction trap. Several adults were found by sweeping willows in both Collier (FSCA# E2013-6535, E2014- 2837, 2840) and Hillsborough (FSCA# E2016-1490) counties. The first immatures were found on willows ( Salix caroliniana Michx. , Salicaceae ) in Alachua Co. on 3.iii.2017 (FSCA# E2017-1199, 1552). This is a new record for Florida, reported here.

Host plant. Salix caroliniana Michx. (Salicaceae) ; probably also other Salix spp.

Comments. Salix is a predominantly Holarctic genus which was at least twice successfully colonized by psyllids, viz. by species of Cacopsylla and of Bactericera . In Salix and both psyllid genera the identification of species is difficult for the non-specialist as often interspecific differences are small and intraspecific variation is pronounced. The Nearctic Cacopsylla species associated with Salix spp. have been studied in detail (e.g. Jensen 1951; Hodkinson 1978) but not those of Bactericera . In the series of papers “American Psyllidae ”, Crawford (1910a, 1910b, 1911a, 1911b) erected eleven new species and forms of Trioza associated with Salix . Most of his descriptions and illustrations are not diagnostic. In the monograph on the psyllids of the New World, Crawford (1914) synonymized several of his taxa recognizing five species of Salix inhabiting triozids: Ceropsylla californica (Crawford) , Trioza arizonae Aulmann, T . maura Foerster (with five synonyms), T. salicis Mally (with five synonyms and three replacement names) and T. varians Crawford. Caldwell (1938a) and Tuthill (1943) followed mostly Crawford (1914) but noted the name T. salicis Mally cannot be used for reasons of homonymy. Caldwell (1939) introduced the replacement name Phylloplecta multidubiata , an unnecessary action as there were available names for this taxon among the synonyms of T. salicis Mally. Tuthill (1943) chose the oldest synonym, T. minuta , as valid name and included T. arizonae as a variety of the former. He also moved T. californica from Ceropsylla back to Trioza . Tuthill’s (1943) species concepts were adopted in the catalogues of Hodkinson (1988) and Burckhardt and Lauterer (1997b). The last two authors redefined Bactericera and included all previous Trioza species that developed on Salix . They pointed out that B. minuta of Crawford (1914), Caldwell (1938a) and Tuthill (1943) was a species complex.

The specimens from Florida fit the broad concept of Bactericera minuta by the North American authors. We have examined the relevant types (USNM) of the species currently listed as synonyms of B. minuta : i.e. Trioza assimilis Crawford, T . marginata Crawford, T . minima Crawford, T. minima similis Crawford, T . nigra Crawford and T. salicis Mally. We conclude that the types of the six nominal taxa represent three species but there are additional undescribed species in the USNM misidentified as Trioza minuta by J.S. Caldwell and L.D. Tuthill. Hence, all published records of Bactericera (or Trioza ) minuta are doubtful. The three species we recognize here should be named Bactericera flori , B. minuta and B. nigrilla . The synonymies of the first two are detailed in Appendix 1. Here we discuss the ones of B. nigrilla .

Trioza salicis Mally nec Linnaeus, Trioza nigra Crawford nec Kuwayama and Trioza minuta similis Crawford represent the same species, confirming, in part, Crawford’s (1914) synonymies. It differs from related species as indicated in the key in Appendix 1. It should be called Bactericera nigrilla Crawford for the following reasons.

Trioza salicis Mally, 1894 , constitutes a junior secondary homonym of Chermes salicis Linnaeus, 1761 (in Trioza ). According to Löw (1882), Chermes salicis Linnaeus is congeneric with five European Trioza species developing on Salix ( Trioza albiventris Foerster, 1848 , T. curvatinervis Foerster, 1848, T. maura Foerster, 1848 , T. salicivora Reuter, 1876 , and T. striola Flor, 1861). All these species are now referable to Bactericera ( Burckhardt and Lauterer 1997b) . As the description of Linnaeus (1761) is not diagnostic, Löw (1882) considered T. salicis Linnaeus a nomen dubium. Junior secondary homonyms are available as species names when the homonymy is removed by transfer to another genus. As Trioza salicis Mally and Chermes salicis Linnaeus are congeneric, independent if in Trioza or in Bactericera , and despite the fact that the latter is a nomen dubium, Trioza salicis Mally cannot be used as valid species name. The next oldest is Trioza nigra Crawford, 1910 , a junior primary homonym of Trioza nigra Kuwayama, 1910 , with the replacement names Trioza nigrilla Crawford, 1911 , and Trioza louisianae Aulmann, 1912 . The former is older and has priority and should, therefore, be used for the species under discussion as Bactericera nigrilla (Crawford, 1911) , new combination and revived status. Another synonym, Trioza minuta similis Crawford, 1911 , is deemed to be infra-subspecific and, therefore, invalid ( ICZN 1999 /2012: Article 45.6.4). Crawford (1911a) used the name “ similis ” for three taxa: the species Trioza similis Crawford, 1910 (a junior subjective synonym of Trioza albifrons Crawford, 1910 ), and the two forms Trioza fulvida similis Crawford, 1911 , and Trioza minuta similis Crawford, 1911 . Later, Crawford (1914) referred to the last taxon as Trioza minuta var. similis , indicating that he considered these forms as varieties rather than subspecies. Caldwell (1939), finally, proposed the replacement name Phylloplecta multidubiata for Trioza salicis Mally nec Linnaeus, which we consider a junior objective synonym of Bactericera nigrilla .

Bactericera nigrilla is characterized by the following combination of characters: long genal processes; black head; antennal color; lanceolate forewings bearing surface spinules; relatively short posterior lobes on the male proctiger; digitiform, apically pointed parameres; relatively short apical dilatation of the aedeagus with the moderately long sclerotized end tube of the ductus ejaculatorius; short female terminalia; apically truncate female proctiger and subgenital plate. There is some variation in the shape of the posterior lobes of the male proctiger ( Fig. 162, 163 ) and the distal segment of the aedeagus ( Fig. 166–169 ). These differences are mostly due to the state of preservation of the specimens, the types being older than a century, to a lesser degree also to individual variation. The genal processes of the types of Trioza minuta similis appear slightly shorter. The types appear to represent young specimens lacking the very dark color, which may also explain the shorter genal processes. More material, including long series from all over North America, will be necessary to test our conclusions.

Figures

Figures 151–157. Bactericera nigrilla. 151) Mature adult. 152) Teneral adult and skin. 153) Head, dorsal view. 154) Rhinarium on antennal segment 4. 155) Antennal segments 9 and 10. 156) Forewing. 157) Surface spinules. Scales: 153) 0.1 mm; 154, 155) 0.03 mm; 156) 0.5 mm; 157) 0.1 mm. (Photos by Lyle Buss, University of Florida, Entomology Department: 151, 152).

Figures 158–171. Terminalia of Batericera spp. from Salix. 158–161) Bactericera minuta. 158) Male terminalia, in profile. 159) Inner face of paramere, in profile. 160) Distal segment of aedeagus; with the same locality data as lectotype of Trioza minuta Crawford. 161) Distal segment of aedeagus; lectotype of Trioza marginata Crawford. 162–171) Bactericera nigrilla. 162) Female terminalia, in profile. 163) Female subgenital plate, in ventral view. 164) Male terminalia, in profile; specimen from Florida.165) Male terminalia, in profile; lectotype of Trioza nigra Crawford. 166) Inner face of paramere, in profile; specimen from Florida. 167) Inner face of paramere, in profile; lectotype of Triozanigra Crawford. 168) Distal segment of aedeagus; specimen from Florida.169) Distal segment of aedeagus; syntype of Trioza salicis Mally. 170) Distal segment of aedeagus; lectotype of Trioza nigra Crawford. 171) Distal segment of aedeagus; lectotype of Trioza minuta similis Crawford. Scales: 158, 164, 165) 0.1 mm; 159–161) 0.05 mm; 162, 163) 0.1 mm; 166–171) 0.05 mm.

Figures 172–180. Bactericera nigrilla, last instar. 172) Habitus. 173) Habitus, probably parasitized. 174) Habitus, cleared specimen. 175) Marginal sectasetae of head. 176) Marginal sectasetae of forewing pad. 177) Marginal sectasetae of hindwing pad. 178) Marginal sectasetae of caudal plate. 179) Circumanal rings. 180) Tarsal apex. Scales:74) 0.4 mm; 175–178) 0.04 mm; 179) 0.04 mm; 180) 0.02 mm. (Photos by Lyle Buss, University of Florida, Entomology Department: 172, 173).