Linycus exhortator thoracicus ( Cresson, 1864 )

Dal Pos, Davide, Heilman, Victoria & Welter-Schultes, Francisco, 2022, Platylabini (Hymenoptera: Ichneumonidae: Ichneumoninae) of the south-eastern United States: new distributional data, taxonomic notes, illustrated keys, and an annotated catalogue of the genera and species, Journal of Natural History 56, pp. 1869-1938 : 1893-1895

Linycus exhortator thoracicus ( Cresson, 1864)

( Figures 15 , 16 )

Hoplismenus thoracicus Cresson, 1864: 288 (descr.); Cresson 1916: 59 (cat.).

Platylabus thoracicus Cresson 1877: 201 (distr., key, notes, syn.); Provancher 1879: 37 (descr., key); Provancher 1883: 306 (descr., key); Provancher 1886: 36 (key); Smith 1890: 23 (distr.); Cresson 1887: 191 (cat.); Ashmead 1900b: 567 (distr.); Dalla Torre 1902: 790 (cat.); Cushman 1928: 927 (cat.).

Apaeleticus thoracicus Bradley 1903: 275 (notes).

Platylabus (Apaeleticus) thoracicus Viereck 1917: 343 (key).

Ectopius thoracicus Townes 1944: 316 (cat.); Townes and Townes 1951: 282 (distr., cat.).

Ectopius exhortator thoracicus Heinrich 1956: 651 (descr.).

Linycus exhortator thoracicus Heinrich 1962b: 780 (descr., distr., key); Heinrich 1977: 279 (descr., distr.); Carlson 1979: 542 (cat., distr.); Yu and Horstmann 1997: 675 (cat.); Yu et al. 2016 (cat.).

Original type series

Lecotype ♀ (originally described as ♂ by Cresson (1864), see below) (ANSP). Cresson (1864, p. 288) described Hoplismenus thoracicus from ‘Hab.– Pennsylvania. Mr.Tryon Reakirt [= collected by Mr.Tryon Reakirt]’ reporting it as a male but without specifying the number of specimens included in the description. Cresson (1916, p. 59), in his list of types, reported the lectotype having the ‘Left antenna off’. Townes (1944, p. 316) and Townes and Townes (1951, p. 282) did not specify any number of specimens, but simply reported the information given in the literature. Later on, Heinrich (1962b, p. 780) referred to the specimen as the ‘Holotypus’, highlighting the fact that the actual sex is female and not male. Carlson (1979, p. 317) stated that Cresson (1916, p. 1) ‘indicated which single specimen was to be regarded as the type for each; thus he selected lectotypes for those cases in which he had described a species from more than one specimen’. Hopper (1984, p. 968) reported being unable to see how it can be claimed that Cresson (1916) indicated a single specimen to be the type. This statement contradicted Cresson’s (1916) own statement that ‘In selecting the single type the author has been governed by the present condition of the original material, and has always selected the perfect, or more nearly perfect specimen’ and suggests that Hopper (1984) overlooked this clear indication of Cresson’s (1916) intention of selecting a single name-bearing type (i.e. a lectotype in the modern sense). Cresson’s (1916) lectotype designation was valid and no subsequent lectotype designation has any validity ( ICZN 1999, Article 74.1.1). The fact that the selected specimen eventually could no longer be traced, as suggested by various subsequent authors ( Heinrich 1962b, p. 780; Hopper 1984), could be explained by collection mismanagement and has no influence on the validity of the lectotype selection. Only a careful study of Cresson’s collection can provide more insights. Moreover, the mismatch between the original sex description by Cresson (1916, p. 59) (male) and the observation of a female by Heinrich (1962b, p. 780) is troubling. Hopper (1984, p. 968) experienced a similar situation when, looking at Cresson’s type housed at ANSP and stored in a separate case, he found a mismatch of sexes between the original description and the segregated specimen. Apparently, the two former curators of the collection had personally hand-picked the specimens from the original type series and stored them in a different drawer, and because they both worked on different taxa, they were not skilled in identifying the sex of Ichneumonidae ( Hopper 1984, p. 968) . Therefore, there is a real possibility that the original description contained more than one specimen and that the curators at ANSP selected only one specimen that later was regarded as the ‘holotype’ by Heinrich (1962b, p. 780). Only a careful study of Cresson’s collection can resolve the issue.

Type locality

United States of America, Pennsylvania .

Material examined

UNITED STATES OF AMERICA, MASSACHUSETTS: Cambridge, Middlesex County, 02 October 2010, det . B . Carlson, 2♂♂ (BugGuide); idem, Worcester County, Bolton, 1 September 2010, 2♂♂ ( BugGuide ) ; OHIO: Greene County, Beavercreek, 14 September 2013, det . B . Carlson, 1♂ ( BugGuide ) ; NEW HAMPSHIRE: Grafton Co ., Bedell Bridge S.P., Oliverian Brook, Malaise Trap, 30 September–21 October 1992, leg . D .S . Chandler, 1♀ ( UNHC); Westchester Co ., Armonk, Calder Center, Malaise Trap, 26 July–02 August 1974, leg . C . Calmbacher, 1♂ ( UNHC); idem, 12–18 July 1974 ( UNHC) ; NEW YORK: Albany Co ., nr. Rensselaerville Huyck Preserve, Malaise trap, 17 August 1967, 1♂ ( FSCA) ; TENNESSEE: Sevier Co ., GSMNP Twin Creek R .C., old field, Malaise Trap, 1945 ft, 35.685972°N, 83.500361°W, 20–22 October 2003, leg . Steck, Sutton & Mayor, 2♀♀ ( UCFC); idem, 07– 14 May 2004, 1♂ ( UCFC); Blount Co ., GSMNP Cades Co ., Abrams Crk ., old field – gallery forest edge, 1720 ft, 35.593056°N, 83.842500°W, 09–17 July 2003, leg . Steck, Sutton & Mayor, 1♂ ( UCFC) ; VIRGINIA: Smyth Co ., 09 May 1975, 1♀ ( VMNH) .

Updated distribution ( Figure 16 )

CANADA: Ontario ( Heinrich 1962b); UNITED STATES OF AMERICA: Georgia ( Heinrich 1977), Indiana ( Heinrich 1962b), Maine ( Heinrich 1962b), Massachusetts ( Carlson 2010a), Michigan ( Heinrich 1962b), Missouri ( Heinrich 1962b), New Hampshire ( Cresson 1877), New Jersey ( Smith 1890), New York ( Cresson 1877), Ohio ( Carlson 2011), Pennsylvania ( Cresson 1864, 1877), Rhode Island ( Townes and Townes 1951); Tennessee ( Heinrich 1977), Virginia (new state record).

Host

Although host records for the subspecies thoracicus are unknown, the nominate subspecies (Europe) is a parasitoid of Geomemetridae ( Lepidoptera ) ( Shaw et al. 2015).

Male

The first description of a male was provided by Heinrich (1956, p. 651). However, Heinrich (1956, p. 651) did not realise the problem with the sex of the syntypes (see above, Type series), and believed he had described the female for the first time.

Comments

The species Linycus exhortator (Fabricius, 1787) is represented by three subspecies, one with a European distribution (the nominotypical subspecies), and the other two occurring in the Nearctic ( Heinrich 1962b, p. 780). Of these two, only one occurs in the south-eastern United States, L. exhortator thoracicus . Unfortunately, there are some issues regarding the state distribution of this latter subspecies within the US. Townes and Townes (1951, p. 282) reported only three states for the distribution of the subspecies, namely New York, Pennsylvania and Rhode Island. Yu et al. (2016) did not report Rhode Island in their catalogue. Another issue revolves around Carlson (1979, p. 542). In his catalogue, the author mentioned the species as occurring from ‘ Maine s. to Va., w. to Wis. And Mo’. This distribution probably stems from the idea already advanced by Heinrich (1977, p. 279) that the taxon is probably widespread throughout the eastern part of the country, ‘From Michigan and Ontario south to Georgia and Tennessee’. However, these statements are too vague and inconsistent, and it is not clear whether they are substantiated by any specimens. Therefore, we are not considering Heinrich’s (1977) and Carlson’s (1979) vague statements to represent valid distributional records – even though they are very probably true. The records from Massachusetts and Ohio are from BugGuide and identified by Carlson (2010a, 2013) as Linycus exhortator .

Figures

Figure 15. Linycus exhortaor thoracicus (Cresson, 1864), ♀. a) Habitus, dorsal view. b) Habitus, lateral view. c) Head, frontal view. d) Propodeum and metasoma, dorsal view.

Figure 16. Linycus exhortaor thoracicus (Cresson, 1864), distributional map: known records (in blue) and newly recorded state (in yellow).