The Cryptic Song Species of Chrysoperla
Charles S. Henry, Dept of Ecology & Evolutionary Biology, University of Connecticut
Below are the known song species of the carnea group of Chrysoperla, which are morphologically very similar to one another. Beneath each species name is an oscillograph and sonograph of the typical song of the species, recorded at 25 degrees C. The time axes are seconds, and the vertical axis of the sonograph (the lower of the two graphics) is in Hertz (NOT kilohertz, as in more familiar insect songs!). Click on the large-print, highlighted species name or any part of either graphic, and you can hear what these songs "sound" like (although you would have to put your ear almost on top of the singing insect, in order to perceive anything remotely like this in the field or laboratory). These substrate-borne signals are of very low frequency, so do not expect to hear much unless you use headphones, or have a subwoofer hooked up to your computer. Included are, arranged by geographical region:
From Europe and western Asia, seven song species: C. mediterranea, C. lucasina, C. carnea (formerly called Cc4 "motorboat"), C. pallida (formerly Cc2 "slow-motorboat"), C. agilis (Cc3 "maltese"), C. zastrowi sillemi (Cc5 "generator"), and C. heidarii (CcX-Asia).
From west/central Asia, at least three song species, so far lacking complete descriptions of their songs and morphology:
(1) "C. adamsi-Kygyzstan," collected in Kygyzstan and so named for its song which is highly convergent on that of C. adamsi from North America;
(2) "C. downesi-Kygyzstan," collected in Kygyzstan and so named for superficial similarity of its song to that of C. downesi from North America;
(3) "C. motorboat-Kygyzstan," collected in Kygyzstan and so named for apparent similarity of its call to that of European C. carnea.
From eastern Asia, at least two song species: C. nipponensis (formerly called "C. downesi-China" or C. nipponensis Type A), and C. nigrocapitata (formerly called C. nipponensis Type B).
From Africa, one song species (so far): C. zastrowi zastrowi -- the only member of the carnea group known to be present south of the equator.
From North America, six song species: C. plorabunda, C. adamsi, C. johnsoni, C. downesi s. str., and C. calocedrii, plus an undescribed variant of C. downesi known informally as C. "downesi-2." Interestingly, the European species C. agilis strays into North America as a stable population in north-central Alaska, while C. zastrowi sillemi has become established in the desert southwest of North America.
From Central America, one song species: the wide-ranging Asian/European/African/North American subspecies C. zastrowi sillemi., reported for the first time from Guatemala.
With practice, you will be able to identify living individuals of the carnea-group to song species simply by watching the rhythm with which the insect is vibrating its abdomen and comparing that to the recorded signals below.
Another species group within the genus Chrysoperla is the pudica group. These species possess a type of male internal genitalia that distinguishes them from members of the carnea group. The species of the pudica group also tremulate, producing substrate-borne courthship and mating songs. Less is known about these songs, in part because the songs do not seem to play such a vital role in communication between the sexes as in the carnea group, and are therefore more difficult to observe and record.
From North America, three species are commonly found: C. rufilabris, C. harrisii, and C. comanche.
EUROPEAN and ASIAN SONG SPECIES:
Chrysoperla mediterranea (Hölzel) This typically dark-green, conifer-associated species ranges across southern to central Europe and across the north African Mediterranean coast. Unlike most other members of the carnea species-group, C. mediterranea retains its dark green coloration during winter diapause. Shown below is one "shortest repeated unit" or SRU, the unit of exchange by partners during a courtship and mating duet. In this case, the SRU consists of many short, closely-spaced volleys of abdominal vibration.
For more information, see Henry, C. S., S. J. Brooks, P. Duelli, and J. B. Johnson. 1999. Revised concept of Chrysoperla mediterranea (Hölzel), a green lacewing associated with conifers: Courtship songs across 2800 kilometers of Europe (Neuroptera: Chrysopidae). Syst. Entomol. 24(4): 335-350.
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Chrysoperla lucasina (Lacroix) This often abundant species ranges across most of temperate Europe and eastward into western Asia, as well as across the northern quarter (at least) of Africa. Like C. mediterranea it stays green during winter diapause. Shown below is just the initial portion of one SRU of the male or female solo "calling song," consisting of numerous, fairly long volleys of abdominal vibration. The dueting song is similar but consists of just 4 or 5 volleys, exchanged frenetically with the partner in what looks like one continuous string of volleys.
For more information, see Henry, C. S., S. J. Brooks, J. B. Johnson, and P. Duelli. 1996. Chrysoperla lucasina (Lacroix): a distinct species of green lacewing, confirmed by acoustical analysis (Neuroptera: Chrysopidae). Syst. Entomol. 21: 205-218.
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C. pallida Henry, Brooks, Duelli & Johnson (formerly Cc2 slow-motorboat) The range of this species covers most parts of temperate western Europe, notably Switzerland and northern Italy westward across most of France at least to central Spain, northward into the British Isles, eastward to Hungary, and southeastward into Greece. It is usually found in shrubs and trees at the edges of fields, or even in open woodlands. Shown below is one SRU of the length typical of solo songs, consisting of many short volleys. Songs exchanged during duets tend to be shorter -- 8-16 volleys -- but are otherwise very similar to the song illustrated. The 'spiky' appearance in the oscillograph is due to the insect actually striking the substrate with its abdomen at the start and/or end of each volley.
For more information, see Henry, C. S., S. J. Brooks, P. Duelli, and J. B. Johnson. 2002. Discovering the true Chrysoperla carnea (Stephens) (Insecta: Neuroptera: Chrysopidae) using song analysis, morphology, and ecology. Ann. Entomol. Soc. Am. 95(2): 172-191.
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C. agilis Henry, Brooks, Duelli & Johnson (formerly Cc3 Maltese) The range of this lively species is similar to that of Chrysoperla mediterranea, i.e., mostly southern Europe, but also found on the Azores archipelago the middle of the Atlantic Ocean. Until recently its eastern limit was thought to be Iran, near Tehran. However, in the winter of 2007 irrefutable specimens of this song species were collected in Fairbanks, Alaska, thousands of kilometers from the closest known population! It was originally nicknamed "Maltese" because first collections of this species came from the island of Malta. Shown below are three SRUs, each consisting of a single long volley of abdominal vibration, which an insect typically produces repetitively. In a duet, the partner would insert his or her SRU between the SRUs illustrated. As in Cc2, spikes result from the abdomen striking the substrate.
A complete description of
the species is given in Henry CS, Brooks SJ, Duelli P, Johnson JB.
2003. A lacewing with the wanderlust: the European song species
'Maltese', Chrysoperla agilis sp.n., of the carnea group of Chrysoperla (Neuroptera: Chrysopidae). Systematic Entomology 28: 131-48.
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C. carnea (Stephens) (formerly Cc4 motorboat) A very wide-ranging species, found across most of Eurasia from northern Italy north to Finland, Norway, and northern Scotland and eastward to central Russia. Apparently absent from extreme western Europe, e.g., Spain. It is also rare or absent from the warmest parts of southern Europe and is extremely uncommon south of the Po valley in northern Italy. Shown below are two SRUs, each consisting of many short, closely-spaced volleys of abdominal vibration. Once entering a duet, an individual lengthens its SRU significantly, often to several minutes! Nicknamed for the burbling or throbbing acoustic effect of the closely-spaced volleys.
The well-known but vaguely diagnosed species C. carnea (Stephens, 1835) has been shown to correspend to the Cc4 song species, based on geographic distribution, ecology, ecophysiology and adult morphology. The arguments for this designation are given in Henry, C. S., S. J. Brooks, P. Duelli, and J. B. Johnson. 2002. Discovering the true Chrysoperla carnea (Stephens) (Insecta: Neuroptera: Chrysopidae) using song analysis, morphology, and ecology. Ann. Entomol. Soc. Am. 95(2): 172-191.
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C. zastrowi sillemi (Esben-Petersen) (formerly Cc5 generator) A widespread "nomadic" species in the Near and Middle East,
from Israel in the west to Oman and beyond (see below) in the east, often but not always associated
with a warm, dry climate. As the name indicates, Cc5 from the Arabian peninsula is now considered a subspecies of C. zastrowi
(Esben-P) from southern Africa (see next entry). However, the
taxonomic status of this subspecies was soon rendered uncertain. In 2006-7, lacewings collected in southern India were found to sing the C. z. arabica song and to strongly resemble the latter in subtle morphological ways. That finding suggests a range extension for C. z. arabica,
east from Oman deep into the Indian subcontinent, where the climate is
quite different. However, the name given to "carnea-like" lacewings in India is Chrysoperla sillemi (Esben-Petersen), preserved specimens of which seem morphologically indistinguishable from C. z. arabica. Such evidence was used to make C. z. arabica a junior synonym of C. z. sillemi
(Esben-Petersen) in 2010 (documented in Henry, C. S., Brooks, S. J.,
Johnson, J. B., Venkatesan, T., & Duelli, P. (2010). The most
important lacewing species in Indian agricultural crops, Chrysoperla sillemi (Esben-Petersen), is a subspecies of Chrysoperla zastrowi (Esben-Petersen) (Neuroptera: Chrysopidae). Journal of Natural History 44, 2543-2555.
Shown below are six SRUs, each consisting of a single long volley of abdominal vibration, which an insect typically produces repetitively. In a duet, the partner would insert his or her SRU between the SRUs illustrated, resulting in a slower tempo of volley repetition. Originally nicknamed for the tone-generator purity of its acoustical signal.
A complete description of
this subspecies is found in Henry CS, Brooks SJ, Duelli P, Johnson
JB. 2006. Courtship song of the South African lacewing Chrysoperla zastrowi (Esben-Petersen)
(Neuroptera: Chrysopidae): evidence for a trans-equatorial geographic
range? Journal of Natural History 40: 2173-95.
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Chrysoperla zastrowi (Esben-Petersen) This is (apparently) the only member of the carnea group that occurs south of the equator. It has been considered to be an Afro-tropical species, ranging broadly across the African continent from Sudan in the north to the southernmost Cape. It has also been collected from Ascension Island, in the northern South Atlantic Ocean. However, recent evidence (see previous entry) suggests that C. zastrowi includes at least two song variants, which are now recognized as subspecies. C. zastrowi zastrowi is the nominate form from southern Africa discussed here; a second subspecies is C. zastrowi sillemi, described above. Shown below are four SRUs of South African C. zastrowi, each consisting of a single very long volley of abdominal vibration, which an insect typically produces repetitively. In a duet, the partner inserts his or her SRU between the SRUs illustrated, resulting in a slower tempo of volley repetition -- exactly as seen in C. z. sillemi In fact, except for the greater length of each volley and greater spacing between the volleys, the song of C. z. zastrowi is very similar to that of C. z. sillemi It is expected that songs of intermediate phenotype will be found in the vast region between South Africa and the Arabian Peninsula.
A publication describing C. zastrowi is listed under the section above about C. zastrowi sillemi (Cc5 generator).
Chrysoperla plorabunda (Fitch) A widespread species, found from east coast to west coast and from central Canada into northern Mexico. Shown below are fourteen SRUs, each consisting of a single volley of abdominal vibration, which an insect typically produces repetitively. In a duet, the partner would insert his or her SRU between the SRUs illustrated; the partners match their tempo to one another.
This is the species in which vibrational communication was first demonstrated -- i.e., see Henry, C. S. 1979, Acoustical communication during courtship and mating in the green lacewing Chrysopa carnea (Neuroptera: Chrysopidae). Ann. Entomol. Soc. Am. 72: 68-79 (back then, plorabunda was thought to be part of C. carnea Stephens, and the name Chrysoperla was not commonly used).
For more up-to-date information, see Henry, C. S., M. M. Wells, and R. J. Pupedis. 1993. Hidden taxonomic diversity within Chrysoperla plorabunda (Neuroptera: Chrysopidae): two new species based on courtship songs. Ann. Entomol. Soc. Am. 86(1): 1-13.
A study of the extraordinary dueting capabilities in the species can be found in Henry CS, Wells MLM. 2006. Testing the ability of males and females to respond to altered songs in the dueting green lacewing, Chrysoperla plorabunda (Neuroptera: Chrysopidae). Behavioral Ecology and Sociobiology 61: 39-51.
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Chrysoperla adamsi Henry, Wells, & Pupedis A song species from western North America, ranging (at least) from the Pacific Northwest to southern California. Shown below are five SRUs, each consisting of a single longish volley of abdominal vibration followed by an unstructured "rumble." A sexually receptive individual typically produces a series of such SRUs. In a duet, the partner would insert his or her SRU between the SRUs illustrated. As in C. plorabunda, the partners match their tempo to one another. Note the similarity in frequency structure to the song of C. plorabunda: molecular data indicate that the two are probably sister species.
See Henry, C. S., M. M. Wells, and R. J. Pupedis. 1993. Hidden taxonomic diversity within Chrysoperla plorabunda (Neuroptera: Chrysopidae): two new species based on courtship songs. Ann. Entomol. Soc. Am. 86(1): 1-13.
The molecular work is summarized in Henry, C. S., M. L. M. Wells, and C. M. Simon. 1999. Convergent evolution of courtship songs among cryptic species of the carnea-group of green lacewings (Neuroptera: Chrysopidae: Chrysoperla). Evolution 53(4): 1165-1179.
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Chrysoperla johnsoni Henry, Wells, & Pupedis A song species from western North America, ranging (at least) from the Pacific Northwest to southern California and SW Arizona. Shown below is one SRU. In this species, the SRU is multisyllabic, consisting of 2-5 volleys of abdominal vibration; the last volley of the song is terminated by an unstructured "rumble." In a duet, the partners exchange these multisyllabic SRUs politely. Songs of individuals from the southern part of the range exhibit longer volleys/duets than those of northern individuals, and the variation is clearly clinal in pattern. Chrysoperla johnsoni forms a monophyletic clade with C. plorabunda and C. adamsi (see Henry et al. 1999 reference, given above)
For additional information, see Henry, C. S. 1993. Chrysoperla johnsoni Henry (Neuroptera: Chrysopidae): acoustic evidence for full species status. Ann. Entomol. Soc. Am. 86(1): 14-25.
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Chrysoperla downesi (Smith) [s. str.] This song species is the North American analogue of C. mediterranea in Europe. Like mediterranea, it is strongly associated with conifers, and it is characterized by conifer-matching dark-green coloration. Its range is northeastern North America from Connecticut northward into Canada and Alaska. Western variants of this song species occur in the Pacific Northwest south to Mexico, and probably comprise several additional, distinct song species, e.g., "C. mohave" in the American southwest. Shown is one SRU; the species is unusual in producing two different types of volleys in each song.
For more information, see Henry, C. S. 1980. The courtship call of Chrysopa downesi Banks [sic] (Neuroptera: Chrysopidae): its evolutionary significance. Psyche 86: 291-297.
The C. mohave biotype is described in Henry, C. S. 1993. Chrysoperla mohave (Banks) (Neuroptera: Chrysopidae): two familiar species in an unexpected disguise. Psyche 99(4): 291-308.
A study of possible
adaptive features of lacewing songs to the properties of their distinct
substrates is described in Henry CS, Wells MLM. 2004. Adaptation or
random change? The evolutionary response of songs to substrate
properties in lacewings (Neuroptera: Chrysopidae: Chrysoperla). Animal
Behaviour 68: 879-95.
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THE PUDICA SPECIES GROUP OF CHRYOSPERLA: NORTH AMERICAN REPRESENTATIVES:
Chrysoperla comanche (Banks): This species is common in the U.S. southwestern states, including New Mexico, Arizona, and southern California. Typically, the markings on the genae (face) of this insect are red, the wing apices are pointed, and the crossveins in the wings are mostly green [rather than brown or black as in C. rufilabris (Burmeister), its closest relative]. The song of C. comanche is quite dramatic. It starts at very low intensity as a series of rhythmic abdominal movements, then increases progressively in amplitude to a crescendo toward the end. It can be likened best to a 'purr'. Both males and females produce the same type of song, which they exchange politely in a duet -- just as in the cryptic song species of the carnea group. The song (SRU), shown below, appears to be one prolonged volley of abdominal vibration, which can last for over half a minute -- although close inspection of its structure reveals that it may actually consist of a series of very short, very closely spaced volleys, each made up of 3 or 4 abdominal cycles. Its spectral (frequency) characteristics are complex, involving a fundamental carrier frequency accompanied by several harmonics.
For more information, see Henry, C. S. 1989. The unique purring song of Chrysoperla comanche (Neuroptera: Chrysopidae), a western sibling of C. rufilabris. Proc. Entomol. Soc. Wash. 91(2): 133-142.
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