Amblycorypha rivograndis: Tettigoniidae » Phaneropterinae » Amblycorypha uhleri Group
Introduction
Identification: The two species candidates in my location with this specific song type are Amblycorypha uhleri and Amblycorypha rivograndis. A distinction can be made based on length of the tegmina (Walker, 2004); however, mine measured exactly between the ranges of the two species. Therefore, I asked
Wil Hershberger to analyse the song of mine as well as the song of another male recorded during the same time period in the same location. For both, Wil Hershberger was able to match the song to that of A. rivograndis based on the relative simplicity of the ending flourish (personal communication, January 2023).
The Amblycorypha uhleri Group: Diagnostic features include deep humeral sinus of lateral lobe of pronotum, each metanobal lobe longer than wide, males with 4 dark marks on outer edges of pronotal disk, ovipositors no longer than 10 mm, maximum length of tegmen 31 mm and of pronotum, 6.6 mm. (Walker, 2004).
Amblycorypha rivograndis pronotum showing the diagnostic 4 dark marks:
Specific epithet:
Amblycorypha rivograndis (Walker 2005)
Walker (2004) notes that "This species is named for its type locality near the Rio Grande River (rivo, stream; grandis, great)."
Amblycorypha rivograndis are a small, cute species of the Amblycorypha uhleri Group. As with my Amblycorypha huasteca, I had no intention of raising these guys, but happened to find eight adults that I then cared for. I overwintered their eggs and raised an F1 generation. This forum addition is based on my personal experience in raising this delightful species.
Amblycorypha rivograndis:
This short discussion contains the following sections: 1) Housing and Care, 2) Life Cycle and F2 Update, 3) Song, 4) Mating, Spermatophylax, Laying Eggs, 5) Observations, and 6) A Few Resources.
Housing and Care of Amblycorypha rivograndis
HOUSING
After collecting a small handful of adult A. rivograndis from atop tall grasses, I cared for the adults and provided a habitat for thriving and breeding.
For housing, I use large butterfly cages that measure 36" x 24" x 24". I add a variety of native plants for the katydids to munch on and perch on. My Amblycorypha rivograndis spend most of their time on plant leaves.
Sample cages for Amblycorypha rivograndis:
I highly recommend adding some flowering plants to the cage. Amblycorypha rivograndis will enjoy them.
Adult male and adult female on flowers in cage:
FOOD
As with my other Amblycorypha species, I provided native plants in 4-inch pots as well as organic Romaine lettuce, organic apple slices, rolled oats, cricket powder, pecan/walnut/almond slices, nectar sponges, and fresh water.
Here is an Amblycorypha rivograndis adult female and adult male eating lettuce:
Here is an Amblycorypha rivograndis adult male eating apple:
Here is an Amblycorypha rivograndis adult male munching on cricket powder:
Here's an Amblycorypha rivograndis adult female munching on oats:
Here are very young nymphs on lettuce:
Here is a
VIDEO of an Amblycorypha rivograndis male that I had just brought home who was very, very hungry. He immediately found the lettuce and started chomping away.
Life Cycle (Incomplete Metamorphosis, overwintering as eggs) and F2-generation Update
EGG
The eggs of Amblycorypha rivograndis are cream- to tan-coloured, flattened, and oval-shaped and measure 4 to 4.5 mm.
Compared to the Amblycorypha huasteca egg, the A. rivograndis egg is about 1 mm shorter.
NYMPH
My first Amblycorypha rivograndis from overwintered eggs hatched on April 20, 2022. They continued hatching for the next couple of weeks. I did get one very late baby, however, who hatched on July 2, 2022.
I do not know how many instars nymphs go through, but I would guess six or seven.
What surprised me most about Amblycorypha rivograndis nymphs is that many, but not all, present irregular purple markings on their abdomens as well as on their legs. At first I thought something was wrong with my purple-blotched nymphs, but they turned out just fine, becoming completely green with the final moult to adult.
Nymph showing purple (male):
Here are examples of just-born Amblycorypha rivograndis, all on their first day after hatching. These young nymphs have distinctive purple markings on their legs:
Here is a just-born Amblycorypha rivograndis with an older nymph:
And another just-born nymph:
First-instar nymph:
Nymph getting bigger:
Here are late-instar nymph males:
Here's a late-instar nymph female:
This female nymph is in final instar:
ADULT
It took seven to eight weeks for my Amblycorypha rivograndis to moult to full adult after hatching.
Adult female and adult male and both sexes together:
aduult male:
Most adults lived two to three months after moulting to full adult. My final F1 generation adult died on December 9, 2022.
MOULTING:
With a successful moult, the nymph or newly emerged adult generally eats the exuvia.
Here is a newly moulted female nymph eating the exuvia:
As with most of my species, the most likely cause of premature death is a failed moult. Unfortunately, I saw several failed moults in Amblycorypha rivograndis, usually resulting in death or in less severe cases, disfiguration.
These are two examples of failed moults:
Here is an exuvia from a freshly moulted male:
UPDATE for MY F2 GENERATION, 2023
After overwintering the soil substrate dishes from my 2022 adults (along with the dishes from 2021), I was able to get an F2 generation of nymphs in 2023. My first nymph was born early in the season on March 2, 2023. The latest-born nymph of 2023 hatched on May 10, 2023. Most of my nymphs hatched in late April.
My final F2 adult (male) died on September 4, 2023.
Song
The SINA (Singing Insects of North America) site includes
an example of the Amblycorypha rivograndis song.
This is a
Sound-only VIDEO of the song recorded from my handraised A. rivograndis.
Here's a
Sound-only chorus of Amblycorypha rivograndis and other singers.
Mating, Spermatophylax, Laying Eggs
MATING
Mating – what mating? I never got to observe these guys mating. Even so, I have a strong suspicion that they do.
As with
Amblycorypha huasteca, I believe the cerci play no role in mating.
Images of cerci and subgenital plate of Amblycorypha rivograndis:
SPERMATOPHYLAX
I frequently saw Amblycorypha rivograndis females with an attached spermatophylax.
This female continues to walk around with the spermatophylax attached, and she does not consume it:
Close-ups of spermatophylax attached to female:
Discarding Spermatophylaces:
As with Amblycorypha huasteca, I have observed that Amblycorypha rivograndis also frequently discard spermatophylaces, pulling them off and abandoning them.
(See
Discussion of A. huasteca.)
Discarded spermatophylax of Amblycorypha rivograndis:
Comparison of Spermatophylax: Amblycorypha rivograndis vs. Amblycorypha huasteca (larger):
LAYING EGGS
I have never observed Amblycorypha rivograndis laying eggs, but I have a strong suspicion that they do.
The loose eggs that I found were in the bottom of the cage. It's most likely that these guys lay eggs in soil. I suppose there's a possibility that they lay eggs in stems of plants, but I would guess that they use soil as do species of the Amblycorypha oblongifolia group. With the ones I raised, eggs hatched the following spring. I had overwintered both their potted plants and their soil substrate dishes, keeping them in a "holding cage." Then in spring, I simply removed newly-hatched nymphs to a proper rearing cage, checking the holding cage each morning for new ones.
Observations
Compared with Amblycorypha huasteca, the A. rivograndis is quite a bit smaller:
(A. rivograndis on left: note the prototal spots)
Dead specimens:
These guys are a joy to raise. The nymphs are exceptionally beautiful with their purple markings. The song is fairly quiet, and since I had a room full of much louder singers, it wasn't until the end of the season that I got to hear these guys. I was only able to get one recording that wasn't drowned out by other singers.
Amblycorypha rivograndis in captivity spend most of their time on their plants, walking around and perching on broad leaves. Besides munching on their plants, they appeared to most enjoy eating Romaine lettuce.
These katydids are very easy to raise and are quite tolerant of me when I am cleaning their cage and changing out food. Unlike other genera, Amblycorypha are not likely to fly out of the cage. They should be provided with large cages and with a good supply of fresh food on a daily basis. Amblycorypha species are suitable for folks new to rearing.
References
Walker, T. J. (2004). The uhleri Group of the Genus Amblycorypha (Orthoptera: Tettigoniidae): Extraordinarily Complex Songs and New Species. Journal of Orthoptera Research, 13(2):169-183 (2004). https://www.jstor.org/stable/3503720
Walker, T. J. Rio Grande virtuoso katydid Amblycorypha rivograndis (Walker 2005). Singing Insects of North America. https://orthsoc.org/sina/010a.htm
A Few General Resources
Gwynne, D. T. (1986, September). Courtship feeding in katydids (Orthoptera: Tettigoniidae): Investment in offspring or in obtaining fertilizations? The American Naturalist. https://www.journals.uchicago.edu/doi/abs/10.1086/284566
Lehmann, G. U. C. (2012, August 15). Weighing costs and benefits of mating in bushcrickets (Insecta: Orthoptera: Tettigoniidae), with an emphasis on nuptial gifts, protandry and mate density - frontiers in zoology. Frontiers in Zoology. https://frontiersinzoology.biomedcentral.com/articles/10.1186/1742-9994-9-19
Lewis, S., & South, A. (2012, June 7). The evolution of animal nuptial gifts. Advances in the Study of Behavior. https://www.sciencedirect.com/science/article/abs/pii/B9780123942883000022
Simmons, L. W. (1995, August 1). Courtship feeding in katydids (Orthoptera: Tettigoniidae): Investment in offspring and in obtaining fertilizations: The American naturalist: Vol 146, no 2. The American Naturalist. https://www.journals.uchicago.edu/doi/abs/10.1086/285801?journalCode=an
Walker, T. J. (2004). The uhleri Group of the Genus Amblycorypha (Orthoptera: Tettigoniidae): Extraordinarily Complex Songs and New Species. Journal of Orthoptera Research, 13(2):169-183 (2004). https://www.jstor.org/stable/3503720
Walker, T. J. Rio Grande virtuoso katydid (Amblycorypha rivograndis). Singing Insects of North America. https://orthsoc.org/sina/010a.htm
Walker, T. J. Uhler's virtuoso katydid (Amblycorypha uhleri). Singing Insects of North America. https://orthsoc.org/sina/014a.htm
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A very special thank you to Brandon Woo who discovered these guys inhabiting an area of Bryan, Texas, and introduced me to this beautiful species.
And a very special thank you to Wil Hershberger who so kindly created spectrograms of our recorded songs in order to identify this species and distinguish it from the very similar Amblycorypha uhleri. Thank you for your patience in explaining the song differences to me and for your expertise that you so generously share with both experts and rank amateurs like myself.
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