F. M. Carpenter.
The Supposed Nymphs of the Palaeodictyoptera.
Psyche 55(1):41-50, 1948.

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THE SUPPOSED NYMPHS OF THE
PALBODICTYOPTERA1
BY F. M. CARPENTER
Harvard University
Our knowledge of the metamorphosis of Carbonifer- ous insects is meager. Inferences have been made about their immature stages, but actual knowledge is restricted to the fossils which have been found. Fur- thermore, although some Carboniferous nymphs are known, it is difficult to associate them with adults. Spe- cific association is obviously impossible; the best that can be done is association by family or order. If the fossils concerned are members of an existing order, the association can be made with near certainty, for the living immature and imaginal forms provide a basis for comparison; but if the fossils are adults belonging to an extinct order, the problem of identifying their imma- ture stages is more difficult. This is well illustrated by the nymphs which have been referred to the extinct order Palseodictyoptera, and which have been extensively dis- cussed in the literature on wing development. Specu- lation about these nymphs and their significance has been so great that I have thought it worth-while to summarize here what is actually known about them.
Five palaeodictyopterous nymphs have been described up to the present time, four by Handlirsch (1906) and one by Goldenberg (1873). All are from Carboniferous strata. Through the courtesy of Dr. R. S. Bassler and Dr. G. A. Cooper, I have been able to examine the four Handlirsch specimens in the United States National Mu- seum. I have not seen the Goldenberg fossil, which is in the collection \')f the Natural History Society at Bonn, Germany, but it has been redescribd and figured by v. Schlechteqdal (1913) and Guthorl (1934). Handlirsa placed all these species in the "form genus" Pal<sodic- tyopteron, but he also used that term as a generic name 1 Published with a grant from the Museum of Comparative Zoology at Harvard College.
41
Pu&e 55:41-51 (1948). hup ttpsychu einclub orgt55t55-IMLhtinl



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42 Psyche [Mar.
for adult Palaeodictyoptera with obscure family relation- ships. Since, for reasons given below, I consider their ordinal position obscure, I have assigned these nymphs to Insecta Incertae Sedis.
Insectorurn gen. indet. anglicanum Handl. Plate 6, figures 1 and 5; plate 7, figure 1. (Palceodictyopteron} a~licamirn Handlirsch, 1906, Foss. Ins.: 52, pi. 8, fig. 16.
The specimen on which this species is based is pre- served in an ironstone nodule, from Sedgley, England, and is now in the U. S. National Museum (Type no. 38109, Beale Collection). Handlirsch's figure of the fos- sil, which is reproduced here (plate 6, figure 1) depicts a slender wing or wing-pad, a fragment of another, parts of the head (including one compound eye), thorax and abdomen. The wing-pad is shown extending laterally from the thorax, its longitudinal axis being perpendic- ular to the longitudinal axis of the thorax. This figure has been referred to several times in entomological literature and has caused much speculation about the development of the Palaeodictyoptera. Comstock, in his ' ' Wings of Insects " (1918), refutes Handlirsch 's con- tention that immature Palaeodictyoptera were aquatic by pointing out that it would be "difficult to imagine insects with laterally projecting wing buds, such as these nymphs possessed, swimming through the water." Lemche (1940) uses the same figure as a source of important evidence to aid his theory of polyphylectic origin of wings in insects. Similarly, Forbes (1943) has employed it to support his erection of an extinct order, Anasaxia. The Palaeodictyoptera differed from the Anasaxia, in part, by having nymphs "with the wing-pads extending directly out, unlike allother insects. ' '
^
The fossil responsible for all this speculationis poorly preserved, as shown in the accompanying photograph (plate 7, figure 1). So far as I have been able to deter- & -
mine, it consists only of a 'single wing or wing-~ad and suggestions of the abdomen plate 6, figure 5): "The tho- ^
rax and head are not disce nTble and the object which



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lg4a Carpenter-Palaeodictyopterous Nymphs 43 Handlirsch identified as an eye is plant material, like that covering most of the nodule.
There is therefore no
evidence whatever that the wing-pads of this insect were developed perpendicularly to the thorax. The wing it- self, however, shows more details than are indicated in Handlirsch's figure or description. It is about 7 mm. long, with an anterior margin that is slightly concave proximally and convex near the middle. The most ob- vious feature of the wing is a prominent longitudinal ridge (or groove, in the counterpart), which is probably the radius (Rl). Between it and the anterior margin is a weaker interrupted ridge, and posterior to it is what appears to be a forked vein.
There is also a suggestion
of a posterior submarginal vein.
The part of the abdomen that is preserved consists of five or six broad segments. These few segments indicate an abdomen that is large in proportion to the wing,-a peculiarity suggesting that the insect was a nymph. This was probably the case, but there is another possi- bility worth mentioning: the wing of the fossil is much like the elytron of some Protelytroptera, even to the con- cave anterior margin, the heavy Rl, and the posterior, submarginal vein. Without more -precise knowledge of the fore wing and at least part of the hind wing, we can reach no conclusion on the ordinal position of this fos- sil. There is certainly nothing to show that it is palaeo- dictyopterous, and Handlirsch, although describing the specimen as a nymph of that order, gave no reason for his conclusion.
Insect orum gen. indet. virgimanum Handl. Plate 6, figure 2; plate 7, figure 2.
,
(Palceodictyoptem) virginianum Handlirsch, 1906, Foss. Ins. : 63, pi. 8, fig. 19; 1906, Proc. U. S. Nat. Mus., 29: 689, fig. 16.
The type of this species is preserved in black shale, from soft coal beds near Redbird, West Virginia, and is now in the National Museum (No. 25635). Handlirsch's drawing of the fossil is reproduced here (plate 6, figure



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44 Psyche [Mar.
2) ; it depicts a basal piece of the fore wing-pad, a com- plete hind wing or its bud, and fragments of the thorax and abdomen. As in the case of the preceding species, the figure shows the wings extending laterally from the thorax, and it was reproduced by Comstock (1918, fig. 81) to demonstrate the lateral formation of wings in palaeodictyopterous nymphs.
Examination of the fossil convinces me that Hand- lirsch, in making his drawing, confused plant remains with those of the insect, as can be seen from the ac- companying photograph '(plate 7, figure 2). . The frag- ment of the fore wing represented in his figure is either a piece of a plant or of the insect's body ; it is dearly not a wing or wing-bud, and it bears a relationship to the true wing different from that shown in his figure. The parts of the "thorax" and "abdomen" are clearly of plant origin. The wing itself is about 10 mm. long, and much more oval than shown in Handlirsch's figure. There are faint indications of veins or ridges, but they cannot be followed satisfactorily because of numerous wrinkles. Although this wing is very different from that of the foregoing insect in shape, size and texture, there is no evidence that it was either palseodictyopterous or a nymphal structure.
Insectorurn gen. indet. mazonum Handl.
Plate 6, figure 3.
(Palceodictyopteron) masom Handlirsch, 1906, Foss. Ins. : 63, pi. 8, fig. 17; 1906, Proc. U. S. Nat. Mus., 29 : 688, fig. 14.
This is preserved in an ironstone nodule, from the vicinity of Morris, Illinois (Type no. 38831, U. S. National Museum). Handlirsch's figure is correct in depicting the distal part of a wing, 18 mm. long, which could be either nymphal or mature. The apparent thick- ness of the fossil suggests that it is a wing-pad, possibly of a roach or Protorthopteron. Its assignment to the Palaeodictyoptera is entirely without foundation and Handlirsch gave no reason for placing it there.



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19481 Carpenter-Palaeodictyopterous Nymphs 45 Insectorum gen. indet. latiperne Handl.
Plate 6, figure 6.
(Palaodictyopteron) latiperne Handlirsch, 1906, Foss. Ins. : 63, pi. 8, fig. 18; 1906, Proc. U. 8. Nat. Mus., 29; 688, fig. 15.
This is also preserved in an ironstone nodule of the Carbondale Formation, from near Braidwood, Illinois (Type no. 38838, U. S. National Museum). As Hand- lirsch shows, it consists of a poorly preserved wing, 22 mm. long, with a distinctly enlarged anal area. There is no sign of the body and the only suggestion that the fos- sil is a nymphal wing lies in its apparent thickness. There is nothing, however, to show that it is palmdic- tyopterous; it could have belonged as well to a nymph of a Protorthopteron or a related Carboniferous order. Insectorum gen. indet. Jzageni Gold.
Plate 6, figure 4.
Termes Jzageni Goldenberg, 1873, Fauna sarsep. foss., 1: 12 ; pl. 2, fig. 7b.
(Palc~odictyopteron} hagem Handlirsch, 1906, Foss. Ins. : 62, pi. 8, fig. 15; v. Schlectendal, 1913, Nova Acta Leop., 98: 99, pi. 1, fig. 7; pi. 8, fig. 1. (Dictyoneuridffi) hageni Guthorl, 1934, Preuss. Geol. Landes., 164 : 84, fig. 48 ; pi. 13, fig. 6. This fossil, from the Saarbrucken beds of Germany, was originally thought by Goldenberg to be a wing of a termite. It has subsequently been examined and de- scribed by Handlirsch, v. Schlectendal, and Guthorl, who have considered it a palaeodictyopterous wing-pad. The discrepancy in the figures of the three last workers is astonishing. Handlirsch shows a complete wing, with entire margins ; v. Schlectendal, a wing fragment, the wing being broken posteriorly and distally; Guthorl, a wing fragment with all margins broken. Guthorl's and v. Schlectendal's figures are alike in venation, but differ markedly from Handlirsch's. From these and the pho- tographreproduced by Guthorl, the fossil appears to be a proximal fragment (9 mm. long) of a small wing, pos-



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46 Psyche [Mar.
sibly a wing-pad; but there is nothing to show its af- finities.
From the foregoing account I believe it is clear that none of the fossils described as palaeodictyopterous nymphs can rightly be so considered until further evi- dence is at hand. Consequently, we have no actual record of the nymphs of these insects and no knowledge whatever of their wing development. It is noteworthy, in this connection, that nymphs of the related order Megasecoptera have been described by Handlirsch (1911), from Illinois, and Bolton (1921) from England. Those studied by Bolton show a venational pattern strongly resembling that of the adult insects of the family Brodiidse, and since both adults and nymphs occur in the same deposit, their association seems justi- fied. Handlirsch's (Palceodictyopteron} anglicanurn, which has been discussed above, may be a poorly pre- served and distorted specimen of this type. His me- gasecopterous nymph, from the vicinity of Mazon Creek, is so much like Bolton's that its assignment to the Me- gasecoptera is highly probable. At any rate, none of these nymphs, which, incidentally, show the usual type of wing development, can be referred to the Palseo- dictyoptera. For the present, therefore, we remain in complete ignorance of their immature stages. LITERATURE CITED
BOLTON, H.
1921.
A Monograph of the Fossil Insects of the British Coal Mea- sures, Part. I. Palseont. Soc., 1919: 1-80. FORBES, W. T. M.,
1943.
The Origin of Wings and Venational Types in Insects. Amer. Midi. Nat., 29: 318-405.
GOLDENBERG, F. I
1875. Fauna Sarsepontana Fossilis. Die fossilen Thiere aus der Steinkohlenf ormation von Saarbrucken, 1 : 1-26. GUTHORL, P.
1934. Die Arthropoden aus dem Carbon und Perm des Saar-Nahe- Pfalz-Gebietes.
Abhandl. Preuss. Geol. Landes., 164 : 1-219. HANDLIRSCH, A.
1906. Die fossilen Insekten. Leipzig.
1911. New Palseozoic Insects from the Vicinity of Mazon Creek, Illinois.
Am. Journ. Sci., 31 (4) : 353-377.
1922. Insecta palseozoica. Foss. Cat., 16 (1) : 1-230.



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19481 Carpenter-Palaeodict yopt erous Nymphs LEMCHE, H.
1940. The Origin of Winged Insects. Vidensk. Medd. fra Dansk. Naturh. Foren., 104 : 127-168.
v. SCHLECHTENDAL, D.
1913. Untersuchungen iiber die karbonischen Insekten und Spinnen von Wettin unter Berucksichtigung verwandter Faumen. Erster Teil: Revision der Originale von Germar, Giebel und Goldenberg. Abhandl. Leop.-Carol. Deutschen Akad. Naturf., 98: 1-186.




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Psyche
[Mar.
Fig. 1. -Insectorurn, gen. indet. anglicanurn Handl. From Handlirsch, 1906. Fig. 2. Insectorurn gen. indet. virginianurn Handl. From Handlirseh, 1906. Fig. 3. Insectorurn gen. indet. inasonurn Handl. From Handlirsch, 1906. Fig. 4. Insectorzm gen. indet. Jzageni Gold. From GuthGrl, 1934. Fig. 5. Insectorum gen. indet. anglicanurn Handl. Original drawing, based upon type.
Fig. 6. Insectorurn gen. indet. latipenne Handl. From Handlirsch, 1906.



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19481 Carpenter-Palaedictgopterous Nymphs 49



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[Mar.
Fig. 1. Photograph of the type of Insectorum gen. indet. anglicanum Handl. (U. S. Nat. Museum, no. 38109).
Fig. 2. Photograph of the type of Insectorum gen. indet. virginianum Handl. (U. S. Nat. Museum, no. 25635).




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