nomos LXXVIa

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Organic Evolution in terms of the Implicate and Explicate Orders.

Part LXXIIa

Diptera (midges, mosquitoes, flies) (IVa)

The evolutionary diversification in the Order Diptera revisited.

Derivational Lines, Morphoklines, and Polyphyletic evolution, of stratiomyoid wings

Derivational lines connecting wing-venations of the stratiomyoid functional type

First derivational line :

Rhagio scolopaceus, Rhagionidae.
Subcosta (SC) well developed. Radial Sector (RS) 3-branched. R3 absent. Discoidal cell present.
The cross-vein ta [= r-m] present in its original condition. M1, M2, M3, and M4 present. tb1 [= base of M4] present. tb2 [= m-cu] present. CuA [labelled as cu1b in the Figure] present. 1A [in the Figure labelled as 1a] present, reaching wing-margin near end of CuA. No further anal veins present.

Solva marginata, Solvinae, Stratiomyiidae.
R3 absent (as in Rhagio).
Trunk of M still in a clearly developed condition.
M1 and M2 present. M3 and M4 with short common end-stalk. CuA and 1A with common end-stalk.

Craspedometopon frontale, Stratiomyiidae.
R3 absent (as in Rhagio).
R2, R4, and R5, shifted towards the anterior wing-margin (costalization).
Trunk of M bleak (according to HENNIG, 1954).
M1 and M2 present. M3 absent. M4 present, reaching wing-margin. CuA and 1A with common end-stalk.

Cibotogaster fumipennis, Stratiomyiidae.
R3 absent (as in Rhagio).
R2, R4, and R5, as in Craspedometopon, shifted towards the anterior wing-margin (costalization). Fork of R4+5 shortened.
Trunk of M bleak (according to HENNIG, 1954).
M1, M2, M3 and M4 present, each on its own reaching wing-margin. CuA and 1A with common end-stalk.

and without vein-labels and arrows :

Hermione locuples, Stratiomyiidae.
R3 absent (as in Rhagio).
R2, R4, and R5, still further shifted towards the anterior wing-margin (costalization). Fork of R4+5 shortened.
Trunk of M bleak (according to HENNIG, 1954).
M1, M2, M3 and M4 present, each on its own, but not reaching wing-margin (also a feature of the costalization of the venation). CuA and 1A with common end-stalk.

Chiromyza vittata, Stratiomyiidae.
R3 absent (as in Rhagio). R4 absent. So RS has become 2-branched (instead of 3-branched). Trunk of M bleak (according to HENNIG, 1954). M1, M2, and M4 present, each on its own reaching wing-margin. M3 present as a short remnant only. CuA and 1A with common end-stalk.
This form is, because of the more primitive course of R5, and the long R2, not strictly derivable from any of the previous three forms. It may be derivable directly from Solva (2nd member of the present derivational line).

Corresponding Diagram of Morphoklines :

* * *

Second derivational line :

Introductories.
This line involves species of the family Cyrtidae. It somehow comes from certain Nemestrinidae such as Hirmoneura bellula :

Departing from the latter, the wing-venation in the Cyrtidae then might (following HENNIG, 1954) originate in the following way through one hypothetical transitional form to true cyrtid venation :

Figure above : Schemes clarifying a hypothesis of the origin of the wing-venation in Cyrtidae. Cells indicated by capital letters.
200 - Initial condition (compare with Hirmoneura above) : R3 in approximately normal position, but doesn't end up in R4, but in the common stalk of the fork R4+5. The latter has shifted more or less close to the anterior margin (M1+2) of the discoidal cell, and is still connected with it by the radio-medial cross-vein ta. The strong arrows indicate the direction in which R3 and R4+5 are being displaced, until the situation as drawn in 201 has been reached.
201 - Groundplan of the venation in Cyrtidae (Compare with next Figure) : R4+5 finally positioned at the anterior margin (M1+2) of the discoidal cell and coalesced with it. Therefore the radio-median cross-vein ta totally suppressed. The two seemingly radio-median cross-veins are in fact the still free basal and apical sections of R4+5. R3 has moved into the old bed of R4+5 and has re-activated it. The old bed of R3 is re-activated by a short vein-stump [R4+5 now runs along the discoidal cell, and in the original bed of R4+5 now runs R3 (above the discoidal cell]. (After HENNIG, 1954 (figures 200 and 201))

202 - Lasia aenea Phil., Cyrtidae. 203 - Eulonchus tristis Lw., Cyrtidae. (Cells are indicated by capital letters). [Of course these two cyrtid wings do not belong to the stratiomyoid functional wing-type, - only cyrtid wings with more reduced venation belong to that type.] (After HENNIG, 1954)

Now then the (second) derivational line :

Hirmoneura bellula, Nemestrinidae.
R3 present as a short vein running from R4 to R2. The cross-vein r-m (ta) almost suppressed by the anterior part of the discoidal cell (which part is M1+2). The veins SC, R1, R2, R4, R5, M1, and M2 running closely parallel to each other to the apical part of the wing. Also M4 runs in the same direction. [The course of all the mentioned veins is therefore strongly d e r i v e d with respect to the course of these veins in Rhagio]. Extra cross-veins are present between R5 and M1, and between M1 and M2. M3 present as a very short vein between M2 and M4. The veins M3 and M4 form a common end-stalk ending at the posterior margin of the wing. CuA and 1A end up close together at the wing-margin. Wing more or less elongate.
A pseudo longitudinal vein has developed (seen in most, if not all, Nemestrinidae) running from the base of RS obliquely to the hind-margin of the wing. This vein is composed of parts of other veins : base of RS, R4+5, apical section of M1+2, basal part of M2, basal part of M3, and common stalk of M3 and M4. As in all Nemestrinidae the basiala is large, provided with a strong phragm.

Lasia aenea, Cyrtidae.
R2 present. Below it, parallel to the anterior margin of the discoidal cell, runs R3. So it is assumed that the origin of this vein has been shifted significantly into the direction of the wing-base as compared with Hirmoneura (and almost all other related forms). From the bifurcation-point of R2+3 (resulting in R2 and R3) R4+5 departs, but soon coalesces with the anterior margin (M1+2) of the discoidal cell, and separates beyond it again, splitting up in R4 and R5.
M1 and M2 separately run to the wing-margin, without, however, reaching it.
M3 and M4 with common end-stalk as a result of the bending of M3 toward M4 (as also in Hirmoneura and others). Base of M4 present, but very short [indicated in the figure by tb]. The cross-vein m-cu present, connecting CuA [indicated as cu1b in the figure] and M4.
CuA and 1A with common end-stalk (and not yet so in Hirmoneura).
As regards the basiala, both in Hirmoneura and in Lasia the alula and the phragm are well developed (the phragm is the strong oblique vein strut in the proximal radial region at about the level of the humeral cross-vein [between C and SC] ).
So all in all, the venation of Lasia is more or less well derivable from that of Hirmoneura, but not typically and exclusively so.

Eulonchus tristis, Cyrtidae.
Virtually the same venation as in Lasia, but M1 and M2 both reaching wing-margin, and base of wing narrowed.

Cyrtus pusillus, Cyrtidae.
Free end-section of R4+5 recurrent and relatively long.

Opsebius diligens, Cyrtidae.
Free end-section of R4+5 recurrent and relatively long, as in Cyrtus. M3 reduced, present only as a short stump. M1, M2 and M4 present, reaching wing-margin. Wing-base narrowed.

Corresponding Diagram of Morphoklines :

* * *

The remaining Cyrtidae have strongly reduced venation, such that they belong to the stratiomyoid functional wing-type. Each one of them (judging from HENNIG's figures, see Figure 3 of previous document) is an isolated venational specialization. So no derivational line(s) is (are) set up for them.

With all this we have concluded the functionality, venational derivation, and polyphyletic evolution of stratiomyoid wings.
In the next document we will discuss the wings of the Lifting Many-veined (empidoid) Functional Type (followed -- in the next-next document) by setting up the corresponding derivational lines and morphoklines.

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	Rhagio scolopaceus, Rhagionidae. Subcosta (SC) well developed. Radial Sector (RS) 3-branched. R3 absent. Discoidal cell present. The cross-vein ta [= r-m] present in its original condition. M1, M2, M3, and M4 present. tb1 [= base of M4] present. tb2 [= m-cu] present. CuA [labelled as cu1b in the Figure] present. 1A [in the Figure labelled as 1a] present, reaching wing-margin near end of CuA. No further anal veins present.
	Solva marginata, Solvinae, Stratiomyiidae. R3 absent (as in Rhagio). Trunk of M still in a clearly developed condition. M1 and M2 present. M3 and M4 with short common end-stalk. CuA and 1A with common end-stalk.
	Craspedometopon frontale, Stratiomyiidae. R3 absent (as in Rhagio). R2, R4, and R5, shifted towards the anterior wing-margin (costalization). Trunk of M bleak (according to HENNIG, 1954). M1 and M2 present. M3 absent. M4 present, reaching wing-margin. CuA and 1A with common end-stalk.
	Cibotogaster fumipennis, Stratiomyiidae. R3 absent (as in Rhagio). R2, R4, and R5, as in Craspedometopon, shifted towards the anterior wing-margin (costalization). Fork of R4+5 shortened. Trunk of M bleak (according to HENNIG, 1954). M1, M2, M3 and M4 present, each on its own reaching wing-margin. CuA and 1A with common end-stalk.
and without vein-labels and arrows :	Hermione locuples, Stratiomyiidae. R3 absent (as in Rhagio). R2, R4, and R5, still further shifted towards the anterior wing-margin (costalization). Fork of R4+5 shortened. Trunk of M bleak (according to HENNIG, 1954). M1, M2, M3 and M4 present, each on its own, but not reaching wing-margin (also a feature of the costalization of the venation). CuA and 1A with common end-stalk.
	Chiromyza vittata, Stratiomyiidae. R3 absent (as in Rhagio). R4 absent. So RS has become 2-branched (instead of 3-branched). Trunk of M bleak (according to HENNIG, 1954). M1, M2, and M4 present, each on its own reaching wing-margin. M3 present as a short remnant only. CuA and 1A with common end-stalk. This form is, because of the more primitive course of R5, and the long R2, not strictly derivable from any of the previous three forms. It may be derivable directly from Solva (2nd member of the present derivational line).

	Hirmoneura bellula, Nemestrinidae. R3 present as a short vein running from R4 to R2. The cross-vein r-m (ta) almost suppressed by the anterior part of the discoidal cell (which part is M1+2). The veins SC, R1, R2, R4, R5, M1, and M2 running closely parallel to each other to the apical part of the wing. Also M4 runs in the same direction. [`The course of all the mentioned veins is therefore strongly d e r i v e d with respect to the course of these veins in` Rhagio]. Extra cross-veins are present between R5 and M1, and between M1 and M2. M3 present as a very short vein between M2 and M4. The veins M3 and M4 form a common end-stalk ending at the posterior margin of the wing. CuA and 1A end up close together at the wing-margin. Wing more or less elongate. A pseudo longitudinal vein has developed (seen in most, if not all, Nemestrinidae) running from the base of RS obliquely to the hind-margin of the wing. This vein is composed of parts of other veins : base of RS, R4+5, apical section of M1+2, basal part of M2, basal part of M3, and common stalk of M3 and M4. As in all Nemestrinidae the basiala is large, provided with a strong phragm.
	Lasia aenea, Cyrtidae. R2 present. Below it, parallel to the anterior margin of the discoidal cell, runs R3. So it is assumed that the origin of this vein has been shifted significantly into the direction of the wing-base as compared with Hirmoneura (and almost all other related forms). From the bifurcation-point of R2+3 (resulting in R2 and R3) R4+5 departs, but soon coalesces with the anterior margin (M1+2) of the discoidal cell, and separates beyond it again, splitting up in R4 and R5. M1 and M2 separately run to the wing-margin, without, however, reaching it. M3 and M4 with common end-stalk as a result of the bending of M3 toward M4 (as also in Hirmoneura and others). Base of M4 present, but very short [indicated in the figure by tb]. The cross-vein m-cu present, connecting CuA [indicated as cu1b in the figure] and M4. CuA and 1A with common end-stalk (and not yet so in Hirmoneura). As regards the basiala, both in Hirmoneura and in Lasia the alula and the phragm are well developed (the phragm is the strong oblique vein strut in the proximal radial region at about the level of the humeral cross-vein [between C and SC] ). So all in all, the venation of Lasia is more or less well derivable from that of Hirmoneura, but not typically and exclusively so.
	Eulonchus tristis, Cyrtidae. Virtually the same venation as in Lasia, but M1 and M2 both reaching wing-margin, and base of wing narrowed.
	Cyrtus pusillus, Cyrtidae. Free end-section of R4+5 recurrent and relatively long.
	Opsebius diligens, Cyrtidae. Free end-section of R4+5 recurrent and relatively long, as in Cyrtus. M3 reduced, present only as a short stump. M1, M2 and M4 present, reaching wing-margin. Wing-base narrowed.