Amitermes lilloi, Rocha & Cancello, 2020

Rocha, Mauricio M. & Cancello, Eliana M., 2020, Comparative anatomy of the gut of the South American species of Amitermes, with description of two new species and an identification key based on soldiers and workers, Zootaxa 4751 (1), pp. 75-104 : 98-102

publication ID	https://doi.org/ 10.11646/zootaxa.4751.1.4
publication LSID	lsid:zoobank.org:pub:778B13DA-851C-4CE8-B283-08B8F07E997A
DOI	https://doi.org/10.5281/zenodo.3718074
persistent identifier	https://treatment.plazi.org/id/987B995A-FFFE-FFF2-FF51-FF08FEC2FC82
treatment provided by	Plazi
scientific name	Amitermes lilloi
status	sp. nov.

Treatment

Amitermes lilloi sp. n.

Holotype. Soldier, part of lot MZUSP 8156 View Materials , 30.i.1964, W. Weyrauch col.

Type-locality. Tapia municipality, Province of Tucumán, Argentina.

Paratypes. ARGENTINA. Tucumán: Tapia. 30.i.1964 , W. Weyrauch (8156), 11.x.1965 (8155) , 01.ix.1965 (8157, 8158).

Etymology. Named in honor of Professor Miguel Lillo, a prominent Argentine naturalist who was born in Tucumán, the type locality of the species.

Soldier (Figs. 27C, 27D, 33C): Head nearly rectangular; in profile, top of head convex from posterior margin to middle, followed by prominent depression distally (Fig. 27D); labrum rounded, slightly angled at apex; postmentum elongated and with sinusoidal margins. Mandibles arched inward, with continuous curvature, narrowing to apex, conspicuous marginal teeth, slightly turned backward (Fig. 33C). Antennae with 14 articles. Anterior and posterior margins of pronotum rounded. Head with scattered bristles dorsally and laterally, denser around frontal pore opening; labrum with 8–10 bristles, longest pair apically; pronotum with bristles concentrated at anterior and posterior margins; abdomen with dense bristles distributed dorsally and ventrally, and short bristles ventrally; legs with sparse bristles. Measurements (10 individuals, from four colonies, in millimeters), CLM: 0.90–0.95, LH: 1.45–1.50, WH: 1.03–1.08, LT: 0.90–0.98.

Worker mandibles ( Fig. 28B View FIGURE 28 ): With typical xylophagous pattern. Left mandible: apical tooth slightly larger than M1+2, M3 easily recognizable, with marked cutting edge between marginal teeth; molar tooth hidden by molar prominence; molar prominence with marked ridges. Right mandible: apical tooth larger than M1, M2 easily recognizable, with marked posterior cutting edge, and molar plate with four marked ridges.

Gut anatomy ( Figs. 22D View FIGURE 22 , 23E View FIGURE 23 , 29B, 30B, 32): Crop asymmetrical, with oesophagous insertion displaced to left side, covered internally with pectinate scales before gizzard. Gizzard of the generalized type, with columnar and pulvillar belts subequal in length; first-order pulvilli conspicuous, with tiny pectinate scales, second-order pulvilli reduced (Fig. 29B). Stomodeal valve inserted in apex of mesenteron. Mesenteric tongue internal to mesenteric arch, narrower proximally and gradually enlarging to tip (Figs. 32C, 32D). P1 slightly larger than previous segment and tubular, crossing abdomen diagonally in dorsal view, over paunch (P3), inserted in a clearly visible enteric-valve seating, dorsally and at right side of abdomen, occluded by P4 segment (Fig. 32E, arrow, P4 removed). P1 cuticular ornamentation composed of sparse small spines around mesenteric tongue at mixed segment, followed by elongated area of spines with sclerotized base located proximally ( Figs. 22D View FIGURE 22 , 23E View FIGURE 23 ). Enteric-valve armature (P2) composed of six digitiform cushions ornamented with small spines, denser in distal portion (Fig. 30B). P3 well developed, with a conspicuous enteric-valve seating (Fig. 32E). Isthmus clearly recognizable. Fourth proctodeal segment (P4) with short U-turn and located dorsally (Fig. 32A).

Comparisons: A. lilloi can be easily distinguished from all other South American members of Amitermes by the well-marked enteric-valve seating (Fig. 32E), which is clearly visible, even in the soldier caste. Regarding the soldiers, in A. aporema the marginal teeth are absent or poorly marked (Figs. 11A, 11C); the mandibles of A. excellens has more-elongated and a less pronounced curve, with the marginal teeth located proximally ( Fig. 15C View FIGURE 15 ); and A. bandeirai , A. beaumonti and A. lunae have fishhook-shaped mandibles (Figs. 27C, 15A, 15G). Amitermes lilloi , sp. n. shares the same marked marginal teeth, with the general slender shaped mandible with A. amicki , A. amifer and A. foreli ( Figs. 1A, 1C View FIGURE 1 , 15E View FIGURE 15 ). Amitermes lilloi can be distinguished from A. foreli by its size (consistently smaller) and by their distributions (Figs. 26, 31); and differs from A. amifer in the mandibles, which are more slender and larger proportionally in the new species, with more-acute marginal teeth (Figs. 33A, 33C).

Key to South American species of Amitermes based on soldiers and workers

1 Distal portion of soldier mandible fishhook-shaped ( Figs. 15A, 15G View FIGURE 15 , 27A, 33B).................................... 2

- Distal portion of soldier mandible slender, not fishhook-shaped ( Figs. 1A, 1C View FIGURE 1 , 3 View FIGURE 3 , 11A, 11C, 15C, 15E, 27C)............. 4

2 Length of distal portion of P1 short ( Figs. 4B View FIGURE 4 , 17E View FIGURE 17 ).......................................................... 3

- Length of distal portion of P1 elongated ( Figs. 25A, 25B View FIGURE 25 ); found in western South America, in very dry environments (Fig. 26).......................................................................................... A. lunae

3 Very thin soldier mandibles with a sharp backward directed teeth ( Fig. 15A View FIGURE 15 ); found in Central America ( Fig. 14 View FIGURE 14 )................................................................................................... A. beaumonti

- Robust soldier mandibles with a strongly inward curved distal half, with conspicuous teeth backward directed (Figs. 27A, 33B); found in eastern South America, commonly in Atlantic Forest vegetation formations ( Fig. 31 View FIGURE 31 )................ A. bandeirai

4 Dilated portion of P1 fusiform ( Figs. 2D View FIGURE 2 , 4D View FIGURE 4 , 12D, 13D, 32D), mesenteric tongue strangled proximally ( Figs. 2A View FIGURE 2 , 4A, 4E View FIGURE 4 , 12A, 13A, 32A)........................................................................................... 5

- Dilated portion of P1 well developed and globose ( Figs. 19D View FIGURE 19 , 21D View FIGURE 21 ), mesenteric tongue broad and evenly wide along entire length ( Figs. 19B View FIGURE 19 , 21B View FIGURE 21 )................................................................................ 6

5 Soldier marginal teeth marked ( Figs. 1A, 1C View FIGURE 1 , 27C, 33A, 33C), P4 dorsally located ( Figs. 2A View FIGURE 2 , 4A View FIGURE 4 , 32A)................. 7

- Soldier marginal teeth absent or poorly marked (Figs.11A, 11C), P4 displaced to right side of body (Figs. 12A, 13A).................................................................................................. A. aporema

6 Position of marginal teeth close to base of soldier mandible ( Fig. 15C View FIGURE 15 )................................... A. excellens

- Position of marginal teeth at midlength of soldier mandible ( Fig. 15E View FIGURE 15 )...................................... A. foreli

7 P3 seating not marked ( Figs. 2D View FIGURE 2 , 4D View FIGURE 4 )..................................................................... 8

- P3 seating marked (Fig. 32C, 32E).................................................................. A. lilloi

8 In profile, thick (or high) soldier head with a curved dorsal margin covered by long bristles densely distributed ( Fig. 1B View FIGURE 1 ); occurrence in dry environments in northern Venezuela and Colombia (Fig. 9).................................. A. amicki

- In profile, narrower soldier head with a dorsal margin with only slightly curved and covered by bristles sparsely distributed ( Fig. 1D View FIGURE 1 ); occurrence in open environments of South America, part of the dry diagonal biomes (Caatinga, Cerrado and Chaco) in Brazil, Paraguay, Bolivia and Argentina (Fig. 9)..................................................... A. amifer

FIGURE 34. Detail of Amitermes sp. worker gut (crop and first half of mesenteron removed); arrow: whitish area on P3 wall. Discussion