VATELLINI, Sharp, 1880

Miller, Kelly B., 2005, Revision of the New World and south-east Asian Vatellini (Coleoptera: Dytiscidae: Hydroporinae) and phylogenetic analysis of the tribe, Zoological Journal of the Linnean Society 144 (4), pp. 415-510 : 428-430

VATELLINI SHARP, 1882

Vatellini Sharp, 1882b: 258 (as group of Dytisci fragmentati); Régimbart, 1895: 11 (new status); Zimmermann, 1919: 124, 1920: 29 (as tribe of Hydroporinae); Leng, 1920: 76; Guignot, 1959: 59; Nilsson, Roughley & Brancucci, 1989: 312; Trémouilles, 1995: 24; Nilsson, 2001: 233; Roughley & Larson, 2001: 169.

Vatellinae, Omer-Cooper, 1958: 249.

Diagnosis: This tribe is defined as those Hydroporinae with the following combination of characters: (1) prosternal process not reaching metasternum (mesocoxae contiguous) ( Figs 21, 22 ), (2) abdominal sternum VI with an invaginated, heavily sclerotized gland (speleum) ( Figs 28–30 ) and (3) female with apically expanded and broadly truncated process at apex of spermatheca (e.g. Figs 60 , 186 ). The extinct species, Calicovatellus petrodytes , was proposed as the sisterspecies to the remaining members of the tribe as the metepisternum reaches the mesocoxal cavities ( Miller & Lubkin, 2001). A speleum and a triangular spermathecal process have not been observed in Calicovatellus , but the prosternal process does not reach the metasternum and the general body shape is characteristic of other members of the tribe. Extant species all possess a metepisternum with its medial apex covered by a lobe of the mesepimeron (the mesepimeron and the metasternum meet along the mesocoxal cavity).

Taxonomic history: This taxon was first erected as a group in Sharp’s (1882b) ‘Dytisci fragmentati’ based on the separation of the metepisternum from the mesocoxal cavities (at least externally). The tribe was placed in the Hydroporinae by subsequent authors ( Zimmermann, 1920; Balfour-Browne, 1940; Crowson, 1955). Omer-Cooper (1958) recognized the group at the rank of subfamily, but this has not been generally followed. The phylogenetic position of the group nested within the Hydroporinae was supported by Wolfe’s (1985, 1988) analyses, but relationships of this tribe to others within the Hydroporinae remains equivocal. Wolfe (1985, 1988) found M. mexicanus to be sister to a species of Oreodytes , but regarded this relationship as doubtful. The group was resolved with members of Hydroporini in a morphological analysis (Miller, 2001). Most recently, Biström & Nilsson (2003) proposed a close relationship between Derovatellus , Peschetius Guignot and Necterosoma McLeay. Prior to this revision there were 52 species (one species with a single subspecies) recognized in five genera (one genus with two subgenera). With this revision there are 57 species in the tribe in three genera. Changes include three genus-group synonymies, eight new species, one elevation of a subspecies to species rank, and four new species-group synonymies.

KEY TO THE GENERA OF VATELLINI

Adults

1. Metepisternum extending to mesocoxal cavity externally............... Calicovatellus Miller & Lubkin (extinct)

1¢. Metepisternum apparently not extending to mesocoxal cavity externally, separated from it by a lobe of the mesepimeron ( Fig. 20 )............................................................................ 2

2. Pronotum not cordate, variously rounded, widest at or posterior to middle (e.g. Figs 51 , 68 ); metacoxal lines moderately approximated throughout length, not or only slightly divergent anteriorly (e.g. Figs 52 , 97 ); metatrochanter with ventral (posterior) margin evenly curved, not emarginate and without prominent basal, circular lobe (e.g. Figs 53 , 98 ); size smaller, TL = 3.0–5.0 mm; male lateral lobes not basally extended, not fused ventrally (e.g. Figs 59 , 104 ); female spermatheca elongate, tubular, medially angulate (e.g. Figs 60 , 105 ); apical margin of ventral apex of orifice of speleum not lobed......................................................... Derovatellus Sharp

2¢. Pronotum variously cordate, widest anterior to middle (e.g. Fig. 1); metacoxal lines generally closely approximated posteriorly, strongly divergent anteriorly (e.g. Fig. 176 ); ventral (posterior) margin of metatrochanter with prominent medial emargination (e.g. Figs 267, 268 ); metatrochanter with prominent basal, circular lobe that extends medially over surface of metacoxa with leg in anterior position ( Figs 267, 268 ); size larger, TL = 4.5–7.5 mm; male lateral lobes in basal portion strongly extended and fused along ventral margin (e.g. Fig. 184 ); female spermatheca globular, subspherical (e.g. Fig. 186 ); apical margin of ventral apex of orifice of speleum distinctly lobed (e.g. Figs 180 , 222 )......................................................................... Vatellus Aubé

Larvae ( Calicovatellus unknown ) (adapted from Spangler (1966b))

1. Antennomeres II and III subequal in length and longer than other antennomeres; antennomere IV smallest, slightly less than half length of antennomere III.............................................. Derovatellus Sharp

1¢. Antennomeres I and II subequal in length and longer than other antennomeres; antennomere IV smallest, about oneseventh length of antennomere III........................................................ Vatellus Aubé

Figures

Figures 18–22. Hydroporinae species, morphology. 18, Hydroporus notabilis, left prothorax, left oblique aspect. 19–21, Vatellus grandis; 19, left prothorax, left oblique aspect; 20, left mesosternum, mesocoxa, metasternum and metacoxa, left oblique aspect; 21, mesosternum, mesolegs, metasternum and metalegs. 22, Derovatellus lentus, mesosternum, mesolegs, metasternum and metalegs. CxI, procoxa; CxII, mesocoxa; FeI, profemur; FeII, mesofemur; Msem, mesepimeron; Mses, mesepisternum; Msst, mesosternum; Mtes, metepisternum; Mtst, metasternum; Prel, pronotal epipleuron; Prpl, propleuron; Prpo, prosternal pore; Prpr, prosternal process; Prst, prosternum; TrI, protrochanter; TrII, mesotrochanter.

Figures 28–37. Vatellini species, morphology. 28–30, Derovatellus lentus, speleum; 28, apical half of speleum, dorsal aspect with gland reservoirs removed; 29, dorsal aspect, dorsal surface of sternum VI, and gland reservoirs present; 30, left lateral aspect. 31–37, Derovatellus species, spelea and dorsal surfaces of sterna V–VI; 31, D. fasciatus; 32, D. decellei; 33, D. wewalkai; 34, D. dagombae; 35, D. nyanzae; 36, D. lugubris; 37, D. bisignatus.

Figures 57–61. Derovatellus bruchi. 57–59, male genitalia; 57, median lobe, right lateral aspect; 58, median lobe, ventral aspect; 59, right lateral lobe, lateral aspect; 60–61, female genitalia; 60, ventral aspect; 61, spermatheca and associated structures, dorsal aspect. BC, bursa copulatrix; FC, fertilization sac sclerite; FD, fertilization duct; GC, gonocoxa; GS, gonocoxosternite; ID, intermediate duct; RA, rami; RE, receptacle; SD, spermathecal duct; SP, spermatheca; TP, truncate spermathecal process.

Figures 182–188. Vatellus haagi. 182–185, male genitalia; 182, median lobe, right lateral aspect; 183, median lobe, ventral aspect; 184, right lateral lobe, lateral aspect; 185, apex of median lobe, ventral aspect; 186–188, female genitalia; 186, ventral aspect; 187, bursa copulatrix, left lateral aspect; 188, spermatheca and associated structures, dorsal aspect; BC, bursa copulatrix; FC, fertilization sac sclerite; FD, fertilization duct; GC, gonocoxa; GS, gonocoxosternite; ID, intermediate duct; RA, rami; RE, receptacle; SD, spermathecal duct; SP, spermatheca; TP, truncate spermathecal process.

Figures 51–56. Derovatellus bruchi. 51, dorsal habitus; 52, medial portion of metacoxae; 53, left metatrochanter and metafemur, anterior aspect; 54–55, tarsomeres, dorsal aspect; 54, male; 55, female, A, protarsus; B, mesotarsus; 56, speleum and abdominal sterna V, VI, dorsal aspect.

Figures 68–72. Derovatellus spangleri. 68, dorsal habitus; 69, speleum and abdominal sterna V, VI, dorsal aspect 70–72, male genitalia; 70, median lobe, right lateral aspect; 71, median lobe, ventral aspect; 72, right lateral lobe, lateral aspect.

Figures 96–101. Derovatellus lentus. 96, dorsal habitus; 97, medial portion of metacoxae; 98, left metatrochanter and metafemur, anterior aspect; 99–100, tarsomeres, dorsal aspect; 99, male; 100, female, A, protarsus; B, mesotarsus; 101, speleum and abdominal sterna V, VI, dorsal aspect.

Figures 102–105. Derovatellus lentus. 102–104, male genitalia; 102, median lobe, ventral aspect; 103, median lobe, right lateral aspect; 104, right lateral lobe, lateral aspect; 105, female genitalia, ventral aspect.

Figures 174–181. Vatellus haagi. 174, dorsal habitus; 175, elytral sculpture in area indicated on habitus by dotted square; 176, medial portion of metacoxae; 177, metatrochanter and metafemur, anterior aspect; 178–179, tarsomeres, dorsal aspect; 178, male; 179, female, A, protarsus; B, mesotarsus; 180, sternum VI, ventral aspect; 181, speleum abdominal sterna V, VI, dorsal aspect.

Figures 267–273. Vatellus grandis. 267–268, metatrochanter and metafemur, anterior aspect; 267, in flexion; 268, in extension; 269–271, male genitalia; 269, median lobe, right lateral aspect; 270, median lobe, ventral aspect; 271, right lateral lobe, lateral aspect; 272–273, female genitalia; 272, ventral aspect; 273, spermatheca and associated structures, dorsal aspect.

Figures 216–223. Vatellus tarsatus. 216, dorsal habitus; 217, elytral sculpture in area indicated on habitus by dotted square; 218, medial portion of metacoxae; 219, metatrochanter and metafemur, anterior aspect; 220–221, tarsomeres, dorsal aspect; 220, male; 221, female, A, protarsus; B, mesotarsus; 222, sternum VI, ventral aspect; 223, speleum abdominal sterna V, VI, dorsal aspect.