Bitcoind doesn't support BIP32 keys yet. The reason bip32 keys look unfamiliar, is they serialize other stuff besides the private key. Chain code, address number, depth (how many parents to the master key), and the fingerprint of the parent..
So, from the private key above, using this library, you need to 'BIP32::import()' the extended key in order to access the 'key' parameter. This is the hex private key, so you need to call BitcoinLib::private_key_to_WIF($imported_bip32key['key'], '6f', TRUE) - 6f for testnet; TRUE to return a WIF for a compressed pubkey address.
You can import WIF keys into bitcoind then!
<?php
$bitcoinprivkey = "tprv8dbLDXsfGU1PG9aHtCZKGybntES6SdhEwLWpsKCrsCieLX5x7nGGvwwaqTnyW7R8VyockuvAoFhseNM6NcUDgWoqQdHWAqt3ynRG5GwAYBZ";
$label= 'test import key';
$decoded_key = BIP32::import($bitcoinprivkey);
$private_key_hex = $decoded_key['key']; // hexadecimal
$wif = BitcoinLib::private_key_to_WIF(); // base58 wallet import format
?>
<tr><td>Get importprivkey </td><td><?php echo $bc->importprivkey ($bitcoinprivkey, $label); ?></td></tr>
If you do:
print_r(BIP32::import('tprv8baY42qkWkxUTXPRrkfNx1iEg3GxVJBeGRrbFWorwjao6a4KFtycUcY2Rjp5tXvGeQwvXH3s7KA
HCKkueb8bjPnHFGZEfc3eYc6v437192G'));
You'll see all the data which is compacted into BIP32 keys, making them longer, but assisting with the deterministic algorithm used to generate them.